Date:	Friday 12 October 2018
Time:	01:18
Type:	Boeing 737-8HG (WL)
Owner/operator:	Air India Express
Registration:	VT-AYD
MSN:	36340/3122
Year of manufacture:	2009
Total airframe hrs:	29719 hours
Cycles:	10023 flights
Engine model:	CFMI CFM56-7B27
Fatalities:	Fatalities: 0 / Occupants: 136
Aircraft damage:	Substantial, repaired
Category:	Accident
Location:	Tiruchirappalli-Civil Airport (TRZ) -   India
Phase:	Take off
Nature:	Passenger - Scheduled
Departure airport:	Tiruchirappalli-Civil Airport (TRZ/VOTR)
Destination airport:	Dubai Airport (DXB/OMDB)
Investigating agency:	AAIB India
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
Air India Express flight 611, a Boeing 737-800, impacted the localizer antenna and an airport wall on takeoff from Tiruchirappalli International Airport, India.
The aircraft was operating a regular flight to Dubai. It was cleared for takeoff from runway 27 at 01:18 local time. As the aircraft accelerated through a speed of 117 knots, the captain's seat recliner mechanism failed. As the captain became unsettled, the throttle levers and control column were moved back inadvertently. He handed over control to the co-pilot for five seconds.
After adjusting his seat the captain took control back from the co-pilot and the take off was continued.
Both crew members failed to notice drop in engine thrust from 98% to 77%. And since the Auto Throttle was in Throttle Hold mode above 84 kts, the thrust remained at 77%.
At 144 knots, some 2000 feet short of the runway end, the captain raised the nose of the aircraft for rotation. he noticed a slower rotation rate and that a higher control column force was required than normal. He increased the control column force aft in order to get airborne. This caused a higher rotation rate and a pitch angle of 10.7 degrees which lead to tail strike on the undulated soft surface past the end of the runway for 17 meters followed by the aft fuselage contacting the localizer antenna and boundary wall. Both main landing gears also impacted the brick boundary wall, causing two holes.
The aircraft climbed to FL360 and proceeded towards Dubai because all systems were normal. While en route the operations department insisted upon a diversion to Mumbai. At that time the flight was well over the Arabian Sea. The aircraft landed safely at Mumbai at 05:38 local time.

PROBABLE CAUSE OF THE ACCIDENT: Delayed take-off due to reduction of take-off thrust N1 from 98 % to 77 % before reaching V1, inability of both the crew members to monitor the thrust parameters and to take timely corrective action. This resulted in tail strike and subsequent hitting of the localizer Antenna and boundary wall of the airport.
Contributory factors:
- PIC seatback recliner mechanism failure during take-off roll.
- Breakdown of Crew coordination during switching between PF, PM and back.
- Loss of situational awareness

19:30 UTC / 01:00 local time:
VOTR 111930Z 00000KT 5000 BR FEW018 SCT100 27/24 Q1008 NOSIG

20:00 UTC / 01:30 local time:
VOTR 112000Z 00000KT 5000 BR FEW018 SCT100 27/24 Q1007 NOSIG

photo (c) Google Earth, Flightradar24; Tiruchirappalli-Civil Airport (TRZ); 12 October 2018

photo (c) Flightradar24; Tiruchirappalli-Civil Airport (TRZ); 12 October 2018

photo (c) Konstantin von Wedelstaedt; Dubai Airport (DXB/OMDB); 11 March 2011

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