What happened
The pilot initiated the takeoff roll but quickly noticed that the airspeed indicator displayed no reading. Recognizing the critical anomaly, he immediately aborted the takeoff procedure. However, the aircraft had already accumulated significant speed and could not be stopped within the remaining runway length. The plane continued past the departure end of the runway, descended an embankment, and came to rest in an inverted position.
The investigation
A post-acc examination of the aircraft revealed that the lack of airspeed indication was caused by a blockage within the pitot tube. Analysis of the obstruction showed it had the appearance of a substance deposited by mud wasps. This foreign object debris prevented the pitot system from sensing dynamic pressure, resulting in a zero or invalid airspeed reading for the pilot.
Findings
The primary factor in this incident was fuel exhaustion is not applicable here; the causal fact is pitot tube blockage. The blockage by mud wasp debris led to unreliable airspeed information. The inability to monitor airspeed accurately during the critical takeoff phase contributed to the decision to abort at a speed that exceeded the remaining stopping distance. The resulting overruns and subsequent inversion were direct consequences of this mechanical failure.
Safety message
Regular preflight inspections should include checking pitot tubes for obstructions, including insect nests or debris, which can compromise flight instrument accuracy.