Summary
On 22 February 2016, Air India Limited's Boeing 777-300 ER aircraft, registered VT-ALJ, was involved in a serious incident while taxiing at Chhatrapati Shivaji International Airport (CSIA), Mumbai. The aircraft was operating scheduled passenger flight AI191 from Ahmedabad to Mumbai. There were 319 passengers, 10 cabin crew, and two flight crew on board. No injuries to persons on board or on the ground were reported.
Flight History
The flight departed Ahmedabad at 1856 UTC and landed on Runway 27 at Mumbai at 1940 UTC. After landing, air traffic control (ATC) issued taxi clearance to parking bay K5 via the route: N - Cross Rwy 14 - N1 - Hold short of M6 - M6 - M - M4 - Y1 - Y3 - K5 in the South East Pier. This clearance was not in accordance with the standard operating procedures (SOP) for Code E aircraft. The centreline lighting for Code E operations was not activated, and a "Follow Me" vehicle, as required by SOP, was not provided at the designated point.
Incident Sequence
While taxiing on taxiway Y1, the crew observed a ground marking indicating "MAX SPAN 36 M." Despite the aircraft's wing span being 64.8 meters, they continued taxiing as per the instructions. The right wing of the aircraft struck a high mast lighting pole. The crew felt a shudder but did not realize the aircraft had hit an object. The "Follow Me" vehicle arrived only at taxiway Y3 after hearing radio communications about the parking bay assignment. During post-flight inspection, the crew discovered damage to the right wing leading edge.
Damage
The leading edge of the right wing sustained damage 29 inches from the wing tip, including the slat (part no. 114W5110-6) and leading edge bottom panel (621AFB). The impact caused the high mast lighting pole to bend and tear at its base, resulting in its collapse onto the area between taxiway Y1 and the perimeter road.
Personnel
The pilot-in-command held an Airline Transport Pilot License (ATPL) with endorsements for B777-200/300 ER and had 4,362 hours total flying experience, with 2,166 hours as pilot-in-command on type. The co-pilot also held an ATPL with 4,203 hours total flying experience. Both crew had adequate rest according to flight duty regulations. Neither had previously taxied via the South East Pier or been involved in a serious incident.
Probable Cause
The probable cause of the serious incident was "In-correct Taxi clearance" and "Non- Adherence of SOP for operations in South East Pier."
Contributory Factors
Additional factors identified in the investigation include inadequate and improper pre-flight briefing, and non-compliance with the ground warning sign "MAX SPAN 36 M."