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Rotary Aircraft

Altitude Mishaps

Since the inception of the airmobility concept, every Army Aviation deployment has been to areas of high density altitude, mountainous terrain, or both - every single one. Yet there is no mandatory, standardized training for these conditions. Any in-depth look at the history of deployments, particularly combat deployments, will reveal that maximum gross weight operations are the norm rather than the exception. Again, with the exception of the HAATS and it's Power Management Training System, no formalized training addresses maximum gross weight operations.

Below are some actual yet typical examples resulting from failures to either recognize aircraft or environmental limitations or to execute at the required level of proficiency.

  • AH-1F While engaged in aerial gunnery training at Army training area, the aircraft encountered a settling with power condition. After leaving the FAARP, the PIC conducted an OGE hover check. Upon completion of this check he proceeded from a 50-foot hover and encountered an uncommanded descent which was unrecoverable with a 125% torque. The main rotor struck a 55' pine tree and the aircraft fell vertically to a dirt road.
  • AH-1F While at stationary OGE hover, firing 2.75 FFAR rockets, the aircraft began an uncommanded right turn. At the 90-degree point, the turn rate rapidly increased. The aircraft completed 2 1/2 turns, impacted the ground, bounced, rotated an add'l 120 degrees impacted again, and rolled to the left, coming to rest inverted.
  • AH-64 Apache During a mountain approach, on short final the low RPM warning light illuminated. The aircraft lost altitude and impacted the side of the mountain. A post crash fire destroyed the aircraft. Both crewmembers were evacuated via CH-47.
  • AH-64 Apache While in a steep, near 60-degree left turn, the AH-64A PIC detected a high closure rate with the terrain and attempted an unsuccessful recovery. The aircraft made ground contact in a nose-up attitude and was extensively damaged. The crew escaped injury.
  • CH-54 During takeoff from a 9700' PZ, the aircraft began to settle toward the ground. Rotor RPM decayed to 94%. The pilot attempted to extend his flight path to avoid personnel. Aircraft struck the ground on a heading of 360 degrees. The main rotor blades made contact with the hillside, the aircraft spun right 200 degrees, rolled left 60 degrees, coming to rest on its left side.
  • MH-6E While attempting to negotiate a route through 7800' MSL mountain saddle, the engine failed to produce sufficient power to continue flight. Airspeed was reduced in an attempt to continue the climb and the flight through the saddle. When it was determined flight could no longer be continued. A right turn was initiated, available power continued to deteriorate. The pilot initiated an autorotation and the aircraft descended into 10' high trees on an approx. 25 degree slope facing downslope. The aircraft remained upright and the crew exited from their respective doors unassisted.
  • OH-58A While on landing approach to a pinnacle, pilot descended through demarcation line. Aircraft began to settle, pilot over-torqued the aircraft in attempt to arrest rate of descent. He landed at nearest clearing.
  • UH-1H While making an approach to a ridgeline in mountainous terrain, the pilot experienced an RPM droop and attempted to go around. As the aircraft turned left, the RPM continued to deteriorate and the aircraft struck the ground upright and rolled on it's left side.
  • UH-1V During a day, MAST mission and while on final approach to an unimproved landing site at 11,400' MSL, the UH-1V crew encountered an uncommanded right yaw condition. The aircraft struck the ground and rolled 90 degrees coming to rest inverted.
  • UH-1V On final approach for landing to a mountain top, 12,300' MSL, aircraft encountered rapid uncommanded right spin over the edge of a pinnacle. Pilot applied right cyclic and reduced collective, in effort to fly out of condition. The aircraft assumed a nose-low attitude and continued to spin. Approx. 100 feet below crest of pinnacle, the main rotor blades impacted the ground, followed by the fuselage. The mast and blades separated, the aircraft rolled downslope 1000', coming to rest on it's left side, almost inverted.
  • UH-6OL PIC was tasked to slingload an M998, HMMWV. Two attempts were made but vehicle was too heavy for aircraft. Equipment and passengers were unloaded and a third attempt was made. Aircraft was able to lift vehicle to a ten-foot hover, then slide left to get away from other parked vehicles. Aircraft then made a climbing left turn towards the active runway. At 100 feet AGL, the PIC stopped forward movement to allow the pilot to obtain take off clearance from the tower. The aircraft did not have sufficient power to hover OGE with a sling load and the low rotor audio sounded. The aircraft began to descend and became engulfed in brown out conditions at approx. 30 feet AGL. The vehicle hit the ground, then was dragged along the ground to the left. The PIC tried to manually jettison the load but was unable. The pilot used the emergency jettison switch and the vehicle was dropped and the aircraft flew out of the dust cloud and landed safely.

It is a medical fact that during periods of high stress (and the stress of high DA, max gross weight, mountainous, NVG, and combat ops would certainly qualify) our perceptual field narrows or collapses. It is our training that comes to the fore and determines the result of our endeavors. If our training, our habit formation (both in recognition and response), is weak then so is our execution. It has been demonstrated using the Power Management Training System that no matter how aware a crew is as to what the correct control input should be, under pressure they usually cannot overcome bad habits to actually accomplish the intent.



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Page last modified: 07-07-2011 02:35:20 ZULU