What Happened
On May 5, 2021, about 10:33 a.m. eastern daylight time, Gulfstream G150 N22ST overran the runway at Ridgeland-Claude Dean Airport, South Carolina. The two pilots and three passengers were uninjured. The aircraft stopped in marshy terrain about 400 feet beyond the runway, with substantial damage to the fuselage and wings.
The crew had completed a positioning flight from Fort Lauderdale to New Smyrna Beach, Florida, picked up the passengers, and continued toward Ridgeland. During the flight, cockpit recordings captured a desire to arrive quickly and ahead of another jet bound for the same airport.
The captain compared the trip with an automobile race. The overspeed warning sounded several times during descent. The flight’s pace had become part of the cockpit discussion well before the airplane reached final approach.
The crew chose a straight-in visual approach. On final, the airplane was high and fast. The second-in-command made airspeed calls and asked about using S-turns, but the captain said those turns were unnecessary. Electronic sink-rate and pull-up warnings sounded repeatedly.
The crew continued. The airplane touched down about 1,000 feet beyond the threshold of a 4,200-foot runway. That left approximately 3,200 feet of pavement for the remaining landing roll, before accounting for the effects of the tailwind and the systems that did or did not deploy.
The captain later said the wheel brakes, thrust reversers, and ground air brakes had not worked. Video and physical evidence showed a more specific picture. The thrust reversers deployed soon after touchdown, and tire marks showed braking through the ground roll. The ground air brakes did not deploy.
Braking marks became heavy over the last 1,500 feet, where the antiskid system activated. The airplane continued beyond the pavement and came to rest in the marsh.
Investigation Findings
The NTSB identified both the continued unstable approach and the failure of the ground air brakes to deploy as causes of the overrun. Keeping both findings in view matters. The investigation did not find that every stopping system had failed, and it did not dismiss the missing air brakes simply because the approach was unstable.
Investigators found no preaccident malfunction in the hydraulic system, wheel brakes, thrust reversers, or weight-on-wheels switches. They also found no electrical issue with the air-brake switches. The automatic ground-air-brake switch was positioned to allow deployment.
The deployment logic required both throttle levers to be below an 18-degree throttle-lever angle. During testing, the right throttle microswitch initially produced abnormal electrical resistance. After the throttle was touched and moved, its resistance tested normally. That intermittent result did not allow investigators to establish whether the switch had prevented deployment during the landing.
Landing calculations showed that without the ground air brakes, the required ground roll exceeded the runway remaining after the touchdown point. Mobile-phone video also indicated a quartering tailwind of about 10 to 15 knots. The airplane’s tailwind landing limit was 10 knots, and the NTSB concluded that the landing exceeded that limitation. The wind further increased the stopping distance beyond the calculated case.
The crew had received repeated indications that the approach was unstable: excess height, excess speed, unusual descent rate, and the recorded warnings. The Board found that either pilot had an opportunity to call for a go-around and that doing so would have been appropriate.
The motivation to arrive quickly, apparently to accommodate the passengers, was a contributing factor. It connected the en route race discussion to the final decision to continue, without requiring a claim that the passengers had explicitly ordered the crew to race.
NTSB Probable Cause
The flight crew’s continuation of an unstable approach and the failure of the ground air brakes to deploy upon touchdown, both of which resulted in the runway overrun. Contributing was the crew’s motivation and response to external pressures to complete the flight as quickly as possible to accommodate passenger wishes and the crew’s decision to land with a quartering tailwind that exceeded the airplane’s limitations.
Safety Lessons
The following takeaways apply the investigation findings to flight planning and cockpit decisions.
- Use approach stability as the decision point. A runway can look reachable while the landing is no longer within a workable performance margin. Apply the go-around criteria appropriate to the aircraft and operation when excess speed, height, or sink rate persists.
- Calculate for the actual wind and touchdown. Runway length is not the same as runway remaining after touchdown. Confirm the actual wind, aircraft limitations, and landing performance rather than carrying an earlier, more favorable assumption onto final.
- Keep speed of service outside the landing decision. An estimated arrival time and another aircraft arrival do not improve stopping performance. Either crewmember needs to be able to end an unstable approach without making the decision a contest.
Watch the Full Analysis
Frequently Asked Questions
Q: Did all of the Gulfstream G150 brakes fail at Ridgeland?
A: No. Evidence showed wheel braking and thrust-reverser deployment. The ground air brakes did not deploy, and investigators could not conclusively determine why.
Q: Was the Gulfstream crew racing another airplane?
A: The cockpit recording showed a desire to arrive ahead of another aircraft, and the captain compared the flight to an automobile race. The NTSB linked external pressure and the wish to complete the flight quickly to the accident.
Q: What caused the Ridgeland runway overrun?
A: The NTSB cited continuation of an unstable approach and failure of the ground air brakes to deploy. A quartering tailwind beyond the aircraft limit and pressure to arrive quickly contributed.
Sources and References
