FA20, vicinity Kish Island Iran, 2014
FA20, vicinity Kish Island Iran, 2014
On 3 March 2014, a Dassault Falcon 20 engaged in navigation aid calibration for the Regulator was flown into the sea near Kish Island in dark night conditions. The Investigation concluded that the available evidence indicated that the aircraft had been inadvertently flown into the sea as the consequence of the crew experiencing somatogravic illusion. It was also noted that the absence of a functioning radio altimeter and pilot fatigue attributable to the long duty period was likely to have exacerbated the pilots' vulnerability to this illusion.
On 3 March 2014, a Dassault Falcon 20 (EP-FIC) being operated by Aseman Airlines on navigation aids calibration detail at Kish Island for the State Civil Aviation Organisation failed, in night VMC, to complete an eighth flight. It was subsequently found to have crashed into the sea at speed and been destroyed with all four occupants being killed as a result.
An Investigation was carried out by the Aircraft Accident Investigation Department of the Iran Civil Aviation Organisation (CAO). The aircraft was not fitted with a CVR or a FDR and under ICAO Annex 6 was not required to be. Almost all of the aircraft wreckage was recovered and reconstructed in plain view to enable the Investigation to proceed.
It was established that the aircraft had earlier the same day been flown from Tehran Mehrabad to Kish Island by the same flight crew with a third pilot, four ground technicians and "security guard" on board. The Captain and First Officer had "begun their day’s duty at the CAO Offices on preparatory work for the task assigned before proceeding to their aircraft”. The aircraft had then spent an hour on the ground during which time it was refuelled before commencing the inspection / calibration task with just the third pilot and the “security guard” remaining on board with the operating crew. It took off from runway 27R and was cleared to join right hand downwind at up to 1,000 feet and up to 8 miles from the airport. After seven similar and uneventful circuits for Navigation Aid inspection purposes, just as the turn onto final approach was being made for the eighth time, the aircraft had descended into the sea. An examination of the recovered wreckage strongly suggested that impact with the sea surface had occurred with the aircraft under control. It was also found that the aircraft had not been configured for landing at impact and that "the hydraulic actuators of the elevator show no attempts by the pilots to avoid water impact". There was also no evidence which would indicate malfunction of either of the engines or their related components.
It was found that the crew had identified a malfunction of the radio altimeter "while departing from Tehran" and that there was no record of any maintenance action at Kish Island and the circuits there were being conducted in VMC. However, these circuits had begun in daylight but had continued into the hours of darkness. The final circuit involved an approach to runway 27R in order to check the PAPI and the crash location was identified as about to turn onto this final approach. It was considered that the crew would have been vulnerable to a somatogravic illusion which "could have triggered pilot disorientation if the crew were suffering fatigue after beginning their duty period in the office that morning". In the absence of a functioning radio altimeter, the crew would not have been aware of their low height over water due to spatial disorientation.
The Investigation concluded that the Main Cause of the Accident was that the fatigue of the pilots led to them being unable to adapt themselves to the prevailing flight conditions and their spatial disorientation (illusion) prevented them from avoiding a crash into the sea.
Three Contributory Factors were also identified as follows:
- The malfunction of the aircraft radio altimeter.
- Flight crew fatigue.
- The lack of enough supervision of flight calibration operations.
Two Safety Recommendations were issued as follows:
- that the Iran Civil Aviation Organisation should separate the operation of calibration flights for airport navigation aid systems from itself.
- that the Iran Civil Aviation Organisation should establish an oversight group for calibration flights of airport navigation aid systems to ensure the safety of flight operations at airports.
The Final Report was published on 20 December 2016.