Hawaii Air Ambulance

Cessna 414 Chancellor

The twin-engine medical transport airplane was on a positioning flight when the pilot reported a loss of power affecting one engine before impacting terrain 0.6 miles west of the approach end of the runway. The airplane was at 2,600 feet and in a shallow descent approximately 8 miles northwest of the airport when the pilot checked in with the tower and requested landing. Three and a half minutes later, the pilot reported that he had lost an engine and was in a righthand turn. Radar data indicated that the airplane was 2 miles southwest of the airport at 1,200 feet msl. The radar track continued to depict the airplane in a descent and in a right-hand turn, approximately 1.9 miles west of the approach end of the runway. The altitude fluctuated between 400 and 600 feet, the track turned right again, and stabilized on an approximate 100- degree magnetic heading, which put the airplane on a left base for the runway. The track entered a third right-hand turn at 500 feet. The pilot's last transmission indicated that one engine was not producing power. The last radar return was 6 seconds later at 200 feet, in the direct vicinity of where the wreckage was located. Using the radar track data, the average ground speed calculations showed a steady decrease from 134 knots at the time of the pilot's initial report of a problem, to 76 knots immediately before the airplane impacted terrain. The documented minimum controllable airspeed (VMC) for this airplane is 68 knots. The zero bank angle stall speed varied from 78 knots at a cruise configuration to 70 knots with the gear and flaps down. A sound spectrum study using recorded air traffic control communications concluded that one engine was operating at 2,630 rpm, and one engine was operating at 1,320 rpm. Propeller damage was consistent with the right engine operating at much higher power than the left engine at the time of impact, and both propellers were at or near the low pitch stops (not feathered). Examination and teardown of both engines did not reveal any evidence of mechanical malfunction. Investigators found that the landing gear was down and the flaps were fully deployed at impact. In this configuration, performance calculations showed that level flight was not possible with one engine inoperative, and that once the airspeed had decreased below minimum controllable airspeed (VMC), the airplane could stall, roll in the direction of the inoperative engine, and enter an uncontrolled descent. The pilot had been trained and had demonstrated a satisfactory ability to operate the airplane in slow flight and single engine landings. However, flight at minimum controllable airspeed with one engine inoperative was not practiced during training. The operator's training manual stated that during single engine training an objective was to ensure the pilot reduced drag; however, there was no procedure to accomplish this objective, and the ground training syllabus did not specifically address engine out airplane configuration performance as a dedicated topic of instruction. The operator's emergency procedures checklist and manufacturer's information manual clearly addressed the performance penalties of configuring the airplane with an inoperative engine, propeller unfeathered, the landing gear down, and/or the flaps deployed. The engine failure during flight procedure checklist and the engine inoperative go-around checklist, if followed, configure the airplane for level single engine flight by feathering the propeller, raising the flaps, and retracting the landing gear.

Cessna 414 Chancellor

The airplane collided with trees and mountainous terrain at the 3,600-foot-level of Mauna Kea Volcano during an en route cruise descent toward the destination airport that was 21 miles east of the accident site. The flight departed Honolulu VFR at 0032 to pickup a patient in Hilo, on the Island of Hawaii. The inter island cruising altitude was 9,500 feet and the flight was obtaining VFR flight advisories. At 0113, just before the flight crossed the northwestern coast of Hawaii, the controller provided the pilot with the current Hilo weather, which was reporting a visibility of 1 3/4 miles in heavy rain and mist with ceiling 1,700 feet broken, 2,300 overcast. Recorded radar data showed that the flight crossed the coast of Hawaii at 0122, descending through 7,400 feet tracking southeast bound toward the northern slopes of Mauna Kea and Hilo beyond. The last recorded position of the aircraft was about 26 miles northwest of the accident site at a mode C reported altitude of 6,400 feet. At 0130, the controller informed the pilot that radar contact was lost and also said that at the airplane's altitude, radar coverage would not be available inbound to Hilo. The controller terminated radar services. A witness who lived in the immediate area of the accident site reported that around 0130 he heard a low flying airplane coming from the north. He alked outside his residence and observed an airplane fly over about 500 feet above ground level (agl) traveling in the direction of the accident site about 3 miles east. The witness said that light rain was falling and he could see a half moon, which he thought provided fair illumination. The area forecast in effect at the time of the flight's departure called for broken to overcast layers from 1,000 to 2,000 feet, with merging layers to 30,000 feet and isolated cumulonimbus clouds with tops to 40,000 feet. It also indicated that the visibility could temporarily go below 3 statute miles. The debris path extended about 500 feet along a magnetic bearing of 100 degrees with debris scattered both on the ground and in tree branches. Investigators found no anomalies with the airplane or engines that would have precluded normal operation. Pilots for the operator typically departed under VFR, even in night conditions or with expectations of encountering adverse weather, to preclude ground holding delays. The pilots would then pick up their instrument flight rules (IFR) clearance en route. The forecast and actual weather conditions at Hilo were below the minimums specified in the company Operations Manual for VFR operations.