India’s Plane Accident Investigation Bureau (AAIB) has launched its preliminary report on the Air India flight AI171 crash, pointing to a cockpit gas swap error and elevating questions on pilot actions.
The London-bound Boeing 787-8 Dreamliner skilled a deadly lack of thrust simply seconds into flight, with investigators now specializing in the sudden motion of cockpit gas switches and the following lack of engine energy.
Gas Cutoff Error Below Scrutiny
On the coronary heart of the investigation is a sudden transition of each engine gas management switches from “RUN” to “CUTOFF” shortly after takeoff. In response to flight recorder knowledge, this occurred because the plane reached its most recorded velocity of 180 knots at 08:08:42 UTC.
“The plane achieved the utmost recorded airspeed of 180 Knots IAS at about 08:08:42 UTC and instantly thereafter, the Engine 1 and Engine 2 gas cutoff switches transitioned from RUN to CUTOFF place one after one other with a time hole of 01 sec,” states the AAIB report.
This motion, sometimes reserved for floor procedures, abruptly shut down gas provide to each engines, inflicting them to lose thrust throughout a important part of flight.
The cockpit voice recorder captured a quick, startling change between the 2 pilots.
“One of many pilots is heard asking the opposite why did he cutoff. The opposite pilot responded that he didn’t accomplish that.”
Nevertheless, the report doesn’t make clear which pilot moved the switches or whether or not it was unintended or unintentional. In the course of the takeoff, the co-pilot was flying the plane whereas the captain was within the monitoring function.
Failed Engine Restoration
Moments after the gas cutoff, the pilots reversed the swap positions, trying to revive engine performance. The Boeing 787’s Full Authority Digital Engine Management (FADEC) system robotically started the ignition and gas introduction sequence.
“When gas management switches are moved from CUTOFF to RUN whereas the plane is inflight, every engine’s full authority twin engine management robotically manages a relight and thrust restoration sequence,” the report explains.
Nevertheless, solely one of many engines confirmed partial indicators of restoration.
“Engine 1’s core deceleration stopped, reversed and began to progress to restoration,” whereas “Engine 2 was capable of relight however couldn’t arrest core velocity deceleration,” the report mentioned.
Regardless of these efforts, it was too late. The airplane had already begun to lose altitude, crossing the airport perimeter wall earlier than slamming into the close by BJ Medical School and Hospital hostel advanced, killing dozens of individuals on the bottom.
Emergency Response and Last Moments
Seconds after the gas switches have been toggled again to RUN, the cockpit recorder captured the ultimate misery name.
“MAYDAY MAYDAY MAYDAY,” one of many pilots shouted.
ATC tried to contact the plane’s callsign however obtained no response. The air visitors controller reportedly watched helplessly because the plane crashed within the distance.
Airport CCTV footage confirmed that the Ram Air Turbine (RAT), an emergency backup energy supply, was deployed in the course of the plane’s temporary preliminary climb. Nevertheless, this measure was not adequate to stabilize or keep away from the crash.
Wreckage and Chook Strike Concept Dismissed
Within the aftermath, AAIB investigators secured and examined the wreckage. Each engines have been retrieved and quarantined for additional evaluation. Parts deemed vital have been additionally remoted for detailed inspection.
“Wreckage website actions together with drone pictures and videography have been accomplished,” the report confirmed.
Crucially, the preliminary report addressed hypothesis {that a} hen strike might have prompted the crash. Nevertheless, surveillance footage and radar knowledge present no indicators of hen exercise alongside the flight path.
“No vital hen exercise is noticed within the neighborhood of the flight path,” the report famous.
This successfully guidelines out hen strike as a contributing issue.
Pilots’ Expertise and Background
The captain of flight AI171 was a 56-year-old veteran with greater than 15,000 flying hours, whereas the co-pilot was a 32-year-old with 3,400 hours. The First Officer was the pilot flying (PF) throughout takeoff, whereas the captain served in a supervisory capability.
The report doesn’t but draw conclusions about potential pilot error however highlights the deal with the sudden gas swap motion.
No Plane or Engine Fault Recognized
Considerably, the AAIB has discovered no quick technical fault with the Boeing 787-8 plane or its GE GEnx-1B engines.
“At this stage of investigation, there are not any advisable actions to B787-8 and/or GE GEnx-1B engine operators and producers,” the report said, suggesting that mechanical or programs failure is just not at the moment suspected.
The preliminary report factors towards human components and cockpit administration as possible central points within the tragedy. The AAIB continues to research the gas cutoff occasion, the following engine relight makes an attempt, and the decision-making dynamics between the flight crew.
