Atrak A320 at Tehran on Aug 13th 2016, rejected takeoff due to runway excursion
Last Update: November 21, 2017 / 17:13:29 GMT/Zulu time
Incident Facts
Date of incident
Aug 13, 2016
Classification
Incident
Cause
Rejected takeoff
Airline
Atrak Air
Flight number
ATR-1943
Departure
Tehran Mehrabad, Iran
Destination
Mashhad, Iran
Aircraft Registration
EP-TTA
Aircraft Type
Airbus A320
ICAO Type Designator
A320
Airport ICAO Code
OIII
The airport was closed (both runways unavailable) for about 2.5 hours until the aircraft was moved off the runway.
On Aug 18th 2016 Iran's CAA reported a full investigation has been opened into the occurrence rated a serious incident. The aircraft encountered a nose wheel steering problem causing directional drift and resulting in a runway excursion during takeoff.
Iran's CAO released their final report concluding the probable cause of the serious incident was:
The IRI CAO Aircraft incident Investigation Board determines that the probable cause of this accident was the pilot failure to set engine power to take off power without initial stabilization on both engine parameters and also timely manner to safely aborting take-off and stop the aircraft after rolling, which resulted in a runway excursion. This failure occurred because the pilots’ lack of attention with the aircraft FCOM.
contributive factors:
- Failure of the airline to provide its pilots with clear and consistent guidance and training regarding company policies and procedures related to engine stabilization before take-off roll and SOP review.
- Lack of cockpit management (CRM) for task sharing and decision making.
The CAO reported the aircraft received damage to both nose wheel assemblies requiring the nose wheel assemblies to be replaced, minor foreign object damage on blades of both engines and damage to one landing light.
The captain (52, ATPL, 10,100 hours total, 250 hours on type) was pilot flying, the first officer (33, CPL, 2,100 hours total, 1,200 hours on type) was pilot monitoring.
The CAO reported that the thrust lever angles immediately before commencing takeoff were 2.81 degrees left and 5.63 degrees right, the left EPR was 1.01 and the right EPR was 1.03. Both thrust levers were pushed symmetrically to the MCT/FLEX detent over 6 seconds, the right hand EPR increased immediately while the left EPR increased at a lower rate, when the left EPR went through 1.03 the right hand EPR had already reached 1.24. The CAO annotated: "This differential between the 2 engines is as expected, due to the initial difference in N2 speeds. The gradient of the spool up is similar between both engines."
Thus when the aircraft accelerated through 4 knots over ground the aircraft began to veer left, the heading changed from 285 to 280 degrees while the aircraft accelerated to 10 knots over ground. The crew rejected takeoff at 15 knots over ground, right rudder was applied causing the aircraft to turn right via nose gear steering (connected to the rudder pedals while the rudder itself was not yet effective). While the engines began to spool down the aircraft still accelerated while continuing to turn right, at 22 knots over ground left rudder was applied, at 26 knots over ground the right hand thrust lever was advanced while the left thrust lever was pulled to idle. The heading reached 307 degrees then began to decrease again (the aircraft began to turn left again). At a heading of 285 degrees the left engine was idle (EPR 1.01) and the right hand engine at EPR 1.22, the thrust lever was reduced to idle, too. Right rudder was applied again, the aircraft however turned left reaching 258 degrees, the aircraft reached a maximm speed of 31 knots over ground, both engines were pulled into reverse to MAX REV notch. The aircraft stopped off the left side of the runway.
Following the stop of the aircraft two thrust applications were made with EPR up to 1.16, however, the aircraft did not move.
The CAO analysed that given their initial EPR, both engines performed exactly according to the model. The CAO wrote: "As engine stabilization was not achieved prior to advancing the throttles to MCT/FLEX, it led to the aircraft to start rolling and veer to the left due to the thrust asymmetry."
The CAO reported that tests by Airbus revealed the actual trajectory of the aircraft was not possible with just engine thrust and rudder use. The CAO thus analysed: "That the actual trajectory is only possible with the use of the NW tiller deflection of the nose-wheel steering is commanded, firstly to the left and then to the right."
The CAO analysed:
The suitable decision which can be made by the Pilot flying is aborting take off and control the aircraft to prevent RWY excursion. In this section of this incident, the pilot decided to use the nose wheel steering tiller and asymmetric thrust power to control directional of the aircraft. This dangerous decision had leaded to increase speed of the aircraft and reduce crew capability to control the aircraft and prevent RWY Excursion.
Related NOTAMs:
A2207/16 - RWY 29L CLSD DUE TO DISABLED ACFT. 13 AUG 19:26 2016 UNTIL 13 AUG 21:00 2016
A1706/16 - RWY 29R BTN TWY A1 AND TWY A3 CLSD DUE TO WIP. 18 JUN 05:47 2016 UNTIL 18 SEP 05:30 2016 ESTIMATED. CREATED: 18 JUN 05:51 2016
A1689/16 - RWY 29R BTN A3 AND A5 CLSD. 14 JUN 07:44 2016 UNTIL 14 SEP 08:30 2016 ESTIMATED. CREATED: 14 JUN 07:48 2016
Metars:
OIII 131900Z 30004KT 9999 FEW040 31/03 Q1014 A2994 NOSIG
OIII 131830Z 06004KT 9999 FEW040 32/02 Q1013 A2993 NOSIG
OIII 131800Z 05004KT 9999 FEW040 33/03 Q1014 A2994 NOSIG
OIII 131750Z 05004KT 9999 FEW040 33/03 Q1014 A2994 NOSIG
OIII 131730Z 06004KT 9999 FEW040 33/02 Q1013 A2994 NOSIG
OIII 131700Z 05004KT 9999 FEW040 33/03 Q1013 A2994 NOSIG
OIII 131650Z 05004KT 9999 FEW040 33/03 Q1013 A2994 NOSIG
OIII 131630Z 03004KT 9999 FEW040 33/01 Q1013 A2993 NOSIG
OIII 131625Z 03004KT 9999 FEW040 33/01 Q1013 A2993 NOSIG
OIII 131600Z 05004KT 9999 FEW040 34/02 Q1013 A2993 NOSIG
OIII 131555Z 05004KT 9999 FEW040 34/02 Q1013 A2993 NOSIG
OIII 131530Z 16004KT 9999 FEW040 36/M03 Q1013 A2992 NOSIG
OIII 131500Z 18006KT 9999 FEW040 37/M03 Q1013 A2992 NOSIG
Incident Facts
Date of incident
Aug 13, 2016
Classification
Incident
Cause
Rejected takeoff
Airline
Atrak Air
Flight number
ATR-1943
Departure
Tehran Mehrabad, Iran
Destination
Mashhad, Iran
Aircraft Registration
EP-TTA
Aircraft Type
Airbus A320
ICAO Type Designator
A320
Airport ICAO Code
OIII
This article is published under license from Avherald.com. © of text by Avherald.com.
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