Accident Sequence
On May 5, 2021, about 1033 eastern daylight time, an Israel Aerospace Industries Gulfstream G150, registration N22ST, was substantially damaged when it overran the runway at Ridgeland-Claude Dean Airport (3J1), Ridgeland, South Carolina. The two pilots and three passengers were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 executive/corporate flight.
According to the pilot-in-command (PIC), a routine preflight was completed earlier that morning. The crew flew from Fort Lauderdale International Airport (FLL) to New Smyrna Beach Municipal Airport (EVB), then continued to 3J1 with passengers. During the flight, cockpit voice recorder (CVR) data revealed discussions about wind favoring runway 36 and efforts to shorten flight time. At one point, the PIC stated, “they’ll [the other aircraft] slow to 250 [knots] below 10 [thousand feet] and we won’t. We know what we’re doing right now we’re trying to win a race.” The SIC responded, “that’s right,” and the PIC added, “this is NASCAR,” followed by laughter.
During descent, the overspeed warning tone sounded multiple times starting at 1025:30. At 1028:31, the crew was cleared to 2,000 ft and requested a straight-in approach to runway 36. At 1031:35, the autopilot was disconnected. On final approach at about 900 ft above ground level (agl) and 1.5 nautical miles from the threshold, the SIC called out 170 knots (Vref was 121 knots). The PIC responded to add full flaps. The electronic voice announced “sink rate” several times. At 1033:04, the 50-ft callout was made, and the airplane touched down. After touchdown, the PIC called for thrust reversers, then an expletive. The SIC asked about brakes, and the PIC said yes. At 1033:26, sounds of a runway excursion were recorded. The airplane came to rest about 400 ft past the end of runway 36 in marshy, wet terrain.
Witness and Video Evidence
A witness, type-rated on the accident airplane model, observed touchdown near the A4 taxiway (close to the 1,000-ft markers). About 2 seconds after touchdown, he saw both thrust reversers deploy and heard their roar. He later saw the airplane depart the runway. A mobile phone video captured the final approach and landing roll. It showed the right engine thrust reverser deployed shortly after touchdown and the left engine thrust reverser deployed about 11 seconds after touchdown. During the landing roll, neither the ground air brakes nor flight air brakes deployed on either wing. The video also showed the windsock indicating a quartering tailwind, sometimes nearly fully extended (about 15 knots). The pilot-rated witness reported the wind as 220°-230° at 11-13 knots. Another witness described a “strong and gusty” southwesterly wind.
Post-Accident Examination
Postaccident examination revealed that the nose landing gear and right main landing gear (MLG) had partially sheared, and the left MLG remained attached. The right MLG weight-on-wheels and wheel speed sensors were damaged; hydraulic lines to the right MLG were sheared. The flaps were set to 40°, and all air brakes were stowed. In the cockpit, the flight air brake switch was in the retract position, and the ground air brake switch was set to land. Electrical testing of the switches showed normal currents. The left throttle microswitch read normally, but the right throttle microswitch initially read about 600 ohms (higher than normal). When the right throttle was moved slightly, the resistance decreased to normal.
Brake and Thrust Reverser Analysis
Downloaded engine data indicated both engines operated normally and responded to power lever inputs. Both thrust reversers deployed about 2 seconds after touchdown and remained deployed for about 21 seconds. Tire marks showed the airplane touched down about 1,000-1,200 ft down the runway. Most marks were light, except heavy braking marks appeared about 1,000 ft from the runway end and continued off the runway. The PIC stated that upon landing, he applied wheel brakes and thrust reversers, but the ground air brakes did not deploy. He reported, “We did not have brakes, no thrust reversers and no ground air brakes.” The SIC also reported “I have no brakes” during the landing roll.
Landing Distance Calculation
According to Gulfstream Aerospace documentation, if ground air brakes are inoperative, landing distance must be increased by 30%. Using data consistent with the accident flight and a 10-knot tailwind (the manual’s limit), the unfactored landing distance was 3,034 ft. With the 30% increase, the ground roll landing distance became 3,944 ft. The accident airplane touched down about 1,000 ft down the 4,200-ft runway, leaving insufficient distance to stop within the available space.