Runway Overrun When the Takeoff Is Aborted

Because people are fallible by nature, it makes sense that personnel activities were to blame for around 80% of aircraft accidents and incidents. By bridging the gap between the practical application of procedures and human operator, the Human Factor Analysis and Classification System (HFACS) enables the most effective analysis of accidents and the avoidance of future errors. The National Transportation Safety Board (NTSB) named a list of mistakes and violations which caused the accident after investigating the crash of G-IV N121JM registered to SK Travel LLC: pilots' failure to perform the flight control check before takeoff, attempt to takeoff with engaged gust lock system, and delayed rejected takeoff procedure (NTSB Aircraft Accident Report 2015). Also, investigators determined a couple of preconditions, such as broken lock pin in the gust lock handle and sunglasses jammed inside the pedestal which played a vital role in the tragic scenario. NTSB, Federal Aviation Administration (FAA) and International Business Aviation Council (IBAC) issued appropriate recommendations concerning the aircraft certification, procedures of compliance with checklists and Control System Gust Locks amendment.

Key words: crash, gust lock system, overrun, human factor.

Runway Overrun During Rejected Takeoff

The first level of Human Factors Analysis and Classification System are unsafe acts which are divided into errors and violations. There are 5 main errors and violations committed by the crew which contributed to the crash:

1. While performing engine start up the pilots failed to disengage the gust lock system, which locks the ailerons, elevators and rudder protecting them from wind gusts, moreover limiting the throttle lever angle (Gulfstream GIV Cockpit Card, 2000). This mistake shouldn’t be fatal as other safeguards should have eliminated the threat.

2. The flight control check was omitted by the crew which could have removed the previous mistake. NTSB discovered that the pilots failed to complete the checklists 98% of their previous flights (NTSB Aircraft Accident Report, 2015).

3. The pilots disregarded the “Rudder limit” message which indicated the overloading on rudder actuator due to the action of gust lock system. This indication was the last opportunity to notice the deviation and take actions before takeoff procedure commencement (NTSB Aircraft Accident Report, 2015).

4. Pilot-in-command engaged to auto throttle despite the discernible limitation in throttle lever movement. The reason of restriction was unclear to the pilot and he tried to push the lever forward with the help of auto throttle and applying manual force thus breaking the lock pin in gust lock handle. Malfunctioning interlock mechanism confused the crew giving the possibility to gain target engine pressure ratio and certainty that takeoff could be continued (Gulfstream Aerospace Corporation Party Submission, 2015).

5. Late takeoff rejection procedure was the last error that contributed to the crash. After the crew discovered that yoke is immobilized they delayed with the takeoff rejection procedure activating the flight power shutoff valve and only after the 11 seconds after “rotate call” flight data recorder recorded brakes application.

The second level of HFACS describes existing preconditions which contributed to the crash. The foreign object testing revealed a pair of sunglasses inside the pedestal near the aft side of the sector assembly sheaves which could potentially have limited the gust lock handle movement. The other precondition was the broken interlock pin influencing throttle lever restriction level. Minimum of engine power should be attained in case the gust lock is engaged, but the system was malfunctioning allowing to deviate the throttles up to 26 degrees.

The third level refers to unsafe supervision by SK Travel who is responsible for the training, risk management and crew pairing. Insufficient level of communication and coordination between pilots was evident after listening of the cabin voice recorder. The company should have noticed that fact and took it into account while pairing the crews. Lack of interaction between pilots delayed the decision about rejected takeoff. Execution of normal checklists is also a part of pilot’s training and should have been provided by SK Travel to ensure an appropriate level of safety.

Organizational influences include the certification of gust lock system to comply with 14 Code of Federal Regulations 25.679. The gust lock system on the crashed G-IV didn’t meet the requirements of 14 Code as it didn’t limit the operation of the throttle levers to the safe level and provided non-sufficient warning at the takeoff stage (Gulfstream Aerospace Corporation Party Submission, 2015)

Conclusion

The results of the analysis show that the crash of G-IV N121JM happened in the result of couple mistakes by the crew, their noncompliance with standard procedures, certification and staff training deficiencies. Negligence from the crew who failed to complete the checklist and lack of control and training from the SK Travel’s side are interconnected. Gulfstream Aerospace Corporation who produced interlock pin for gust lock system used the materials which are not solid enough to withstand the loads they are exposed to during aircraft operation, as solid interlock pin could have limited the throttle lever angle preventing the crash. As the certification for the compliance of G-IV with 14 CFR 25.679 was completed on the engineering drawings only and no engineering certification tests, inspection, or analysis were performed, a lot of deficiencies were omitted.

References

Gulfstream Aerospace Corporation Party Submission, Accident Involving Arizin Ventures LLC - SKC Travel LLC - Operated Aircraft N121JM, May 31, 2014, Laurence G. Hanscom Field, Bedford, Massachusetts, ERA14MA271, May 11, 2015

Gulfstream GIV Cockpit Card, 22 Dec 2000

NTSB Aircraft Accident Report, AAR-15/03, Runway Overrun During Rejected Takeoff Gulfstream Aerospace Corporation GIV, N121JM, Bedford, Massachusetts, May 31, 2014, 2015