NTSB Points at Airspeed Error in Macon Overrun

 - July 14, 2014, 1:49 PM

The NTSB says the probable cause of a Beechjet 400 overrun accident in September 2012 at Macon, Ga., was the pilot’s failure to maintain proper airspeed on final approach. Two of the three people on board received minor injuries. The aircraft touched down on a wet runway “at a speed 15 to 19 knots above the calculated Vref speed (based on radar data) of 108 knots with inadequate runway remaining to stop,” the final report said. The pilots told investigators they used maximum reverse thrust, brakes and ground spoilers in an attempt to stop the airplane.

In its just published report, the NTSB said contributing to the overrun was the flight crewmembers’ failure to correctly use the appropriate performance chart to calculate the distance required to stop on a contaminated runway, as well as their general lack of proper crew resource management.

Investigation data further revealed the approach was flown with a glideslope approach angle of approximately four degrees instead of the recommended three-degree angle. The pilots reported that the precision approach path indicator lights, which would have provided an approximate three-degree approach, became inoperable shortly before they began their approach. Although the touchdown location could not be accurately determined, given the approximate glideslope and the excessive speed, the airplane likely floated before touching down.

Based on the airplane’s performance charts, with a Vref of 110 knots it would require a 4,800-foot runway in wet conditions. At Vref + 10 knots, the airplane would require 6,100 feet. The runway at Macon is 4,694 feet long.