CESSNA 172 — Ukiah, CA

What happened

The student pilot was making his second solo cross-country flight.

The pilot used an onboard camera to record the ground run, takeoff, and initial cruise segments of the flight and then turned it off. The recordings showed those portions of the flight were uneventful, but he was heard talking to himself about dropping a pen and a pencil.

The pilot turned the camera back on as he approached the destination airport, which was moderately busy with multiple aircraft in the traffic pattern. During the approach, the pilot’s performance of the pre-landing checklist was interrupted due to a close encounter with a bird, and he did not complete the step of checking that his seatbelt was fastened. During the landing flare, the pilot transmitted on the local frequency his intention to perform a go-around. The airplane began to climb and reached about 60 ft above ground level (agl) when a change in the stroboscopic effect of the propeller was recorded, which likely indicated an engine speed change. The airplane leveled off, and the pilot said, “whoa, whoa, whoa,” before the recording ended.

Airport security video footage revealed that after reaching midfield, the airplane pitched down and struck the ground in a nose-low attitude, collapsing the nose gear. Thereafter, the propeller struck the ground, and the airplane continued under power for an additional 700 ft until it nosed over in a grass area and came to rest inverted. Sound spectrum analysis of the security video revealed that the engine was operating throughout the video and continued to operate after impact.

The airplane’s cabin sustained minimal damage during the accident sequence; however, the pilot, who was not restrained by a seat belt, was partially ejected through the windshield and sustained fatal injuries. The pilot was likely incapacitated from the initial impact and therefore unable to reduce engine power after the nose gear collapsed.

During the week before the accident, the airplane was stored outside during heavy rain. Postaccident examination revealed water in the left tank and the gascolator, although both the accident pilot and the pilot who flew the airplane earlier in the day followed the correct procedure for draining contaminants.

Examination of the left fuel tank revealed that a longstanding leak in the left fuel tank filler neck assembly had allowed water into the tank. Pre-accident internal damage and buckling of the tank’s lower skin appeared to have trapped water and prevented it from reaching the drain port. It is likely that this water moved and entered the engine’s fuel supply system as the pilot maneuvered the airplane in the traffic pattern. The change in the stroboscopic effect of the propeller observed shortly after the pilot began the go-around was consistent with a power interruption due to water entering the engine. With sufficient runway remaining, the pilot likely decided to abort the go-around and land.

The airplane manufacturer had issued a service bulletin that recommended the installation of additional drains in the fuel tanks. If installed, these drains may have revealed the water; however, the additional drains had not been installed, nor was this required per Federal Aviation Administration (FAA) regulations.

The engine did not experience a total loss of power at any point during the video-recorded portions of the flight. Examination revealed that the cam lobes of the engine exhibited excessive wear; however, such damage is progressive in nature and typically occurs over an extended period. The wear would have resulted in a gradual reduction in engine performance over that time, rather than an immediate or intermittent power loss.

According to the pilot’s flight instructor and his spouse, the pilot was a strong advocate of seatbelt usage. Although the reason for his failure to wear a seatbelt could not be determined, it is possible that when he dropped his writing implements during the flight, he released his seat belt to recover them and failed to resecure it. When his pre-landing checklist was interrupted due to the proximity of a bird, he became preoccupied by the busy airport environment and did not finish the checklist.

Autopsy results indicated that the pilot had severe coronary artery disease; however, based on available medical and operational evidence, it is unlikely that the heart disease contributed to the accident. Although toxicology samples revealed codeine and morphine in the pilot’s urine, there was no detectable codeine or morphine in his blood, and it is unlikely that effects of those substances contributed to the accident.

An editorial "what led to it / how to avoid it" analysis for this accident is generated separately and will appear here.