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ASN Wikibase Occurrence # 195014
Last updated: 28 May 2017
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Date:24-SEP-2015
Time:02:39
Type:Silhouette image of generic B734 model; specific model in this crash may look slightly different
Boeing 737-4Q8
Owner/operator:Shaheen Air
Registration: AP-BJR
C/n / msn: 25164/2447
Fatalities:Fatalities: 0 / Occupants: 156
Other fatalities:0
Airplane damage: None
Category:Serious incident
Location:Sharjah Airport (SHJ/OMSJ) -   United Arab Emirates
Phase: Take off
Nature:International Scheduled Passenger
Departure airport:Sharjah Airport (SHJ/OMSJ)
Destination airport:Peshawar-Bacha Khan International Airport (PEW/OPPS)
Investigating agency: General Civil Aviation Authority (GCAA) - United Arab Emirates
Narrative:
Shaheen Air flight number SAI791, operated by a Boeing 737-400 aircraft, departed from Sharjah International Airport in the United Arab Emirates, at 02:39 local time to Bacha Khan International Airport, Pakistan. Instead of the assigned runway 30, the aircraft took off from the parallel taxiway Bravo.
There were 156 persons onboard the aircraft consisting of two flight crewmembers, one observer pilot, five cabin crewmembers, and 148 passengers. The commander was the pilot flying, and the copilot was the pilot monitoring.
For the night departure of the incident flight, the visibility was normal, and the air traffic was light as there was one arrival and no other immediate departures.
During the departure, the air traffic controller was performing the combined functions of ground and tower monitoring and communication. In addition, there was an ATC supervisor on duty in the control tower.
Clearance for taxi and full length runway after pushback and engine start was requested at 02:33 by the copilot. The air traffic controller, via Ground frequency, gave clearance to taxi to Alpha, Alpha two zero, holding point Bravo two zero, runway three zero.
Read back by the Copilot was "Alpha to holding point runway three zero".
The aircraft commenced taxiing at 02:34 and approximately 58 seconds later, the aircraft entered taxiway Alpha on a heading of 121 degrees. At 02:37, with the aircraft continuing on taxiway Alpha at an average ground speed of 10 knots, the air traffic controller instructed the crew to change to the Tower radio frequency. After changing to Tower radio frequency, at 02:38 the copilot advised the air traffic controller that they would be holding short of runway three zero. Thirteen seconds later, the air traffic controller instructed the crew to hold short at Bravo two zero to which the copilot replied that they would hold short of "three zero". The aircraft had reached the end of taxiway Alpha after traveling approximately 960 meters and was turning towards taxiway Alpha two zero at an average speed of eight knots.
With the aircraft still in the turn and before reaching taxiway Alpha two zero, the air traffic controller gave the copilot clearance for takeoff with the instruction "Cleared for takeoff runway three zero, Bravo two zero without delay clear takeoff, surface wind is one three zero degrees five knots. Bye bye". The read back by the copilot confirmed runway three zero for takeoff without mention of Bravo two zero. The aircraft was approximately 200 meters from the runway CAT I/II holding and 360 meters from entering the runway. At this stage of taxi, the aircraft was now moving at an average speed of seven knots. As the airport was not equipped with surface movement radar (SMR), the only means available to monitor ground maneuvering of an aircraft was visually, aided by binoculars.
The air traffic controller had noticed that the aircraft speed had slowed as it taxied towards Alpha two zero and communicated to the copilot to keep the speed up until cleared onto the runway.
Shortly after the aircraft had crossed the OFF stop bar at Alpha two zero, the air traffic controller again repeated takeoff clearance by transmitting "...without delay cleared for takeoff runway three zero..." The copilot responded by repeating the takeoff clearance. The time was now 02:39 and the aircraft ground speed was seven knots.
The aircraft started a left turn, following the green lead-on lights, towards the Bravo taxiway and away from taxiway Alpha two zero on a heading of 30 degrees. The aircraft speed during the turn had decreased to an average of four knots.
The air traffic controller was expediting the incident aircraft for take off as there was another aircraft, an Airbus A320, which was on a seven-mile final for runway 30.
At 02:39:28 the aircraft had entered taxiway Bravo and the air traffic controller requested the copilot to expedite the takeoff as there was traffic turning on final approach to land. The copilot informed the air traffic controller that they would expedite.
During this phase of the aircrafts' movement, the air traffic Controller had stated that visual watch of the aircraft was not maintained due to the window frame design in the visual control room of the watch tower which had obscured the air traffic controller's view. The aircraft was approximately 1 km away from the control tower.
Both engine thrust levers were advanced at 02:39:30 and the aircraft speed increased. At 0239:52, both thrust levers were at takeoff thrust as the aircraft passed the intersection of taxiways Bravo with Alpha 18. The aircraft speed had passed 69 knots and was quickly approaching 80 knots.
Initially the air traffic controller thought that the aircraft was on runway 30 during the takeoff roll but then realized that the lights of the aircraft appeared to be on taxiway Bravo and that the aircraft was passing the taxiway Alpha 18 holding point towards Bravo 14. The aircraft speed was approximately 128 knots as it passed the taxiway Bravo 14 intersection.
The on-duty ATC supervisor also witnessed the aircraft on Bravo taxiway. Between the air traffic controller and the supervisor, a decision was made to allow the aircraft to continue the takeoff, as they could not determine how fast the aircraft was moving and there was no threat to the aircraft from vehicles or obstructions on taxiway Bravo.
At 02:40:25, the aircraft was airborne, and at 02:41:15, the copilot informed the air traffic controller that they were switching over to Dubai ATC. The message was acknowledged
by the air traffic controller. There was no discussion between the flight crew and the air traffic controller about the takeoff from the taxiway.
The aircraft continued to its destination for an uneventful landing.


Causes:
The Air Accident Investigation Sector determines that the cause of the Incident was that, most probably, the flight crew did not devote sufficient attention to the taxi route, or taxi route lighting and signage. The flight crew misunderstood the air traffic control instructions and failed to identify that the aircraft had been aligned on a taxiway, instead of on the runway, resulting in a takeoff from the taxiway.

Contributing Factors:
(a) the aircraft Operator standard operating procedures (SOP) did not require verification by the crew that the aircraft is lined up on the correct runway before commencement of takeoff;
(b) the early takeoff clearance given by ATC when the aircraft was approximately 200 meters away from runway 30 holding point;
(c) the urgency of the air traffic Controller for the aircraft to depart;
(d) the red stop bar lights at the CAT II/III holding point for runway 30 was already OFF;
(e) the brighter green lead-on lights for taxiway Bravo were probably mistakenly interpreted as the lead-in lights for the runway
(f) similar numeric descriptors for taxiway and runway designation;
(g) the air traffic Controller lost visual watch on the aircraft for some time and
(h) the possibility that the flight crew assumed that taxiway Bravo was the runway due the width of the taxiway.

Sources:

https://www.gcaa.gov.ae/en/pages/NewsDetails.aspx?NewsID=451

Accident investigation:
cover
investigating agency: General Civil Aviation Authority (GCAA) - United Arab Emirates
status: Final
number: AIFN/0011/2015
released:25 April 2017
duration of investigation: 1 year and 7 months
download report: AIFN/0011/2015

Images:


Revision history:

Date/timeContributorUpdates
25-Apr-2017 06:22 harro Added
25-Apr-2017 06:52 harro Updated [Time, Total fatalities, Destination airport, Narrative, Photo, ]

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