On June 28, 2019, about 1608 Alaska daylight time, a Maule M-6-235 sustained substantial damage when it was involved in an accident about seven miles northwest of Moose Pass, Alaska. The commercial pilot and two passengers were fatally injured, and one pilot-rated passenger was seriously injured.
The flight departed Big Johnstone Lake near Seward, Alaska, about 1529, and was destined for Lake Hood in Anchorage.
The pilot-rated passenger, who was in the right front seat, stated that she had been manipulating the flight controls but that the visibility deteriorated as the flight progressed, so the pilot assumed control of the airplane. She added the pilot seemed stressed due to the deteriorating conditions and that the occupants discussed locating an alternate landing spot.
The pilot-rated passenger was looking out the right side of the airplane for terrain, and the pilot was looking out the left side to try to follow Sterling Highway. She stated that forward visibility was “not very good at all” but that she was able to see straight down.
She also stated that the right passenger door popped open, creating a momentary distraction, and that she was able to hold the door shut.
The airplane then entered an unusual attitude, and another passenger began yelling, “pull-up, pull-up,” to which the pilot responded, “I’ve got this.” The pilot-rated passenger’s last recollection of the flight was recognizing that the airplane was in a stall and hearing the stall warning horn.
The GPS data logs for the day of the accident revealed that, about 1602, the airplane crossed Moose Pass at a GPS altitude of about 2,000 feet. The airplane continued northwest along Sterling Highway at GPS altitudes that varied between 1,700 and 2,400 feet.
About 1606, after passing the intersection of Sterling and Seward Highways, the airplane began a right 180° turn to the southeast. Shortly after, it began a descent to a GPS altitude of 1,215 feet. At 1607:00, the airplane began a left turn toward a northerly heading and initiated a climb. At 1607:34, the airplane was on a track of 354° at a GPS altitude of 2,032 feet, and at a groundspeed of 37 knots. The last fully recorded in-flight data point was at 1608:01, when the airplane was at a GPS altitude of 1,587 feet and a 0-knot groundspeed and on a track of 282°.
A witness was outside shortly after 1600 on the day of the accident and heard an airplane flying overhead. He stated that the airplane sounded as if it was flying west to east and as if it was “maneuvering under power.” About 15 seconds later, all airplane-related sounds ceased. He also stated that the smoke from a nearby wildfire was very thick at his location, resulting in a vertical visibility of about 100 feet and a horizontal visibility of about 1/4 mile.
According to the Alaska Rescue Coordination Center, a 406-MHz emergency locator transmitter (ELT) signal was received at 1614, and rescue personnel from the Air National Guard’s 210th Air Rescue Squadron in Anchorage, began a search for the source of the ELT signal. An Air National Guard HH-60G helicopter crew discovered the accident, and the surviving passenger was transported to a medical facility for treatment.
A review of FAA weather camera images recorded from Moose Pass (52Z), about seven miles southeast of the accident site, revealed reduced visibilities in all directions about the time of the accident as a result of smoke and/or haze in the area.
All the airplane’s major components were located at the main wreckage site. The cockpit and cabin area exhibited extensive aft crushing. The engine, firewall, and instrument panel were displaced upward and aft. The throttle and propeller were found near the full forward position, and the mixture was found in the idle cutoff position. The fuel selector was found in the “OFF” position.
The right wing remained attached to the fuselage but exhibited leading edge crushing damage outboard near the tip. The right aileron and right wing flap remained attached and were relatively undamaged. The right auxiliary and main fuel tank caps were in place and secure. Fluid was observed in the right auxiliary fuel tank. No fluid was observed in the right main fuel tank.
The left wing remained attached to the fuselage. The left aileron and left wing flap remained attached to their respective attach points but sustained impact damage. The left auxiliary and main fuel caps were in place and secure. Fluid was observed in the left auxiliary and left main fuel tanks.
Flight control continuity was verified from the cockpit in the direct cables and balance cable to the left and right ailerons.
The engine remained attached to the airframe. The propeller remained attached to the crankshaft flange, the blades remained attached to the propeller hub assembly, and the crankshaft separated about 1 inch behind the flange. Both blades exhibited substantial leading edge gouging and torsional “S” twisting.
The pilot-rated passenger reported no mechanical malfunctions with the airplane or its systems, and the on-scene examination revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation.
Probable Cause: The pilot’s geographic disorientation and his exceedance of the airplane’s critical angle of attack while maneuvering to avoid mountainous terrain, resulting in an aerodynamic stall.
This June 2019 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.