Alaska News

Report on Merrill Field crash highlights pilot decision-making

A chain of events that included fuel starvation, loss of engine power and an aerodynamic stall caused the crash that killed two people at Merrill Field in August 2013, according to a National Transportation Safety Board probable cause report released Thursday.

Investigators with the NTSB said that Cessna 150 pilot Robert Lilly was dealing with an extreme low fuel state when he was instructed to go around by the air traffic control tower. Lilly, who did not communicate his situation to the controller, was killed in a subsequent crash at the field along with his passenger, Jessi Nelson.

The report said the accident was due to "A loss of engine power due to fuel starvation as a result of a low fuel state and a nose-high attitude during a go-around, which unported the fuel tank feed line, and the pilot's decision to make a low-altitude turn back to the airport, which resulted in an aerodynamic stall and loss of control."

According to the report, after departing Wasilla 20 minutes earlier, Lilly was on final approach for runway 25 following behind a Cessna 172. After the 172 landed, the tower directed Lilly to go around in order to provide the other aircraft with additional time needed to clear the runway. Lilly did not respond to this instruction, nor did he answer two subsequent requests or communicate his low fuel situation to the tower.

Witnesses told the NTSB they observed the Cessna 150 fly down the runway in a nose high attitude then, over the departure end, they heard the engine lose power, followed by a steep left turn back toward the airport. The aircraft nose then pitched down suddenly and the aircraft hit the ground in a nose-down attitude.

In analysis of the wreckage, investigators found 1.8 gallons of fuel in the right tank and one quart in the left. (The aircraft is designed to feed fuel from both tanks simultaneously, so investigators determined fuel levels were likely equal; fuel would have drained from the left tank through a vent line after the crash, resulting in the lower level on the left side at the crash site.) The Cessna 150 was equipped with long range tanks that each hold 1.5 gallons of unusable fuel. Both tanks were intact and not breached.

No mechanical anomalies were found in post-crash analysis of the engine. Combined with the low fuel levels, the report states it is likely that as the aircraft entered the nose-high attitude while attempting to climb and execute the go-around, fuel couldn't be drawn from the tanks. This resulted in fuel starvation and loss of engine power. As the pilot initiated the turn, the combination of high angle of attack and low airspeed led to aerodynamic stall and subsequent crash.

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Loss of control at low altitude, which is nearly always unrecoverable, is a recurrent cause of accidents in Alaska. As so many safety reports attest, retaining control sometimes means that landing the aircraft in an other-than-runway location is the best choice, while a turn to reenter the traffic pattern is rarely possible.

Two months ago, the pilot of a de Havilland Beaver found himself in a dangerous low altitude situation while departing Lake Hood when the aircraft suffered a total loss of engine power. After an unsuccessful attempt to restart the engine, the pilot chose to fly the aircraft down to the ground, landing in the trees. The pilot and three passengers suffered only one minor injury.

"Pilots should always be ready for engine failure on takeoff," said NTSB Alaska Region Chief Clint Johnson in a recent phone call, "and turning back to the airport is not an option in most cases."

Contact Colleen Mondor at colleen@alaskadispatch.com.

Colleen Mondor

Colleen Mondor is the author of "The Map of My Dead Pilots: The Dangerous Game of Flying in Alaska." Find her at chasingray.com or on Twitter @chasingray.

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