United Airlines

Boeing 737 MAX 8

On October 16, 2025, at 0643 mountain daylight time (MDT), United Airlines (UAL) flight 1093, a Boeing 737-8, N17327, was involved in a midair collision with an object while in cruise flight near Moab, Utah. Although the captain sustained minor injuries, none of the other 111 occupants onboard the airplane were injured. The scheduled domestic passenger flight was operating under the provisions of Title 14 Code of Federal Regulations (CFR) Part 121 from Denver International Airport (DEN), Denver, Colorado to Los Angeles International Airport (LAX), Los Angeles, California. Following the incident, the flight diverted to Salt Lake City International Airport (SLC), Salt Lake City, Utah. According to the captain, while established in cruise flight at flight level 360 (36,000 ft pressure altitude), he noticed an object distant on the horizon. Before he could mention the object to the first officer (FO), there was a significant impact to the FO’s forward windshield along with a loud bang. The impact resulted in both pilots being showered with pieces of glass. The captain sustained multiple superficial lacerations to his right arm; the FO was uninjured. Following the event, the flight crew coordinated with air traffic control and initiated a descent. The cabin pressurization remained stable, with no fluctuations throughout the flight. The captain transferred control of the airplane to the FO while he conducted associated checklists and communicated with dispatch and the flight attendants (FAs). During this time, the FO’s window overheat light illuminated and the crew addressed it per the applicable checklist. After coordination with dispatch, the crew selected SLC as the most suitable diversion airport. The captain notified the passengers of the diversion and FAs were briefed to prepare the cabin for landing. The captain then initiated self-care to clean, sterilize, and bandage his wounds on his arm. The captain subsequently resumed pilot flying duties for descent and landing. The flight was vectored for an ILS approach to runway 16L at SLC. The approach and landing were uneventful. The aircraft taxied to the gate under its own power, escorted by airport rescue and firefighting vehicles. Upon arrival at the gate, emergency medical personnel provided the captain with first aid. There were no other reported injuries. After the event was reported, data was requested for the position of weather balloons, any other aircraft, and for any known reentry objects that were large enough to have signification portions survive that might have been in the area of the collision. WindBorne Systems Inc. reported that they lost contact with one of their global sounding balloons (GSBs) that was in the vicinity of the airplane at the time of the accident. The GSB was launched from Spokane, Washington at 1129 MDT on October 15, 2025. The balloon traveled south from Washington, down through Oregon and Nevada before turning northeast, and was crossing though Utah at the time of the accident. There was a Notice to Airman, GEG 10/068, issued at 816 MDT for the balloon launch operations at Spokane that expired at 1700 MDT the same day, October 15, 2025. The GSB stopped communicating with the ground on October 16, 2025, between 0636:16 and 0643:36 MDT. The last communication from the GSB reported that the pressure altitude was 35,936 ft (which had been oscillating between 35,800 and 36,200 ft over the preceding hour). The GSB self-reported location was latitude 38.53142N and longitude 109.41600W and the wind was 73 knots from the southwest. According to WindBorne, the GSB is a lightweight, long duration high-altitude weather balloon platform operated under the provisions of Title 14 CFR Part 101.1. It is an unmanned free balloon. The GSB system consists of a balloon envelope filled with lift gas, an avionics package for flight control, communications, and sensing, and a ballast system for altitude control. According to Windborne the GSBs are designed with the intent to minimize harm in the event of an impact during flight or landing. No large metal or high-stiffness structural elements are employed. The balloon envelope and the ballast container are a thin, low tensile strength, plastic film. The silica ballast is relatively low density and low grain-size. The windshield installed in N17327 was manufactured by PPG Aerospace and was designed to withstand the flight and pressurization loads encountered during flight while providing visibility for the pilots. From outboard to inboard, the windshield consists of a thermally tempered glass pane, a conductive heating film for deice capabilities, a urethane interlayer, a vinyl interlayer, a urethane interlayer, and a thermally tempered glass pane. The windshield is surrounded by a stainless-steel z-bar encased in a moisture seal to attach it to the fuselage. A coating is applied to the outer surface of the outboard pane to improve the ability to shed water in rainy conditions. Windshields are certified to withstand the impact of a four-pound bird without penetration, to be capable of withstanding the maximum cabin pressurization loads with the failure of a single pane, and the internal pane must be non-splintering. The inboard pane of glass is considered a structural pane, the vinyl interlayer is considered a structural fail-safe pane, and the outboard pane of glass is considered a non-structural pane for this design. The damaged right windshield from the accident airplane, P/N 29-5612-9-9008, S/N 23089H0823, was manufactured on March 30, 2023. The damaged windshield was removed from the airplane and sent to the NTSB Materials Lab in Washington, DC for examination. In addition, the flight data and the cockpit voice recorder were sent to the NTSB Vehicle Recorder Laboratory in Washington, DC. A preliminary review of the data from the cockpit voice and flight data recorders revealed that at the time of the collision, the airplane’s track was to the southwest at 233° magnetic (nearly the reciprocal of the balloon track), at a pressure altitude of 36,002 ft, and a groundspeed of 395 knots. This investigation is ongoing.

Boeing 757-200

The Boeing 757 departed Newark Airport at 0847LT on a regular schedule service to San Francisco, carrying 37 passengers and a crew of seven. Few minutes later, the aircraft was hijacked by terrorists who modified the flight path and apparently attempted to fly over Washington DC. At 1030LT, the aircraft crashed in an open field located about 4 km north of Shanksville. The aircraft disintegrated on impact and all 45 occupants were killed. The terrorist attacks of September 11, 2001 are under the jurisdiction of the Federal Bureau of Investigation. The Safety Board provided requested technical assistance to the FBI, and this material generated by the NTSB is under the control of the FBI. The Safety Board does not plan to issue a report or open a public docket.

Boeing 767-200

The Boeing 767 departed Boston-Logan Airport at 0814LT on a regular schedule service to Los Angeles, carrying 56 passengers and a crew of nine. Few minutes later, the aircraft was hijacked by terrorists who modified the flight path and flew direct over New York. At 0903LT, the aircraft struck the South Tower of the World Trade Center, between 78th and 84th floor. The aircraft disintegrated on impact and all 65 occupants were killed. The tower later collapsed. The terrorist attacks of September 11, 2001 are under the jurisdiction of the Federal Bureau of Investigation. The Safety Board provided requested technical assistance to the FBI, and this material generated by the NTSB is under the control of the FBI. The Safety Board does not plan to issue a report or open a public docket.

Boeing 737-200

On March 3, 1991, a United Airlines Boeing 737, registration number N999UA, operating as flight 585, was on a scheduled passenger flight from Denver, Colorado, to Colorado Springs, Colorado. Visual meteorological conditions prevailed at the time, and the flight was on an instrument flight rules flight plan. Numerous witnesses reported that shortly after completing its turn onto the final approach course to runway 35 at Colorado Springs Municipal Airport, about 0944 mountain standard time, the airplane rolled steadily to the right and pitched nose down until it reached a nearly vertical attitude before hitting the ground in an area known as Widefield Park. The airplane was destroyed, and the 2 flight crewmembers, 3 flight attendants, and 20 passengers aboard were fatally injured.

Douglas DC-10

United Flight 232 departed Denver-Stapleton International Airport, Colorado, USA at 14:09 CDT for a domestic flight to Chicago-O'Hare, Illinois and Philadelphia, Pennsylvania. There were 285 passengers and 11 crew members on board. The takeoff and the en route climb to the planned cruising altitude of FL370 were uneventful. The first officer was the flying pilot. About 1 hour and 7 minutes after takeoff, at 15:16, the flightcrew heard a loud bang or an explosion, followed by vibration and a shuddering of the airframe. After checking the engine instruments, the flightcrew determined that the No. 2 aft (tail-mounted) engine had failed. The captain called for the engine shutdown checklist. While performing the engine shutdown checklist, the flight engineer observed that the airplane's normal systems hydraulic pressure and quantity gauges indicated zero. The first officer advised that he could not control the airplane as it entered a right descending turn. The captain took control of the airplane and confirmed that it did not respond to flight control inputs. The captain reduced thrust on the No. 1 engine, and the airplane began to roll to a wings-level attitude. The flightcrew deployed the air driven generator (ADG), which powers the No. 1 auxiliary hydraulic pump, and the hydraulic pump was selected "on." This action did not restore hydraulic power. At 15:20, the flightcrew radioed the Minneapolis Air Route Traffic Control Center (ARTCC) and requested emergency assistance and vectors to the nearest airport. Initially, Des Moines International Airport was suggested by ARTCC. At 15:22, the air traffic controller informed the flightcrew that they were proceeding in the direction of Sioux City; the controller asked the flightcrew if they would prefer to go to Sioux City. The flightcrew responded, "affirmative." They were then given vectors to the Sioux Gateway Airport (SUX) at Sioux City, Iowa. A UAL DC-10 training check airman, who was off duty and seated in a first class passenger seat, volunteered his assistance and was invited to the cockpit at about 15:29. At the request of the captain, the check airman entered the passenger cabin and performed a visual inspection of the airplane's wings. Upon his return, he reported that the inboard ailerons were slightly up, not damaged, and that the spoilers were locked down. There was no movement of the primary flight control surfaces. The captain then directed the check airman to take control of the throttles to free the captain and first officer to manipulate the flight controls. The check airman attempted to use engine power to control pitch and roll. He said that the airplane had a continuous tendency to turn right, making it difficult to maintain a stable pitch attitude. He also advised that the No. 1 and No. 3 engine thrust levers could not be used symmetrically, so he used two hands to manipulate the two throttles. About 15:42, the flight engineer was sent to the passenger cabin to inspect the empennage visually. Upon his return, he reported that he observed damage to the right and left horizontal stabilizers. Fuel was jettisoned to the level of the automatic system cutoff, leaving 33,500 pounds. About 11 minutes before landing, the landing gear was extended by means of the alternate gear extension procedure. The flightcrew said that they made visual contact with the airport about 9 miles out. ATC had intended for flight 232 to attempt to land on runway 31, which was 8,999 feet long. However, ATC advised that the airplane was on approach to runway 22, which was closed, and that the length of this runway was 6,600 feet. Given the airplane's position and the difficulty in making left turns, the captain elected to continue the approach to runway 22 rather than to attempt maneuvering to runway 31. The check airman said that he believed the airplane was lined up and on a normal glidepath to the field. The flaps and slats remained retracted. During the final approach, the captain recalled getting a high sink rate alarm from the ground proximity warning system (GPWS). In the last 20 seconds before touchdown, the airspeed averaged 215 KIAS, and the sink rate was 1,620 feet per minute. Smooth oscillations in pitch and roll continued until just before touchdown when the right wing dropped rapidly. The captain stated that about 100 feet above the ground the nose of the airplane began to pitch downward. He also felt the right wing drop down about the same time. Both the captain and the first officer called for reduced power on short final approach. The check airman said that based on experience with no flap/no slat approaches he knew that power would have to be used to control the airplane's descent. He used the first officer's airspeed indicator and visual cues to determine the flightpath and the need for power changes. He thought that the airplane was fairly well aligned with the runway during the latter stages of the approach and that they would reach the runway. Soon thereafter, he observed that the airplane was positioned to the left of the desired landing area and descending at a high rate. He also observed that the right wing began to drop. He continued to manipulate the No. 1 and No. 3 engine throttles until the airplane contacted the ground. He said that no steady application of power was used on the approach and that the power was constantly changing. He believed that he added power just before contacting the ground. The airplane touched down on the threshold slightly to the left of the centerline on runway 22 at 16:00. First ground contact was made by the right wing tip followed by the right main landing gear. The airplane skidded to the right of the runway and rolled to an inverted position. Witnesses observed the airplane ignite and cartwheel, coming to rest after crossing runway 17/35. Firefighting and rescue operations began immediately, but the airplane was destroyed by impact and fire. The accident resulted in 111 fatal, 47 serious, and 125 minor injuries. The remaining 13 occupants were not injured.

Douglas DC-8

United Flight 2885 departed Cleveland at 01:15 for a cargo flight to Los Angeles via Detroit. The DC-8 arrived at Detroit at 01:52. Cargo for Detroit was unloaded, the airplane was refueled, and cargo for Los Angeles was loaded. The engines were started, and then the crew called for taxi instructions at 02:45:58. During the taxi, the flightcrew accomplished the before takeoff checklist. The second officer called "trim" and the first officer responded "set". The flightcrew however, inadvertently overlooked setting the stabilizer trim for takeoff, and the setting of 7.5 units ANU was the previous landing trim setting. At 02:49:16, the captain, the first officer, and the second officer discussed the idea of the first officer switching seats with the second officer. They then switched seats about 02:49:40. United 2885 called for clearance onto runway 21R at 02:49:58 and was cleared for takeoff at 02:50:03. The throttles were advanced for takeoff at 02:51:05 and power stabilized 7 seconds later. Speed callouts "eighty knots" and "Vee One" were called by the captain and the airplane broke ground about 02:51:41. The airplane continued to climb with wings level to about 1,000 feet. The airplane then rolled to the right in a gradual right turn until it was in a wings vertical position (right wing down, left wing up) and crashed into a freshly plowed farm field.

Douglas DC-8

United Airlines Flight 173, departed New York-JFK on a scheduled flight to Portland International Airport (PDX), with an en route stop at Denver (DEN). The DC-8-61 took off from Denver about 14:47. The planned time en route was 2 hrs 26 min. The planned arrival time at Portland was 17:13. There was 46,700 lb of fuel on board the aircraft when it departed the gate at Denver. This fuel included the Federal Aviation Regulation requirement for fuel to destination plus 45 min and the company contingency fuel of about 20 min. At 17:05, Flight 173 called Portland Approach and advised that its altitude was 10,000 ft and its airspeed was being reduced. Portland responded and told the flight to maintain its heading for a visual approach to runway 28. Flight 173 acknowledged the approach instructions and stated, "...we have the field in sight." At 17:07, Portland Approach instructed the flight to descend and maintain 8,000 ft. Flight 173 acknowledged the instructions and advised that it was "leaving ten." At 17:09, Flight 173 received and acknowledged a clearance to continue its descent to 6,000 ft. When the DC-8 was descending through about 8,000 ft, the first officer, who was flying the aircraft, requested the wing flaps be extended to 15 degrees, then asked that the landing gear be lowered. As the landing gear extended, an unusual sound was heard and the aircraft yawed. At 17:12, Portland Approach requested, "United one seven three heavy, contact the tower, one one eight point seven." The flight responded, "negative, we'll stay with you. We'll stay at five. We'll maintain about a hundred and seventy knots. We got a gear problem. We'll let you know." Portland Approach replied, "United one seventy-three heavy roger, maintain five thousand. Turn left heading two zero zero." The flight acknowledged the instructions. At 17:14, Portland Approach advised, "United one seventy three heavy, turn left heading, one zero zero and I'll just orbit you out there 'til you get your problem." Flight 173 acknowledged the instructions. For the next 23 min, while Portland Approach was vectoring the aircraft in a holding pattern south and east of the airport, the flight crew discussed and accomplished all of the emergency and precautionary actions available to them to assure themselves that all landing gear was locked in the full down position. The second officer checked the visual indicators on top of both wings, which extend above the wing surface when the landing gear is down-and-locked. About 17:38, Flight 173 contacted the United Airlines Systems Line Maintenance Control Center in San Francisco. The captain explained to company dispatch and maintenance personnel the landing gear problem and what the flight crew had done to assure that the landing gear was fully extended. He said they were planning to land in about twenty minutes. About 17:44, the captain and the first flight attendant discussed passenger preparation, crash landing procedures, and evacuation procedures. At 17:46, the first officer asked the flight engineer, "How much fuel we got...?" The flight engineer responded, "Five thousand." About 17:50, the captain asked the flight engineer to "Give us a current card on weight. Figure about another fifteen minutes." The first officer responded, "Fifteen minutes?" To which the captain replied, "Yeah, give us three or four thousand pounds on top of zero fuel weight." The flight engineer then said, "Not enough. Fifteen minutes is gonna really run us low on fuel here." Some calculations were made and at 17:52 the flight engineer talked to Portland and discussed the aircraft's fuel state, the number of persons on board the aircraft, and the emergency landing precautions at the airport. A fuel check at 17:57 learned that there were 1,000 lb in each tank, totalling 4,000 lb of fuel. From 17:57 until 18:00, the captain and the first officer engaged in a conversation which included discussions of giving the flight attendants ample time to prepare for the emergency, cockpit procedures in the event of an evacuation after landing, whether the brakes would have antiskid protection after landing, and the procedures the captain would be using during the approach and landing. At 18:01, the flight engineer reported that the cabin would be ready in "another two or three minutes." At 18:02, the flight engineer advised, "We got about three on the fuel and that's it." The aircraft was then about 5 nmi south of the airport on a southwest heading. Portland Approach then asked Flight 173 for a status report. The first officer replied, "Yeah, we have indication our gear is abnormal. It'll be our intention, in about five minutes, to land on two eight left. We would like the equipment standing by. Our indications are the gear is down and locked. We've got our people prepared for an evacuation in the event that should become necessary." At 18:03 Portland Approach asked that Flight 173 advise them when the approach would begin. The captain responded, "...They've about finished in the cabin. I'd guess about another three, four, five minutes." At this time the aircraft was about 8 nmi south of the airport on a southwesterly heading. At 18:06, the first flight attendant entered the cockpit and reported that they were ready in the passenger cabin. At this time the aircraft was about 17 nmi south of the airport on a southwesterly heading. The captain then said, "Okay. We're going to go in now. We should be landing in about five minutes." Almost simultaneous with this comment, the first officer said, "I think you just lost number four ..." followed immediately by advice to the flight engineer, "... better get some crossfeeds open there or something." At 18:06:46, the first officer told the captain, "We're going to lose an engine..." At 18:06:49, the first officer again stated, "We're losing an engine." Again the captain asked, "Why?" The first officer responded, "Fuel." The captain replied, "Why?" Between 18:06:52 and 18:07:06, the CVR revealed conflicting and confusing conversation between flight crewmembers as to the aircraft's fuel state. At 18:07:06, the first officer said, "It's flamed out." At 18:07:12, the captain called Portland Approach and requested, "...would like clearance for an approach into two eight left, now." The aircraft was about 19 nmi south southwest of the airport and turning left. This was the first request for an approach clearance from Flight 173 since the landing gear problem began. Portland Approach immediately gave the flight vectors for a visual approach to runway 28L. The flight turned toward the vector heading of 010 degrees. At 18:09:21, the captain advised Portland Approach, "United, seven three is going to turn toward the airport and come on in." After confirming Flight 173's intentions, Portland Approach cleared the flight for the visual approach to runway 28L. At 18:10:17, the captain requested that the flight engineer "reset that circuit breaker momentarily. See if we get gear lights." The flight engineer complied with the request. At 18:10:47, the captain requested the flight's distance from the airport. Portland approach responded, "I'd call it eighteen flying miles." At 18:12:42, the captain made another request for distance. Portland Approach responded, "Twelve flying miles." The flight was then cleared to contact Portland tower. At 18:13:21, the flight engineer stated, "We've lost two engines, guys." At 18:13:25, he stated, "We just lost two engines - one and two." At 1813:38, the captain said, They're all going. We can't make Troutdale." The first officer said, "We can't make anything." At 18:13:46, the captain told the first officer, "Okay. Declare a mayday." At 18:13:50, the first officer called Portland International Airport tower and declared, "Portland tower, United one seventy three heavy, Mayday. We're--the engines are flaming out. We're going down. We're not going to be able to make the airport." This was the last radio transmission from Flight 173. About 18:15, the aircraft crashed into a wooded section of a populated area of suburban Portland about 6 nmi east southeast of the airport. There was no fire. The wreckage path was about 1,554 ft long and about 130 ft wide. Two crew members and eight passengers were killed, 34 other occupants were injured.

Douglas DC-8

About 0138:28 m.s.t. on December 18, 1977, a United Airlines, Inc., DC-8F-54 cargo aircraft, operating as Flight 2860, crashed into a mountain in the Wasatch Range near Kaysville, Utah. The three flightcrew members, the only persons aboard the aircraft, were killed, and the aircraft was destroyed. Flight 2860 encountered electrical system problems during its descent and approach to the Salt Lake City Airport. The flight requested a holding clearance which was given by the approach controller and accepted by the flight crew. The flight then requested and received clearance to leave the approach control frequency for a "little minute" to communicate with company maintenance. Flight 2860 was absent from the Approach control frequency for 7 1/2 minutes. During that time, the flight entered an area near hazardous terrain. The approach controller recognized Flight 2860's predicament but was unable to contact the flight. When flight 2860 returned to approach control frequency, the controller told the flight that it was too close to terrain on its right and to make a left turn. After the controller repeated the instructions, the flight began a left turn and about 15 seconds later the controller told the flight to climb immediately to 8,000 feet. Eleven seconds later, the flight reported that it was climbing from 6,000 feet to 8,000 feet. The flight crashed into a 7,665-foot mountain near the 7,200-foot level. The aircraft was destroyed and all three crew members were killed.

Boeing 737-200

Flight UA553 departed Washington-National Airport at 1250LT for Omaha with an intermediate stop at Chicago-Midway Airport. Chicago ARTCC cleared the crew to descend to 4000 feet and the flight was given vectors for a Midway Airport runway 31L localizer course. At 14:19 the flight was transferred to Chicago Approach Control which later requested UA553 to slow down to 180 knots and later down to 160 knots. After issuing a descent clearance down to 2000 feet at 14:23 the controller requested the flight to slow down to approach speed because of separation between UA553 and a preceding Aero Commander. At 14:24 the Aero Commander passed the Outer Marker and was cleared to land on runway 31L. Two minutes later UA553 passed the Outer Marker inbound. Then, at 14:27:04 the air traffic controller decided to issue a missed approach clearance: "United 553 execute a missed approach make a left turn to a heading of 180 climb to 2000". At the same time, having just reached 1000 feet, the stick shaker suddenly activated. Full power was applied and the gear was retracted in an attempt to execute a missed approach. The Boeing continued to descend however, attaining a high nose up attitude (of at least 30deg, according to some survivors). The aircraft then clipped a tree and impacted trees, houses, utility pole cables and garages before coming to rest. Post crash fire destroyed part of the fuselage.

Boeing 737-200

At 18:50 Boeing 737 "City of Bristol" taxied to runway 09 for departure. At 19:05 the first officer, who was pilot flying, initiated the takeoff roll. Shortly after rotation, at a speed above V2, a loud bang was heard and the aircraft veered to the right. The captain moved both throttles forward but there seemed to be no response. The captain then made the instantaneous decision to set the aircraft back on the runway. The aircraft touched down 1075 feet short of the runway end. The 737 continued of the end of the runway and across the blast pad. It crossed a field, passed through a 6-foot high aluminum chain link fence into an area covered with high grass, weeds and brush. The aircraft came to rest 1634 feet past the end of the runway.

Boeing 727-100

Boeing 727-22C N7434U operated Flight 266 from Los Angeles to Denver, CO and Milwaukee, WI. The aircraft had been operating since January 15, 1969, with the No. 3 generator inoperative. This was allowed because according to the Minimum Equipment List, the aircraft is airworthy with only two generators operable provided certain procedures are followed and electrical loads are monitored during flight. Flight 266 was scheduled to depart the gate at 17:55, but was delayed until 18:07 because of the inclement weather and loading problems. The flight commenced its takeoff roll on runway 24 at approximately 18:17. At 18:18:30 the sound of an engine fire warning bell was heard in the cockpit. The crew reported a no. 1 engine fire warning and stated that they wanted to return to the airport. Shortly after shutdown of the No. 1 engine, electrical power from the remaining generator (No. 2) was lost. Following loss of all generator power, the standby electrical system either was not activated or failed to function. Electrical power at a voltage level of approximately 50 volts was restored approximately a minute and a half after loss of the No. 2 generator. The duration of this power restoration was just 9 to 15 seconds. The Boeing descended and struck the sea 11.3 miles west of the airport. The ocean depth at this point is approximately 950 feet.

Boeing 727-100

The takeoff warning horn sounded shortly after commencing takeoff from runway 09R. The takeoff was continued as the crew tried to figure out what caused the warning. The horn ceased prior to reaching rotate speed. The stick shaker came on and thrust was added, but the aircraft failed to climb and the captain elected to discontinue the takeoff. The 727 settled back to the macadam shoulder off the right side of the runway and struck a ditch, coming to rest 1,100 feet beyond the runway end and 300 feet right of the extended centreline. The aircraft was destroyed by a post crash fire and all three crew members were injured. The flaps had been set at 2° instead of takeoff range of 5°-25°.

Vickers Viscount

After touchdown at Akron-Canton Airport, the four engine airplane encountered difficulties to stop within the remaining distance. It overran, lost its undercarriage and went down an 23 feet embankment before coming to rest 400 feet further. A passenger was seriously injured while all other occupants escaped uninjured. The aircraft was written off.

Vickers Viscount

After touchdown at Raleigh-Durham Airport by night, the nosewheel collapsed. The airplane slid on the runway for several yards until it came to rest. All 43 occupants escaped uninjured while the aircraft was later considered as damaged beyond repair.

Vickers Viscount

Following a normal touchdown at Norfolk Municipal Airport, the crew started the braking procedure when the airplane collided with a snow plow. A wing was torn off and the snowplow was dragged over several meters. There were no injuries but the aircraft was damaged beyond repair.

Douglas DC-7

The crew was completing a local training flight at Denver-Stapleton Airport. On touchdown, one of the nose wheel tire burst. The landing gear collapsed and the airplane slid on its nose for several yards before coming to rest. All four crew members were uninjured while the aircraft christened 'Mainliner Capt Ralph Jonston was considered as damaged beyond repair.

Boeing 727-100

Flight 227 took off from New York-LaGuardia (LGA) for a flight to San Francisco (SFO) via Cleveland (CLE), Chicago (MDW), Denver (DEN) and Salt Lake City (SLC). The aircraft took off from Denver at 16:54 and climbed to its assigned cruising altitude of FL310. At 17:38 flight 227 began its descent for Salt Lake City. The flight proceeded in accordance with radar vectors. After a radar handoff to Salt Lake City Approach Control new clearance altitudes were given. At 17:47 the approach controller advised, "United seventy twenty seven ... five miles south of Riverton Fan Marker coming on localizer course cleared for ILS runway three four left approach." The pilot replied "Okay we're slowed to two fifty (Knots) and we're at ten (10,000 feet) we have the runway in sight now, we'll cancel and standby with you for traffic." Control of the flight was transferred to the tower and at 17:49:40 landing clearance was issued. The aircraft crossed the outer marker over 2,000 fee & above the ILS glide slope. The rate of descent during the final approach exceeded 2,000 ft/min, approximately three times the United Air Lines recommended rate of descent for landing approaches. The first officer attempted to apply power but the captain stopped him. Power was then applied too late to arrest the rate of descent. The airplane touched down 335 feet short of the threshold of runway 34L. The right and left main landing gear began to separate and the airplane slid onto the runway. Severe upward and rearward impact forces from the right main Landing gear assembly produced a large impact hole and ruptured fuel lines and the no. 3 generator leads between fuselage station 1030 and 1130 on the right side. The fuel was ignited by sparks from the fuselage scraping on the runway and/or the severed generator leads. 13 passengers were uninjured while 35 people were wounded. 43 other occupants were killed.

Douglas DC-6

During the takeoff roll at Huntsville Airport, when V1 speed was reached, the pilot-in-command started the rotation when the nose gear retracted. The airplane sank on its nose, slid for several yards, overran and came to rest 300 feet further. All 16 occupants were evacuated safely while the aircraft was damaged beyond repair.

Boeing 727-100

A United Air Lines, Inc., Boeing 727-22, N7036U, Flight 389 (UAL 389) was a regularly scheduled domestic passenger/cargo flight from LaGuardia Airport, New York to O'Hare International Airport, Chicago, Illinois. The aircraft had arrived at LaGuardia, on the date of the accident, following a trip from Los Angeles, California, with stops at Sacramento, California, Reno, Nevada, Denver, Colorado, and Chicago, Illinois. The flight crew of UAL 389 reported for duty at LaGuardia Airport one hour before scheduled departure where they prepared for the flight to Chicago. The stewardesses arrived with the aircraft from Chicago. Persons known to have been in contact with the crew prior to their departure from New York noticed nothing unusual about their behavior or appearance. UAL 389 departed LaGuardia at 1952 on an Instrument Flight Rules (IFR) flight plan at FL 350 and estimated their arrival time at O'Hare to be 2127. The crew reported at FL 350 at 2011.35. At 2102 UAL 389 came under control of the Chicago Air Route Traffic Control Center (ARTCC) reporting its altitude as FL 350 and was cleared to the O'Hare Airport via Pullman VORTAC direct to the Northbrook VORTAC, direct O'Hare and to maintain FL 350. This clearance was acknowledged correctly and the crew was advised that radar contact had been established. At 2103 the ARTCC controller cleared UAL 389 to descend to FL 240 and to "start descent now through 31" (FL 310). UAL 389 replied "...down to 240, leaving three five." At 2106 UAL 389 was cleared to continue its descent to 14,000 feet and given an altimeter setting of 29.90 inches for O'Hare. This message was acknowledged immediately and in reply to the controller's inquiry the crew reported they were leaving FL 280 "now." At 2109 the flight was instructed to change frequencies and within the same minute reported out of FL 260 descending to fourteen thousand. This was the last altitude information received from the crew. At 2111 the flight was cleared to descend to 6,000 feet and the clearance was immediately acknowledged correctly. At 2118:35 control of the flight was passed to Chicago Approach Control (ORD). The radar target of UAL 389 was in the vicinity of the Sturgeon Intersection (intersection of the 011 radial of Chicago Heights and 076 radial of Northbrook VORTAC, 28 miles east of Northbrook VORTAC). At 2118:38 the target was observed approximately 2 miles east of the intersection. At 2119:36 the crew contacted ORD and was advised that radar contact had been established. At this time the aircraft target was 2-3 miles west of Sturgeon. UAL 389 was cleared to maintain 6,000 feet and to depart the Northbrook VORTAC on a heading of 240 degrees. The flight was advised that instrument landing system approaches were in progress on runway 14R at O'Hare and that the current O'Hare altimeter setting was 29.93. The pilot read back the altimeter setting incorrectly, the controller corrected him, and the pilot repeated it correctly. This was the last communication received from the flight and ended at 2120:03. The airplane crashed into Lake Michigan and exploded upon impact. All 30 occupants were killed.

Vickers Viscount

A United Air Lines, Inc., Vickers Viscount 745D, N7405, Flight 823, crashed 2-1/4 rules northeast of Parrottsville Tennessee, at 1815 e.s.t., July 9, 1964. Thirty-four passengers and the four crew members died in the crash. One passenger died of injuries following a free fall from the aircraft before the crash. The aircraft was destroyed by fire and impact damage. Flight 823 was a regularly scheduled operation from Philadelphia, Pennsylvania, to Huntsville, Alabama, with en route stops at Washington, D. C., and Knoxville, Tennessee. The flight operated without any reported discrepancies or difficulties until approximately 1810 e.s.t., when it was observed flying at low altitude trailing smoke. The flight continued in a southwesterly direction and at a point approximately 1.6 nautical rules before the impact site, a passenger was seen falling from the aircraft, and a short time later a cabin window was seen falling. The aircraft was then observed going into a nose-high attitude, the left wing and the nose went down, and the aircraft dived into the ground, exploded, and burned.

Vickers Viscount

United Air Lines Flight 297, a Vickers-Armstrong Viscount Model 745D, N7430, crashed in a wooded area six miles west-southwest of Ellicott City, Maryland, at approximately 1224 e.s.t., on November 23, 1962. All thirteen Passengers and a crew of four were fatally injured. Flight 297 was en route from Newark, New Jersey to Washington, D. C. The flight was operating at an assigned altitude of' 6,000 feet when it apparently penetrated a flock of Whistling Swans. At least two of these a were struck by the aircraft. One swan collided with the right horizontal stabilizer inflicting superficial damage only. The other bird punctured the left horizontal stabilizer, traveled through the structure, and dented the elevator as it egresses. The weakened structure failed in this area. rendered the aircraft uncontrollable, and resulted in, the aircraft striking the ground in a nose-low inverted attitude.

Douglas DC-8

On July 11, 1961, at 1136 M.S.T., a United Air Lines DC-8 crashed during its landing roll at Stapleton Airfield, Denver, Colorado. None of the 122 occupants was severely injured as an immediate result of the impact; however, there were 16 passenger fatalities as a result of carbon monoxide poisoning when the aircraft burned. One other passenger, an elderly woman, broke both ankles during evacuation of the airplane and later succumbed to shock. In addition, the driver of a panel truck, which the aircraft struck after leaving the runway, also suffered fatal injuries. After experiencing hydraulic difficulties following takeoff from Omaha, Nebraska, the crew of N8040U continued the flight to Denver, using procedures set forth in the flight manual for abnormal hydraulic situations. When the flight arrived in the Denver area, preparations were made for landing. The ejectors were extended hydraulically, however, when an attempt was made to extend flaps to 25 degrees the hydraulic pressure dropped to zero. The hydraulic system selector was then placed in the No. 3 position (flap and gear downlock), and the approach was continued. After touchdown, the throttles were placed in the idle reverse thrust position and when power was applied, an uncontrollable deviation from the runway occurred.

Douglas DC-8

On December 16, 1960, at 1033 e.s.t., a collision between Trans World Airlines Model 1049A Constellation, N 6907C, and a United Air Lines DC-8, N 8013U, occurred near Miller Army Air Field, Staten Island, New York. Trans World Airlines Flight 266 originated at Dayton, Ohio. The destination was LaGuardia Airport, New York, with one en route stop at Columbus, Ohio United Air Lines Flight 826 was a non-stop service originating at O'Hare Airport, Chicago, Illinois, with its destination New York International Airport, New York. Both aircraft were operating under Instrument Flight Rules. Following the collision the Constellation fell on Miller Army Field, and the DC-8 continued in a northeasterly direction, crashing into Sterling place near Seventh Avenue in Brooklyn, New York. Both aircraft were totally destroyed. All 128 occupants of both aircraft and 6 persons on the ground in Brooklyn were fatally injured. There was considerable damage to property in the area of the ground impact of the DC-8. TWA Flight 266 departed Port Columbus Airport at 0900, operating routinely under Air Traffic Control into the New York area The New York Air Route Traffic Control Center (ARTCC) subsequently advised that radar contact had been established and cleared the flight to the Linden. Intersection, Control of the flight was subsequently transferred to LaGuardia Approach Control. When the flight was about over the Linden Intersection, LaGuardia Approach Control began vectoring TWA 266 by radar to the final approach course for a landing on runway 4 at LaGuardia. Shortly thereafter TWA 266 was cleared to descend to 5,000 feet, and was twice advised of traffic in the vicinity on a northeasterly heading. Following the transmission of this information the radar targets appeared to merge on the LaGuardia Approach Control radar scope, and communications with TWA 266 were lost.United Air Lines Flight 826 operated routinely between Chicago and the New York area, contacting the New York ARTCC at 1012 Shortly thereafter the New York Center cleared UAL 826 to proceed from the Allentown, Pa., very high frequency omni directional radio range station (VOR) direct to the Robbinsville, New Jersey, VOR, and thence to the Preston Intersection via Victor Airway 123. At approximately 1021, UAL 826 contacted Aeronautical Radio, Inc. (ARINC) to advise their company that the No. 2 receiver accessory unit was inoperative, which would indicate that one of the aircraft's two VHF radio navigational receivers was not functioning. A "fix" is established by the intersection of two radials from two separate radio range stations. With one unit inoperative the cross-bearings necessary can be taken by tuning the remaining receiver from one station to the other. This process consumes considerable time, however, and is not as accurate as the simultaneous display of information on two separate position deviation indicators While UAL 826 advised the company that one unit was inoperative, Air Traffic Control was not advised. At 1025 the New York ARTCC issued a clearance for a new routing which shortened the distance to Preston by approximately 11 miles. As a result, this reduced the amount of time available to the crew to retune the single radio receiver to either the Colt' s Neck, New Jersey, or Solberg, New Jersey, VOR in order to establish the cross-bearing with Victor 123, which would identify the Preston Intersection. In the event the crew would not attempt to retune the single VOR receiver, crossbearings on the Scotland Low Frequency Radiobeacon could be taken with the aircraft direction finding (ADF) equipment. This would be a means of identifying the Preston Intersection but, under the circumstances, would require rapid mental calculation in the interpretation of a display which could be easily misread. Several factors support the conclusion that this occurred. Instructions had been issued to UAL 826 for holding at the Preston Intersection the clearance limit, should holding be necessary. Clearance beyond Preston for an approach to Idlewild Airport would be received from Idlewild Approach Control and the transfer of control of the flight from the New York Center to Idlewild Approach Control would normally take place as the aircraft was approaching Preston. UAL 826 was not receiving radar vectors, but was providing its own navigation. After the flight reported passing through 6,000 feet the New York Center advised that radar service was terminated and instructed the flight to contact Idlewild Approach Control. UAL 826 then called Idlewild Approach Control, stating "United 826 approaching Preston at 5,000." This was the last known transmission from UAL 826. At the time UAL 826 advised it was approaching Preston it had in fact gone on by this clearance limit several seconds before and was several miles past the point at which it should have turned into the holding pattern. This is confirmed by the data obtained from the flight recorder which had been installed in the UAL DC-8, as well as by analysis of the communication tapes At a point approximately 11 miles past the Preston Intersection a collision occurred between TWA 266 and UAL 826. Weather at the altitude of the collision and at the time of the accident was such as to preclude flight by visual means.

Douglas DC-7

United Airlines Flight 736 departed Los Angeles International Airport at 0737 hours Pacific standard time with 42 passengers and 5 crew aboard. It was a scheduled passenger flight to New York, which was proceeding normally in accordance with an IFR flight plan along Victor Airway 16 to Ontario, California, and Victor Airway 8 to Denver. The aircraft was cleared to a cruising altitude of 21 000 ft msl and advised to climb in VFR weather conditions. At 0735 the flight reported to Aeronautical Radio that it was over Ontario at 12 000 ft and was climbing in VFR conditions. Then at 081 1 it reported over Daggett at its cruising altitude of 21 000 ft and estimated that it would reach Las Vegas (omni range station) at 0831, This was the last position report made by the flight. At approximately 0745 hours that morning F-100F, 56-3755, took off from Nellis Air Force Base, Las Vegas, Nevada on an instrument training flight carrying an instructor and a trainee pilot. The flight was in accordance with a VFR local flight plan filed with Nellis Operations and the local traffic control tower. At approximately 0823, 755 called Nellis VFR Control and reported that it was "inbound on KRAM" ( a local commercial radio broadcast station). The flight requested an altitude assignment from which it would conduct a simulated ADF instrument jet penetration utilizing KRAM. The VFR controller assigned 755, 28 000 ft and advised it to report over the radio station. At approximately 0828, the flight reported that it was over KRAM requesting a penetration. The VFR controller cleared it for an immediate penetration and requested that it report the penetration turn. 755 then reported leaving 28 000 ft. There were no &her reports from the flight in connection with this procedure. At 0830 the offices of Aeronautical Radio at Los Angeles, Denver and Salt Lake City heard an emergency message from the United flight.. . . . " United 736, Mayday, midair collision, over Las Vegas. " At the same time, as nearly as can be determined, there was an unrecorded emergency transmission from the F-1 00F. This message was heard by the VFR controller and by the two pilots of another F-100F. All were agreed that the first portion of the emergency transmission was "Mayday, Mayday, this is 755. " The last part of the message was either, "We've had a flameout" or 'We're bailing out." The aircraft collided at 21 000 ft over a position later determined to be about 9 miles southwest of the Las Vegas VOR station, on Victor Airway 8, approximately 1-3/4 miles to the right (southeast) of the centerline. Both aircraft fell out of control and crashed killing the 47 persons on board the DC-7 and both pilots of the F-100F.

Douglas DC-7

United Air Lines Flight 718 was regularly scheduled from Los Angeles to Chicago, Illinois. On June 30, 1956, it took off from runway 25L (left) of the Los Angeles International Airport at 0904 (three minutes after TWA 2). Flight 718 was on an IFR flight plan to Chicago via Green Airway 5 Palm Springs inter-section, direct Needles, direct Painted Desert, direct Durango, direct Pueblo, direct St. Joseph. Victor Airway 116 Joliet, Victor Airway 84 Chicago Midway Airport. The flight plan proposed a .JPG"> airspeed of 288 knots., a cruising altitude of 21,000 feet, and a departure time of 0845. The flight crew consisted of Captain Robert F. Shirley, First Officer Robert W. Harms, Flight Engineer Gerard Flore, and Stewardesses Nancy L. Kemnitz and Margaret A. Shoudt. Flight preparations and dispatch of United 718 were routine and the aircraft departed with 3,850 gallons of fuel. The company load manifest showed the gross weight of the aircraft at takeoff to be 105,835 pounds, which was less than the maximum allowable of 114,060 pounds; the latter weight was restricted from a maximum of 122,200 pounds for the aircraft because of a landing limitation at Chicago. The load was properly distributed with respect to the center of gravity limitations of the aircraft. After takeoff the flight contacted the Los Angeles tower radar controller, who vectored it through the overcast over the same departure course as TWA 2. United 718 reported "on top" and changed to Los Angeles Center frequency for its en route clearance. This corresponded to the flight plan as filed; however, the controller specified that the climb to assigned altitude be in VER conditions. Flight 718 made position reports to Aeronautical Radio, Inc., which serves under contract as United company radio. It reported passing over Riverside and later over Palm Springs intersection. The latter report indicated that United 718 was still climbing to 21,000 and estimated it would reach Needles at 1000 and the Painted Desert at 1034. At approximately 0958 United 718 made a position report to the CAA communications station located at Needles. This report stated that the flight was over Needles at 0958, at 21,000 feet, and estimated the Painted Desert at 1031, with Durango next. At 1031 an unidentified radio transmission was heard by Aeronautical Radio communicators at Salt Lake City and San Francisco. They were not able to understand the message when it was received but it was later determined by playing back the recorded transmission that the message was from United 718. Context was interpreted as: "Salt Lake, United 718 . . . ah . . . we're going in."

Douglas DC-6

After a routine radio ramp check, Flight 629 taxied to runway 08R (80 degrees, right) and at 1844 the flight was in runup position where it was given ATC clearance for the flight to Portland, the first intended landing. The clearance, in part, included compulsory radio reports from the flight upon passing the Denver Omni and when climbing through 18,000 feet to its assigned flight altitude, 21,000 feet. Following takeoff the flight reported its "off time" to the company as 1852 and thereafter reported passing the Denver Omni at 1856. The latter communication was the last from the flight. About 1903 the Denver tower controllers saw two white lights, one brighter than the other, appear in the sky north-northwest of the airport and fall to the ground. Both lights were observed 30-45 seconds and seemed to fall with approximately the same speed. There was then a momentary flash originating at or near the ground which illuminated the base of the clouds, approximately 10,000 feet above. When the controllers observed the lights they initiated action to determine if any aircraft were in distress. Radio calls were made to all aircraft in the Denver area of responsibility and all except flight 629 were accounted for. It was soon learned that the flight had crashed and all 44 occupants had been killed. It was later confirmed that the disintegration of the aircraft in the air was caused by a bomb. Two weeks later, on November 15, investigators confirmed that an explosive device has been placed on board by John Gilbert Graham aged 23 who signed a US$ 37,500 life-insurance for his mother who was on board. Convicted guilty for murder and terrorism, he was sentenced to death penalty and executed on January 11, 1956.

Douglas DC-4

Flight 409 originated at New York, New York, on October 5, 1955, destination San Francisco, California, with intermediate stops including Chicago, Illinois, Denver, Colorado, and Salt Lake City, Utah. The trip to Denver was routine except for traffic delays, caused principally by weather, and the flight arrived there at 0551, October 6, one hour and 11 minutes late. Routine crew changes were made at Chicago and Denver, the last crew consisting of 'Captain Clinton C. Cooks, Jr., First Officer Ralph D. Salisbury, Jr., and Stewardess Patricia D. Shuttleworth. No discrepancies were reported by the former crew and none were found at Denver. While at Denver the aircraft was refueled to a total of 1,000 gallons of gasoline. Prior to departure Captain Cooke was briefed by the company's dispatcher on the en route weather, based on both U. S. Weather Bureau sequence reports and forecasts and the company meteorologist's forecasts and analysis. Following this briefing the flight me dispatched to Salt Lake City via airways V-4, V-118, V-6, and V-32, to cruise at 10,000 feet, and to fly in accordance with Visual Right Rules (VFR). The estimated time en route was two hours and 33 minutes. The only obligatory reporting point along the route was Rock Springs, Wyoming. The flight departed Denver at 0633, with 63 passengers, including two infants. At takeoff, the gross weight of the aircraft was 64,147 pounds, 653 pounds under the allowable weight of 64,800 pounds; an error of 100 pounds in excess of the allowable rear baggage compartment weight 2 was made in loading. Flight 409 reported its time off to the company and this was the last known radio contact with the flight. When the flight failed to report at Rock Springs at 0811, its estimated reporting time, repeated efforts were wade to establish radio contact with it. These were unsuccessful and the company then declared an emergency. A widespread search was immediately coordinated by Air Search and Rescue, which included the Wyoming Air National Guard, the Civil Air Patrol, and United Air Lines. At approximately 1140 the same day the wreckage was sighted near Medicine Bow Peak, 33 miles west of Laramie, Wyoming. The Laramie weather at 0728 was; Scattered clouds, 5,500 feet; visibility 40 miles; wind west-northwest 13 knots; snow showers of unknown intensity over the mountains. The aircraft struck the almost vertical rock cliff of the east slope of Medicine Bow Peak (elevation 12,005 feet) located in the Medicine Bow Mountains. The crash occurred at an elevation of 11,570 feet, 60 feet below the top of that portion of the mountain directly above it. Two large smudge marks were apparent on the face of the mountain. In these marks were four scars, evenly spaced and in a horizontal line, the result of the engines and propellers of the aircraft striking the cliff. At impact the aircraft disintegrated and the wreckage me strewn over a wide area. Some parts were thrown to the mountain top above the crash site, others rested on ledges at various levels, and the remainder fell to the elope below. All 66 occupants have been killed.

Douglas DC-6

N37512, under the command of Captain S. C. Hoyt, UAL New York area flight manager, departed New York International Airport at 1428 on a Visual Flight Rules flight plan for an estimated two-hour flight in the vicinity of MacArthur Field, Islip. The aircraft was properly dispatched on a routine check flight, and Captains V. H. Webb and H. M. Dozier were aboard for the purpose of receiving their periodic instrument proficiency check. Upon completion of the checks, the flight was scheduled to return to LaGuardia Airport. At 1501 the flight reported to the company by radio that they were “doing air work around Hempstead.” Another message was received by the company at 1527 reporting that the flight was going to make an ILS (Instrument Landing System) approach at Islip (MacArthur Field). Shortly thereafter, the flight contacted the MacArthur tower, requesting approval for an ILS approach and landing. Permission was granted by the tower, and a normal landing was made on runway 32. The aircraft was taxied to the intersection of runways 28 and 32 and the crew prepared for takeoff. The 1532 MacArthur weather observation showed scattered clouds at 20,000 feet, broken clouds at 25,000; visibility over 15 miles; temperature 53; dew-point 30; wind NNW at 20 knots, gusts to 30 knots. When the flight departed New York International Airport, weather was approximately the same and the forecast for the New York area indicated that it would be similar over the area for the duration of the flight. At 1548, the MacArthur controller cleared the flight to take position on runway 32 and take off. The aircraft took position on the runway but did not immediately take off, hence a second takeoff clearance was transmitted at 1550. The gross weight of the aircraft at takeoff from MacArthur Field was approximately 61,050 pounds, which was well below the maximum allowable. The load was correctly distributed with respect to center of gravity limits. The aircraft became airborne approximately, 1,500 to 1,800 feet down the runway. The takeoff appeared normal, as did the initial portion of the climb, and the aircraft remained on the runway heading. When about 50 feet high, the right wing lowered and the aircraft started turning to the right, at which time the landing gear was retracting. The aircraft continued a climbing turn and the degree of bank increased to approximately vertical by the time the heading changed about 90 degrees and the aircraft had attained an estimated altitude of 150 feet. The nose dropped sharply and the aircraft dived into the ground, striking on the right wing and nose. It then cartwheeled and came to rest right side up. An intense fire started and consumed a large portion of the wreckage in spite of the prompt arrival of fire fighting equipment on the field.

Convair CV-340

Flight 329 departed Des Moines on a VFR (Visual Flight Reed) night plan at 1608 for Omaha, Nebraska. The gross weight of the aircraft was 45,215 pounds 1,685 pounds less than the allowable 46,900 pounds. According to company records, the load was properly distributed with respect to the canter of gravity of the aircraft. The climb to 5,000 feet was uneventful but at that altitude the crew noticed vibration and a slight fore-and-aft movement of the control column. The climb was continued to 6,000 feet, where the aircraft was leveled off and power was reduced. As the vibration was still present at this time, the captain attempted to dampen it by engaging the autopilot; however, this was unsuccessful and it was immediately disengaged. The first officer next lowered the flaps, first to 5 degrees and then to 15 degrees, without any noticeable effect. The “Fasten Seat Belt" sign was turned on and the captain told the first officer to advise the company of their difficulty via radio. About this time a sudden failure in the control system was felt and it was with extreme difficulty that any semblance of elevator control was maintained. The first officer again tried lowering the flaps, this time to the 24-degree position, but as this did not help to maintain control he returned them to the 15-degree position, where it was found the most favorable results were attained. Accordingly, the first officer transmitted "Mayday” (distress call) on the radio and said that they were attempting to return to Des Moines but were experiencing control trouble. The buffeting became so severe it was then necessary for the copilot to help the can hold the control column. However, the buffeting lessened and the captain advised the first officer to depressurize the aircraft and tell the stewardess to prepare the passengers for an emergency landing. This was done. By that time the aircraft had descended below 3,000 feet. Both throttles were retarded in turn to see if the trouble could possibly be caused by one of the engines. This also proved to no avail. The vibration built up to high level and suddenly another failure in the control system was felt and the air-plane went into a steep climb. As it seemed that a stall was imminent, the captain quickly moved the propellers to a high r. p. m. and pushed the throttles forward until about 50 inches of manifold pressure was seen on the gauges. The airplane then nosed over and began to dive at a very steep angle. During this rapid descent the captain reduced power and headed toward open country to his right. When the aircraft reached 500 feet above the ground the captain was successful in flaring the aircraft and it struck the ground in a flat attitude. All occupants were quickly deplaned as soon as the aircraft stopped.

Douglas DC-3

United Air Lines operates a Flight Training Center at Denver, Colorado, to train applicants for first officer positions with the company. The crew of United Trainer 16 consisted of Senior First Officer Jordan D. Kocher, who had been designated by United Air Lines as captain and instructor, and Trainee First Officers Laurence G. Wilson and Wayne C. Moen. The flight departed Stapleton Airfield at 0655LT. The 0628 weather conditions, upon which the crew had been briefed, were ceiling measured 15,000 feet, visibility 25 miles, and wind northwest 14 knots Ceiling and visibility were unlimited at the time of the accident, with the wind northwest 16 knots. No radio contacts were made by United Trainer 16 after reporting departure time. It was cleared for a training flight of four hours’ duration within a 25-mile radius of Denver Captain Kocher occupied the left pilot’s seat at takeoff. Upon departure, the aircraft load, in addition to the crew, was 820 gallons of gasoline, full oil tanks, and 650 pounds of sand ballast tied down in the rear baggage pit. The load was properly distributed with relation to the aircraft’s center of gravity, and the 22,910-pound gross weight at takeoff was within allowable limits. Witnesses reported that at between 0720 and 0725 the aircraft was seen to stall, enter a spin, and strike the ground in a diving attitude before recovery was effected.

Boeing 377 Stratocruiser

The flight departed San Francisco at 1042, operating as "United Trainer 7030." Flight Manager Frederick S. Angstadt was captain and was being given his semi-annual instrument check by Assistant Flight Manager Hugh C. Worthington, who served as copilot. Flight Engineer Charles K. Brogden was the third crew member. In addition to the foregoing instrument check, consideration had been given to investigating the feasibility of using the Oakland, California, Municipal Airport for certain phases of crew training in this type aircraft for a new class of pilots and flight engineers which was to convene that afternoon. Captains Angstadt and Worthington were to supervise this training. United Air Lines' officials stated that Captains Angstadt and Worthington intended to make this determination during the flight. Captain Angstadt was given the 0928 sequence weather reports for the local area prior to completing a clearance form at the UAL dispatcher's office. Pertinent weather was as follows: stratus clouds in the Bay area with tops at approximately 1,600 feet; San Francisco and Oakland - 800 foot ceiling, overcast, visibility three miles, haze and smoke; ceiling and visibility at Fresno and Sacramento unlimited. The forecast for the Bay area indicated scattered clouds by 1100 PST. Clearance was issued for local flight under Visual Flight Rules (VFR), confined to a 100-mile radius from San Francisco and under 10,000 feet. The load was properly distributed with respect to permissible center of gravity limits. Gross weight of the aircraft at takeoff was 114,886 pounds with 4,700 gallons of fuel, well under the maximum permissible gross takeoff weight. After reporting on top of the broken scattered clouds to the San Francisco tower at 1046, the flight proceeded to Oakland. The Oakland tower approved a simulated Instrument Landing System approach; this and a missed approach procedure were performed. The flight again reported on top at 1136. Another simulated ILS approach was requested of the Oakland tower but the flight was advised that there would be a delay due to other traffic. In view of this, the pilot decided to return to San Francisco. The flight changed frequency from the Oakland tower to San Francisco Approach Control at 1137. At 1139, the flight was cleared for an ILS approach to the San Francisco Airport, but did not acknowledge the clearance on the 119.1 megacycle Approach Control frequency. Following two attempts to contact the flight, the controller heard the aircraft make an unreadable call on 121.9 megacycles, and instructed the flight to listen on 119.1. This transmission was followed by further instruction for the flight to hold VFR, and stand by. The frequency change was apparently accomplished by the flight and the pilot again requested permission to make a simulated ILS approach. The request was granted, with instructions to report upon leaving the ILS outer marker inbound. This message and one other were not acknowledged by the flight. No emergency call was received from the aircraft. The crash was reported to the U. S. Coast Guard Air Station at 1046 by the manager of a nearby airport.

Douglas DC-6

Air Route Traffic Control (ARTC) cleared Flight 615 on an instrument flight plan from Chicago to Oakland, and from Oakland to San Francisco in accordance with Visual Flight Rules (VFB). Altitude was to be 18,000 feet man sea level (MSL) via Red Airway 4, Creen Airway 3, and Red Airway 6 from Chicago to Denver, direct to Milford, Utah, and thence direct to Oakland. Flight between Oakland and San Francisco was to have been via Green Airway 3 at 500 feet. Routine radio contacts were made en route. At 0354, August 24, while approaching the Oakland area, Flight 615 was cleared to the Newark, California fan marker, with instructions to descend to 6,000 feet, maintain that altitude, and contact Oakland Approach Control over Altamont, California. At 0411, the flight reported over Stockton, California, at 9,500 feet, descending. At this time the flight was given, and acknowledged, the Oakland altimeter setting of 29 88 inches. Flight 615 reported over the Altamont Intersection at 0416, and made initial contact with Oakland Approach Control one-half minute later. Clearance of the flight into Oakland was now vested in Approach Control, and no further radio contacts were made with company communications. The flight was cleared by Approach Control to the Oakland radio range station to maintain at least 500 feet above the tops of the clouds. The pilot followed this contact with a request for clearance direct to Newark and a straight-in range approach. The Newark fan marker and compass locator lie on the southeast leg of the Oakland radio range This request was granted, with instructions to maintain an altitude of 500 feet on top of the cloud layer between Altamont and Newark. At 0422, the flight reported approaching the Hayward, California, compass locator, which is between Newark and Altamont, and requested a second modification to clearance instructions by asking for a straight-in ILS (Instrument Landing System) approach 2. Approach Control advised it to stand by due to another aircraft in the area. Flight 615 shortly thereafter advised Approach Control that it was approaching Newark and to disregard the request for an ILS approach. At 0425 Flight 615 was cleared for a straight-in approach on the southeast course of the Oakland radio range from Newark. At 0427 the flight reported leaving Newark inbound to Oakland. This was the last radio contact. A minute later, the four engine aircraft struck the Tolman peak (985 feet high) located about 14,6 miles southeast of Oakland Airport. The aircraft was destroyed by impact forces and all 50 occupants were killed.

Douglas DC-6

Flight 610 of June 29, 1951, originated in San Francisco, California, and was scheduled to Chicago, Illinois, with en route stops, among which were Oakland, California, Salt Lake City, Utah, and Denver, Colorado. The crew consisted of Captain J R Appleby, First Officer H G Tower, Flight Engineer A T Petrovitch, and Stewardesses C J Baymond and F M Smith. The flight departed San Francisco on schedule at 1915 and after stopping at Oakland proceeded to Salt Lake City, arriving there at 2324. It departed Salt Lake City at 0011, June 30, 1951, 26 minutes behind schedule due to the reloading of bulky cargo At the time of departure the aircraft weighed 78,597 pounds, which was within the certificated gross take-off weight of 79,380 pounds, the load was properly distributed with respect to the center of gravity. There were five crew members, forty-four adult passengers and one infant on board. The approved flight clearance indicated an IFR flight, via Bed Airway 49, Green Airway 3, and Amber Airway 3, to Denver at a cruising altitude of 15,000 feet, with Omaha, Nebraska, designated as the alternate airport. The flight proceeded in a routine manner and at 0104 reported over Rock Springs, Wyoming, at 15,000 feet, estimating its arrival over Cheyeme, Wyoming, at 0147 and over Denver at 0207 2 Forty-three minutes later, at 0147, the flight reported having passed the Silver Crown fan marker (located 12 miles west of Cheyenne) and requested a lower altitude Accordingly, a new clearance was immediately issued-"ARTC clears United 610 to Dupont intersection, 3 descend to 8500 feet immediately after passing Cheyenne, maintain 8500 feet, no delay expected, contact approach control over Dacono "4 This clearance was acknowledged and the flight reported that it was over Cheyenne at 0147, at 15,000 feet and was now starting to descend. The Denver altimeter setting was then given the flight as being 30 19 inches. Nine minutes later, at 0156, the flight reported reaching its assigned altitude of 8,500 feet No further communication was received from the flight. At 0200, the Denver Control Tower requested the company radio operator to advise the flight to call approach control Repeated calls were made without an answer. It was later determined that Flight 610 had crashed on a mountain (Mt Crystal) 18 miles west-southwest of Fort Collins, Colorado. All 50 occupants were killed.

Douglas DC-3

Flight 129 departed Cleveland, Chic, at 1807, April 28, 1951, for Chicago, Illinois, with stops scheduled at Fort Wayne and South Bend, Indiana The crew consisted of Captain E K Swallow, First Officer H R Miller, and Stewardess Beverly Fllis, there were eight passengers on board at the time of departure The aircraft weighed 24,180 pounds, which was within the certificated gross weight limit of 25,320 pounds, and the load was properly distributed A flight plan filed by the crew with ARTC (Air Route Traffic Control) indicated an IFR (instrument flight rule) flight at a cruising altitude of 4,000 feet with South Bend and Toledo, Ohio, designated as the alternate airports The "Trip Weather Analysis" (a form prepared by the crew before departure) indicated that scattered cumulus and thunderstorms were expected south of the course to Fort Wayne Also, that a squall line extending in a north-south direction was moving eastward across Illinois and Indiana at an estimated speed of 35 miles per hour and was expected to be in the vicinity of South bend upon the flight's arrival there. After takeoff, Flight 129 was advised by company radio that it was cleared by ARTC via Green Airway No 3 over Sandusky, Ohio, to the Toledo range, to maintain 3,000 feet and to contact Toledo approach control upon arriving there Flight 129 advised they were going to Fort Wayne and not Toledo Accordingly, ARTC amended the flight's clearance to proceed to Fort Wayne via Green Airway No 3 and Blue Airway No 44 and to maintain 4,000 feet The flight proceeded and a routine company radio report was made when over Sandusky At 1847, the flight reported over Toledo and estimated its arrival Fort Wayne at 1932 At this time, the Fort Wayne 1830 weather sequence report was given the flight which was, "ceiling estimated 25,000 feet, thin Broken clouds, visibility 0 miles, wind southwest 5 miles per hours "Seventeen minutes later at 190', flight 129 called Toledo tower and requested, through APTC permission to cruise at 2,300 feet because of turbulent conditions This was not approved because of other traffic At 1920 the flight reported it was approaching Fort Wayne and was changing to tower frequency The flight reported again when nineteen in less northeast of Bauer Field and was advised at Runway 22 was the runway in use and that the wind was five to ten miles per hour from the southwest At the time this transmission was made there was a moderate amount of station and the flight reported "We are not recanting you very clearly but I think you said, `Straight 11 runway 22' We will call later, closer in ". Because of thunderstorm activity in the area, three other aircraft were requesting instructions to land at approximately the time Flight 129 was making its approach Two of these aircraft landed successfully and the pilot of one, upon request, advisee the tower that the thunderstorm was approximately ten miles west of the airport. At the time the four aircraft were approaching Baer Field, United *** 12 degrees was number four to land in the traffic pattern immediately behind *** World Airlines' Flight 240, a DC-3 aircraft then these latter aircraft were approximately one and two and one-half miles, respectively, from the approach end of Runway 22, the wind at the airport shifted to west-northwest and increased in velocity from 5-10 miles per hour to 40 miles per hour Both flights were advised by the tower of the sudden change of wind direction and increased velocity, and a landing on Runway 27 was suggested, it being more nearly into the wind Upon receiving this message the flights immediately turned to the left to align with this runway. When these aircraft were east of the airport the wind increased to 60-65 miles per hour with gusts to 85 miles per hour and a heavy rainfall began, accompanied by lightning and severe static The flights were quickly advised of the weather change but, due to the sudden decrease in visibility, neither flight was seen again by the tower Flight 129 immediately advised, "United 129 heading east" This was closely followed by a message from TWA's 240, "Pulling out" In order to avoid a possible collision the tower then requested separation altitudes for these aircraft from Chicago ARTC and was advised that Flight 129 was assigned an altitude of 4,000 feet and that Flight 240 was assigned 3,000 feet Both clearances were broadcast from the tower several times without acknowledgment. At 1932 m orange-colored flash was seen to the east-southeast from the tower It was later determined that United's Flight 129 had crashed in a field 2 6 miles east-southeast of the airport TWA's Flight 240 proceeded safely to Toledo. The aircraft disintegrated on impact and all 11 occupants were killed.

Douglas C-47 Skytrain (DC-3)

The crew was engaged in a local training sortie in Oakland Airport. Shortly after takeoff, while climbing, the right engine suffered a loss of power. The captain informed ATC and elected to return for an emergency landing but the aircraft stalled, hit tree tops and crashed in a wooded area located in Alameda, north of the airport. The aircraft was destroyed and all three crew members were injured.

Douglas DC-6

The airplane arrived in Chicago at 0952LT, en route from Los Angeles to New York City. At Chicago, the airplane was given a routine station inspection, serviced, loaded, and the flight departed for New York with a new crew at 1044. Aboard were 39 passengers, a crew of four, 2,568 pounds of cargo and 1,800 gallons of fuel, all properly loaded. The resulting total airplane weight was within the certificated gross weight. The airplane climbed en route to its planned altitude of 17,000 feet, proceeding on course, and at 1155 the captain reported to the company radio at LaGuardia Field, that the airplane was mechanically "okay” for a return trip. A routine report was made over Phillipsburg, PA, approximately 500 miles east of Chicago, at 1223, and at 1227 the crew made a routine acknowledgment of a clearance to descend en route to an altitude between 13,000 and 11,000 feet. Four minutes later, at 1231, the company radio operator at LaGuardia Field heard a voice which did not identify itself calling loudly and urgently. Another United crew in a DC-3, flying over the same route behind Flight 624 and at a different altitude, heard what they termed “screaming voices” calling "New York." Then, after an unintelligible transmission, “This is an emergency descent." Inasmuch as all other air carrier flights in the vicinity at this time were accounted for, this transmission undoubtedly emanated from Flight 624. The airplane was first observed by ground witnesses 31 miles northwest of the scene of the accident flying a southeasterly heading toward Shamokin, PA. The airplane flew over the Sunbury Airport, at approximately 4,000 feet above the ground on a southeasterly heading. Immediately north of Shamokin the airplane, then only 500 to 1,000 feet above the ground, described a shallow left turn. The course was toward constantly rising terrain, the hills around Sunbury being 900 feet in elevation and the hills around Shamokin being approximately 1,600 feet in elevation. Five miles east or beyond Shamokin the airplane, flying only 200 feet above the ground, entered a right climbing turn. As it passed to the north of Mount Carmel, the climbing turning attitude increased sharply. The airplane then struck a hillside at an elevation of 1,649 feet. The aircraft disintegrated on impact and all 43 occupants were killed.

Douglas DC-6

Flight 608 departed Los Angeles, California, at 1023 with its destination Chicago, Illinois, to cruise at 19,000 feet according to visual flight rules. Routine position reports were made over Fontana, Daggett and Silver Lake, California; Las Vegas, Nevada; and Saint George, Utah. During the latter report, the flight indicated that it estimated passing over Bryce Canyon, Utah, at 1222. At 1221 Flight 608 reported that a fire had been detected in the baggage compartment which the crew was unable to extinguish. The report added that the cabin was filled with smoke and that the flight was attempting to make an emergency-landing at Bryce Canyon Airport. Shortly thereafter the flight again reported that the “tail is going out--we may get down and we may not.” At 1226 another transmission was received from the flight indicating that it was going into the “best place” available. One minute later the flight reported “we may make it--approaching a strip.” No further contact was had from the flight. Witnesses who observed the aircraft as it was approaching Bryce Canyon from approximately 20 miles southwest first observed what appeared to be white smoke streaming from the aircraft, followed later by dense black smoke. The first witnesses who observed fire in the bottom of the aircraft at approximately the center-section were located approximately 15 miles south of Bryce Canyon. Until shortly before the moment of impact, the aircraft appeared to be under normal control; however, no witnesses were located who observed the crash.

Douglas DC-4

Flight 521 taxied from its parked position, rolled onto Runway 18, and without pause or hesitation accelerated for take-off. The throttles were advanced. Air speed increased to above 90 miles per hour. Captain Baldwin applied back pressure to the control column, but the "feel" of the controls was "heavy," and the aircraft did not respond. As the aircraft raced toward the boundary of the field, Captain Baldwin decided to discontinue his take-off. About 1,000 feet from the south and of the runway he applied brakes, ordering the co-pilot at the same time to cut the engines. A ground-loop was attempted by heavy application of left brake. The aircraft, however, proceeded to roll straight ahead. Then, in the both brakes locked it continued over the remainder of the runway, crashed through the fence at the airport boundary, and half-bounced, half-flew across the Grand Central Parkway. The aircraft finally came to rest immediately east of the Casey Jones School of Aeronautics, a distance of 800 feet from the end of Runway 18 and 1,700 feet from the point at which brakes were first applied. It was almost immediate enveloped in flames. The captain, another crew member and three passengers were rescued while 43 other occupants were killed.

Douglas DC-3

Ground accident. Exact circumstances unknown. No casualties but aircraft written off.

Douglas DC-4

The four engine aircraft landed on a wet runway. After touchdown, it was unable to stop within the remaining distance, overran and came to rest 200 feet further on. All 45 occupants were uninjured and quickly disembarked while the aircraft was considered as damaged beyond repair due to severe damages to the fuselage.

Douglas C-53 Skytrooper (DC-3)

The aircraft was heard southwest of the airport at 0327 and at this time Cleveland Tower cleared the flight to land on Runway 36-Left. At 0328 the air-craft was observed over the airport at an altitude of between 200 and 400 feet flying In a northeasterly direction. When approximately over the north boundary, the aircraft disappeared from view in what appeared to be a low cloud formation. At this time Cleveland Tower advised the flight that It was cleared to use Runway 36-Left, Runway 36-Right, or Runway 31, at the captain's discretion. The aircraft was next seen re-approaching the airport from the northeast in a right turn, during which turn the landing lights were switched on. In the latter part of the turn, a descent was established and this descent was continued in a northwesterly direction toward the dark, undeveloped area north of the airport. With the exception of the fact that the aircraft was heading toward an area not within the boundary of the airport, its appearance was that of an aircraft in a normal landing approach. When at an altitude of approximately 30 feet, the aircraft banked slightly to the left and, immediately thereafter it struck trees and high tension lines paralleling the north boundary of the airport. The aircraft veered sharply to the right and dived into the ground, coming to rest approximately 550 feet beyond the point of initial contact.

Douglas DC-4

An approach from the west was then decided on by the Captain as visibility there had been fair. The First Officer contacted the tower and was cleared to land on Runway 12 (to the southeast). While headed west the Captain started a gradual left turn at the western boundary of the field, continued it for a short time and then entered a right turn in an attempt to line up with and land on Runway 12. This right turn was continued at an altitude of some 200 feet above the ground with, wheels down, 15 degree of flap and airspeed of approximately 120 mph (once as low as 110 mph). The Captain instructed the First Officer, who occupied the right hand pilot seat, (on the low and field side of the turn) to "sing out" when he saw the field. When the First Officer did see it he said "There's the field at 2 o'clock" (at a relative bearing of 60 degree). The Captain then leaned to the right to see the field himself and during this momentary diversion from the instruments enough altitude was lost to permit the right wing tip to strike the ground. The site was on rolling prairie approximately 20 feet higher than, and about 1 1/2 miles northwest of the Cheyenne Airport, on the U. S. Military Reservation of Fort Warren. At the instant of impact the aircraft was still in a right turn, banked approximately 15 degree and headed northeast. It came to rest about 700 feet beyond the point of first impact. A gasoline fire developed on the ground along the crash path and the right wing, which had been torn from the fuselage, was partly burned. Two passengers were killed while most of the other occupants were injured, some of them seriously.

Douglas C-54 Skymaster

The crew was performing a local training mission consisting of approaches, landings and touch and goes. On final approach, during the last segment, the aircraft was in an excessive rate of descent and hit violently the runway surface. All undercarriage and both wings were sheared off and the aircraft came to rest. All four crew members who were carrying a check flight were injured. The aircraft was written off.

Douglas DC-3

On the non stop leg from Boise to Denver, while flying by night and poor visibility, the aircraft hit the slope of Mt Elk located southeast of Elk Mountain, south Wyoming. The wreckage was found few hours later in a deep snow and in poor weather conditions, about 340 feet from the summit. The aircraft was destroyed by impact forces and all 21 occupants were killed. At the time of the accident, the aircraft deviated from the prescribed flight path by 4,5 miles and its altitude was 11,000 feet.

Consolidated B-24 Liberator

United Airlines was performing this special flight from New Zealand to Brisbane on behalf of the US Consulate in order to rapatriate in Australia some Japanese and Thai refugees who should be swapped with US soldiers. Shortly after take off from runway 04 by night, the aircraft climbed in light rain and soft fog and went above the stratus layer when it banked left. It lost altitude, hit the ground at a speed of 200 knots, bounced twice and eventually crashed in a mangrove. On site, SAR could evacuate 16 injured persons while 14 other occupants were killed. A day later, two of the survivors died from their injuries. USAF confirmed that three of the crew and thirteen passengers were killed. All passengers were essentially women and children returnees.

Douglas DC-3

The crew was conducting a training exercise on behalf of the USAAF. While flying in the vicinity of the Oakland Municipal Airport, the aircraft caught fire for unknown reason. The crew attempted to make an emergency landing but the aircraft crashed in flames and was destroyed by fire. Both occupants were injured.

Douglas DC-3

On final approach to the Wright-Patterson AFB, on of the wing hit a tree. The aircraft stalled and crashed in flames. All three crew members were killed. They were completing a cargo flight on behalf of the USAAF. For undetermined reasons, the aircraft was approaching too low.

Douglas DC-3

On approach to Salt Lake City Airport at night and in poor weather conditions, pilots did not realise they were flying too low. Aircraft hit a mountain slope few km short of runway and was destroyed by impact forces. All 17 occupants were killed.

Douglas DC-3

On final approach to Chicago-Midway Airport, at an altitude of 160 feet, the aircraft stalled and crashed short of runway. All three crew members and seven passengers were killed. Crew: Philip Cramer Scott, pilot, George Sumner Young, copilot, Florence Little, stewardess.

Douglas DC-3

While cruising in snow falls, the aircraft hit the Bountiful Peak located in the Wasatch mountain range, some five km northeast of Centerville. SAR arrived on the scene around 0900LT. The aircraft was destroyed by impact forces and all ten occupants were killed.