Kish Air Flight 7170
A Kish Air Fokker 50 similar to the one involved in the crash.
|Date||10 February 2004|
|Site||Al Muwafjah, Sharjah|
|Fatalities||43 (37 passengers, 6 crew)|
|Aircraft type||Fokker 50|
|Flight origin||Kish Airport, Kish Island, Iran|
|Destination||Sharjah International Airport, Sharjah, United Arab Emirates|
Kish Air Flight 7170 was a scheduled international passenger flight, operated by an Ektaban-based Iranian airlines Kish Air from Kish Island in Iran to Sharjah, United Arab Emirates (UAE). On 10 February 2004, the aircraft serving the route, a Fokker 50, crashed while approaching to land at Sharjah International Airport killing 43 of the 46 occupants. The final report, conducted by Emirates General Civil Aviation Authority, concluded that pilot error was the cause of the accident.
Flight 7170 departed Kish Airport, Kish Island with 40 passengers and a crew of six on board, on a flight to Sharjah International Airport, Sharjah with the Captain initially as the pilot flying (PF). The weather at Sharjah was in good condition as well as the visibility. Whilst on final approach to runway 12 at the airport, the plane suddenly pitched down and rolled. The plane continued to pitch down and rolled. The pilots lost control of the aircraft causing it to crash into an open space within a residential area about 2.6 nautical miles (4.8 km) from the end of the runway. Of the 46 on board, three passengers survived the crash; as of 2013 this is the deadliest crash involving a Fokker 50.
There was a large explosion on impact. The fire immediately engulfed the remains of the cockpit section. The fire spread to the main cabin area, totally destroyed it. The rescue and fire fighting vehicles were not at the scene for almost 25 min after the accident. The access to the site by the rescue and police services was hampered by the number of private vehicles and people crowded into the restricted residential area. The fire was extinguished about 30 minutes after the accident but the wreckage continued to smoulder for a further hour.
There were four survivors initially found in the fuselage section however one died on the way to hospital. A witness, who was on the scene very quickly, stated that the main fuselage was still intact when he arrived and he could hear people inside requesting help. Attempts were made to gain access to these passengers through the front door but it would not move as it appeared to be crushed and fire prevented access to the cabin through open sections of the fuselage. The fire intensified very quickly forcing rescuers away and it quickly engulfed that section of the fuselage. A photograph taken approximately 10 minutes after the accident showed the cabin totally engulfed. There may have been more survivors if immediate access to the cabin had been achievable. The survivors could not remember any details of their seating position although it was most likely that they were seated in the middle section of the main cabin behind the wing.
The aircraft involved was a Fokker 50, registered EP-LCA. It first flew on 25 January 1993 with Lufthansa CityLine as D-AFFJ, then to Air Nostrum for Iberia as EC-GKU prior to being delivered to Kish Air on 1 March 2002. The aircraft had followed an "A" check on 24 December 2003 and was due to another check on 31 April 2004. The aircraft was equipped with two Pratt & Whitney Canada engines and two Dowty Propellers.
The investigation was conducted by Emirates General Civil Aviation Authority, as well as several investigation team from the outside, including the Iran Civil Aviation Organization (CAO) (as the State of Operator/Registry), Dutch Transport Safety Board (as the manufacturer of the aircraft), Canadian Transportation Safety Board (as the engine manufacturer), UK Air Accidents Investigation Branch (as the manufacturer of the propellers) and the US National Transportation Safety Board (as the manufacturer of the aircraft's skid control unit).
Based on the aircraft's logbook, there were no recorded defects or unscheduled maintenance since overhaul. The aircraft technical logbooks indicated that there had been no scheduled or unscheduled maintenance conducted on the aircraft propeller components.
The Cockpit Voice Recorder and the Digital Flight Data Recorder were retrieved from the relatively undamaged tail section of the aircraft in very good condition. They were presented to the Bureau Enquetes Accidents (BEA) in Le Bourget, France on 16 February 2004 for extraction of the DFDR data and CVR transcription.
From the CVR, the Captain is heard to hand over control of the aircraft to the First Officer during the descent to 2500 ft and to tell the First Officer that this will be the First Officer’s flight. The First Officer is not expecting this and he does not accept this willingly as he is not confident of his ability to conduct the VOR/DME approach into Sharjah. The First Officer is heard to say that he doesn’t have the same experience as the Captain to conduct this approach and the Captain insists. The Captain, in an attempt to boost the First Officer’s confidence, is heard to encourage him and continued to assist him during the conduct of the approach. This generates some discussion and the First Officer continues to fly with the Captain giving advice on inbound track capture and approach profile. There is an inconsistency with this exchange as the First Officer had over 4000 flight hours, of which 600 hours were on the F27 Mk.050 aircraft and he had another 2400 hours as pilot in command on large turbo-prop aircraft (Lockheed Hercules C-130).
The CVR indicated that the Captain took over control of the aircraft and intended to hand over control again to the First Officer once the aircraft was on the correct profile for landing. The First Officer discusses the limiting altitudes and DME distances to be observed. On reaching the 4 nm point from the DME the First Officer is heard to disconnect the autopilot and shortly afterwards call for "Flap 10" then "landing gear down". The Captain then states that he has control. A few seconds later the propeller(s) RPM noise is heard increasing.
The FDR parameter for the low propeller pitch lights indicate that the left propeller entered the ground control range about 1 sec prior to the right propeller, yet the propeller RPM parameters indicated that both propellers moved simultaneously into the ground control range. The engine, aircraft and propeller manufacturers were in agreement that propeller behaviour in a ground control range during flight was unpredictable. However, from analysis of the DFDR data, there was a general consensus as to the propeller behaviour.
On selection of the power levers into the ground control range, the propeller pitch changes resulted in decrease of lift over the wing and turbulent low speed airflow over the tail plane and elevator. Coupled with other aerodynamic moments associated with lift/drag and thrust/weight coupling, the aircraft pitched down and remained in a nose low attitude. The aircraft then commenced a roll to the left most likely due to the asymmetric drag effects of the different propeller pitch angles. The left propeller then went to full reverse whilst the right propeller remained in positive pitch within the ground control range.
Investigators stated that there was a general forecast of a weakening high pressure gradient covering the area with no low level instability expected. The actual weather at the time of the accident was fine with bright sunlight, slightly hazy with light and variable winds. Investigators at the scene reported clear skies and light variable winds with conditions as stated in the meteorological reports. Photographs taken from 2 km away and shortly after the accident occurred show the smoke rising almost vertically without wind effect. There were no reports of turbulence prior to the accident and helicopter crews operating into the accident site reporting smooth flying conditions.
Two pilots of another aircraft waiting at the hold point for runway 12 witnessed the crash. The pilots had been told to taxi and hold for Flight 7170 and for that reason were watching the flight land. They told investigators that the aircraft was flying normally when the nose suddenly pitched down to a 60-degree angle and spiraled left. The investigators also learnt from the witnesses that nothing had come off the aircraft beforehand, ruling out structural failure.
The accident was investigated by the General Civil Aviation Authority. The investigation into the crash revealed that the pilots had accidentally selected the propellers to reverse thrust while still in the air. This caused the loss of control and the subsequent crash. The propellers can only move into the ground control range if the power levers are physically moved past the primary stop by a pilot. The also considering several contributing factors:
- By suddenly insisting the First Officer fly the final approach, the pilot in command created an environment, which led to a breakdown of crew resource management processes, the non observance of the operator’s standard operating procedures and a resultant excessive high approach speed.
- An attempt to rectify this excessive high approach speed most likely resulted in the non compliance with the Standard Operating Procedures and the movement of the power levers below flight idle.
- The unmodified version of the Skid Control Unit failed to provide adequate protection at the time of the event.
- Air Caraïbes Flight 1501, a similar crash in Guadeloupe in which the pilots accidentally changed the aircraft's propeller switch into reverse pitch while still in mid-air
- Luxair Flight 9642, a similar crash in Luxembourg in which the pilots accidentally changed the aircraft's propeller switch into reverse pitch while still in mid-air
- Airlines PNG Flight 1600, a similar crash in Papua New Guinea involving a Dash 8 in which the pilots accidentally changed the aircraft's propeller switch into reverse pitch while still in mid-air
- Merpati Nusantara Airlines Flight 6517, a similar crash in Indonesia involving a Xian MA60 in which the pilots accidentally changed the aircraft's propeller switch into reverse pitch while still in mid-air