Pilot error along with mechanical fault has caused the fatal accident involving a Gulfstream G-IV business jet in May 2014 at Bedford, ...
Pilot error along with mechanical fault has caused the fatal accident involving a Gulfstream G-IV business jet in May 2014 at Bedford, Massachusetts, according to NTSB investigation.
The G-IV airplane was destroyed after a rejected takeoff and runway excursion at Laurence G. Hanscom Field in Bedford, killing all the seven onboard, including the 2 pilots, a flight attendant and four passengers.
Specifically, the pilots failed to perform a flight control check before takeoff then attempted to take off while critical flight controls were locked because a gust lock was engaged. Finally, they delayed rejecting the take-off after they became aware the flight controls were locked.
Due to pilot error, the gust lock, which is used to lock the control surfaces at ground was not dis engaged before the take off roll. As a result the airplane was unable to become airborne when it reached its take off speed, due to the locked control surfaces.
Pilots effort to disengage the gust lock by shutting down the flight power shut off valve proved ineffective.
The faulty gust lock safety feature did not limit the throttle movement sufficiently to prevent an unsafe take off, enabling the aircraft to reach its take off speed. It allowed 3 to 4 times throttle lever movement than design intent.
The aircraft collided with runway lights and localiser antennae, before coming to rest in a ravine formed by shashene river, and was completely destroyed in the post crash fire.
The flight data recorder and cockpit voice recorder indicated that neither of the two flight crewmembers, who had flown together for about 12 years, had performed a basic flight control check that would have alerted them to the locked flight controls. A review of the flight crew’s previous 175 flights revealed that the pilots had performed complete preflight control checks on only two of them. The flight crew’s habitual noncompliance with checklists was a contributing factor to the accident.
“This investigation raises troubling questions about how a long-term pattern of noncompliance was allowed to develop for this very experienced flight crew,” Dinh-Zarr said. “More importantly, our investigation asks whether this is a prevalent practice in the business aviation community, and how we can prevent these accidents from happening again.”
About 26 seconds into the takeoff roll, when the airplane had reached a speed of 148 mph (129 kts), the pilot in command indicated that the flight controls were locked, but the crew did not begin to apply the brakes for another 10 seconds and did not reduce engine power until four more seconds had passed. The NTSB determined that if the crew had rejected the takeoff within 11 seconds of the pilot’s comment, the airplane would have stopped on the paved surface and the accident would have been avoided.
The G-IV gust lock system design was intended to limit the operation of the throttles when the system was engaged so that the flight crew would have an unmistakable warning that the gust lock was on should the crew attempt to take off. However, the investigation revealed that Gulfstream did not ensure that the gust lock system would sufficiently limit the throttle movement on the G-IV airplane, which allowed the pilots of the accident flight to accelerate the airplane to takeoff speed before they discovered that the flight controls were locked.
The NTSB said that the Federal Aviation Administration’s certification of the gust lock system was inadequate because it did not require Gulfstream to perform any engineering certification tests or analysis of the G-IV gust lock system to verify that the system had met its regulatory requirements.
Also contributing to the accident were Gulfstream’s failure to ensure that the gust lock system would prevent an attempted takeoff with the gust lock engaged and the FAA’s failure to detect this inadequacy during the G-IV’s certification.
As a result of the investigation, the NTSB issued a total of five safety recommendations to the FAA, the International Business Aviation Council and the National Business Aviation Association.
In addition, the NTSB developed a Safety Alert for all pilots on the importance of following standard operating procedures and using checklists to guard against procedural errors.
