AI-171 VT-ANB Requested Pushback and Engine start
Aircraft ready to depart, requested pushback and engine start from bay 34
Pushback Approved
Air traffic control approves aircraft to be pushed back and to prepare for Engine startup
Engine Startup approved
Air Traffic Control approves Engine Startup
Air Traffic Control queried AI-171
ATC Queried if the aircraft would need full length of the runway, Aircraft confirmed that they required the full length of Runway 23
Taxi Clearence requested
Aircraft requested taxi clearance to Runway 23, which was granted by ATC
Aircraft transferred to Tower control from Ground Control
Aircraft radio was transferred to the Control Tower from Ground Control
Aircraft Instructed to line up on Runway 23
Control tower requested Air India aircraft backtrack on runway 23 via Taxiway R4, and to lineup and wait on runway 23
Takeoff Clearance
Flight 171 cleared for departure runway 23.
Takeoff Roll Commenced
Aircraft began takeoff roll on runway 23.
V1 Reached
V1 reached, aircraft now committed to becoming airbourne
Liftoff
Aircraft became airborne after 62-second takeoff roll.
Initial Climb
Normal climb established under light winds and good visibility.
Fuel control switches sequentially moved
Switches where moved from RUN to CUT OFF 1 second apart. Both engines Immediatley begin to shutdown and stop producing thrust, and therefore they lose climb power.
Ram Air Turbine deployed
RAT Seen deployed
Maximum Climb Attitude
ADS-B recorded ~625 ft AMSL peak altitude.
Engine 1 fuel switch moved from CUTOFF to RUN
Engine 1 cut off switch manually moved to RUN
APU Inlet door opening
APU Inlet door, consistant with the APU starting opens.
Engine 2 fuel switch moved from CUTOFF to RUN
Engine 2 cut off switch manually moved to RUN
Flight Instability Begins
Aircraft deviated from expected climb profile.
EGT Temps start to rise
Engine 1 EGT was observed to be rising for both engines indicating deceleration had stopped and the engine was attempting to spool up.
Engine 2 EGT was also rising, and was therefore relit, but the core deceleration could not be stopped.Fuel was repeatably re-introduced to attempt recovery
AI-171 MAYDAY called made
Pilot contacted ATC to report "No Thrust"
Loss of Control
Rapid descent with lateral oscillations observed.
Initial Impact
Tree strike within B. J. Medical College campus. These trees where 293ft before the aircraft hit Building A
Secondary Impact
Tail struck campus mess building causing breakup. Aircraft hit Building A with a nose up altitude of 8 degress, impacting the building with the trailing edge of the wingbox, just aft of the wing root structure.
Aircraft Breakup
Structural disintegration and empennage separation.
Wreckage Spread
Debris field extended ~300 x 120 metres.
Post-Impact Fire
Multiple structures ignited.
CCTV Capture
Airport CCTV recorded abnormal climb and descent.
External Video Evidence
Aircraft observed descending with instability.
Crash Confirmation
Fire and smoke confirmed at impact site.
Emergency Services Dispatched
Fire and rescue services deployed to the crash site immediately following confirmation of impact.
Search and Rescue Operation Initiated
Systematic search and rescue operations commenced for survivors and casualties.
Crash Site Secured
Security perimeter established and access restricted for authorised personnel only.
Initial Wreckage Mapping
Investigation teams began systematic mapping of debris distribution and impact footprint.
Structural Damage Assessment
Preliminary assessment of building damage and aircraft breakup sequence initiated.
Flight Recorder Recovery
Cockpit Voice Recorder (CVR) and Flight Data Recorder (FDR) successfully recovered.
Flight Data Extraction Begins
Initial data extraction and preservation procedures commenced at investigation laboratory.
Engine Examination Initiated
Both engines transferred for detailed metallurgical and mechanical analysis.
Flight Control Systems Analysis
Investigation into control surface integrity and actuator response conducted.
Avionics Systems Review
Examination of navigation, flight control, and onboard computer systems initiated.
Preliminary Investigation Findings Released
Initial findings indicate abnormal flight profile following takeoff and climb phase.