What happened
During an attempted takeoff, the pilot seated in the right seat experienced a complete failure to receive any airspeed indication from their instrument panel. Despite this loss of data, the pilot monitoring the left side of the cockpit noted that the left airspeed indicator was reading only 45 mph. Recognizing that this speed was significantly below the required performance parameters for a safe departure, the pilot made the decision to abort the takeoff.
The aircraft subsequently veered off the right side of the runway, coming to rest approximately 1700 feet from the initial point of the takeoff roll. The runway in question, designated as Runway 06, has a total length of 4250 feet. Under normal conditions, with the aircraft at a gross weight of 5000 pounds, the planned liftoff speed would have been 80 mph, requiring a total takeoff distance of roughly 1200 feet on a level, dry, paved surface.
The investigation
Investigation into the circumstances surrounding the incident revealed critical discrepancies between the planned performance data and the actual environmental conditions. Standard takeoff calculations assume ideal surface conditions, specifically a level, dry, and paved runway. However, the pilot reported that the runway was covered with four inches of snow.
This condition drastically altered the aircraft's ability to accelerate to the necessary liftoff speed. The presence of deep snow creates substantial drag and reduces tire traction, making it nearly impossible to achieve the required 80 mph within the available runway distance. Furthermore, the failure of the right-seat airspeed indicator removed a critical redundancy from the cockpit, forcing reliance on a single instrument that was already indicating an insufficient speed for flight.
Findings
The primary factor contributing to the incident was the decision to attempt a takeoff under weather conditions that violated established safety guidelines. FAA Advisory Circular 91-6A explicitly states that takeoffs should not be attempted if there is greater than one-half inch of wet snow on the runway surface. The reported four inches of snow exceeded this limit by eight times.
The combination of excessive runway contamination, which prevented acceleration to safe flight speeds, and the partial failure of the airspeed indication system created a situation where the pilot could not safely continue the takeoff. The aircraft's inability to reach the planned 80 mph liftoff speed resulted in the veer-off and the subsequent departure from the prepared surface.
Safety message
Pilots must strictly adhere to FAA guidance regarding runway contamination. Takeoffs should never be attempted on runways with more than one-half inch of wet snow, as performance data for dry surfaces is not applicable to snowy conditions. Additionally, pilots should recognize that partial instrument failures reduce situational awareness and require immediate abort decisions when performance parameters are not met.