What happened
During a Part 91 positioning flight, the copilot was acting as flying pilot. The aircraft performed an intersection departure using 6,300 feet of usable runway. Prior to takeoff, the pilot in command had to instruct the copilot on how to release the parking brake.
During the takeoff roll on runway 31, with a 4-knot wind from 240 degrees, the pilot in command called "V1" and then "rotate." One second later, the copilot said "whoa," followed by an unidentified squealing sound recorded by the cockpit area microphone. The pilot in command reported that the Boeing 737 turned abruptly 30 degrees to the left, prompting an aborted takeoff. The crew reduced thrust, applied brakes, and engaged both thrust reversers. In an attempt to maintain directional control, the crew applied right rudder and pumped the right brake, but the aircraft departed the left side of the runway approximately 2,000 feet from the departure end. One main landing gear contacted an arresting cable before the aircraft continued onto the grass. There were no fatalities.
The investigation
The investigation examined the anti-skid system, which was functional and active for takeoff. The left main landing gear tire had good tread but exhibited a flat spot following the event. A 2,000-foot skid mark was found to the left of the runway centerline, beginning approximately 1,850 feet from the start of the takeoff roll.
Mechanical examination of the left brake, both brake mixing valves, left and right wheelspeed transducers, power brake valve, control unit, and both parking brake valves showed no evidence of preimpact failure or malfunction that would have caused the left brake to apply.
Findings
- The crew did not verbally complete any of the five relevant checklists—"Before Starting Engines," "Starting Engines," "Before Taxi," "Taxi," or "Before Takeoff"—using the required challenge/response method.
- Approximately 8 seconds passed between the unidentified squealing sound and the copilot's instruction to power off.