It could take months to reach definitive conclusions explaining India’s deadliest plane crash in three decades.
But a New York Times analysis of photos and videos from the June 12 incident — which were reviewed with aviation safety experts, including former pilots and crash investigators, as well as an audio forensics expert — reveals key details about the disaster.
The analysis suggests that the plane likely extended its wing flaps and slats before takeoff, used adequate runway distance, and took off from a typical point with a relatively normal initial ascent.
Within seconds of takeoff, however, the landing gear retraction process appears to have failed, and the plane’s emergency power generator was likely deployed.
Experts say these failures indicate that the plane could have experienced a catastrophic loss of hydraulic, electrical or engine power while airborne.
A takeoff like any other
The takeoff of Air India Flight 171 from the Ahmedabad airport has been under intense scrutiny for early warning signs that would suggest that issues appeared before takeoff. However, multiple experts interviewed by The Times said that the initial takeoff appeared relatively normal and that it did not seem as though the plane lacked necessary thrust from its engines on the ground.
A New York Times analysis of CCTV footage and flight data shows that the position where the plane left the runway was in line with its seven previous departures from the same runway. The Times determined the likely position of the CCTV camera and used its perspective to determine the plane’s approximate takeoff point.
Flight used the usual runway length
Gaps in available flight tracking data have raised another question: whether the aircraft used the back half of the runway, which would normally be necessary to generate enough power for takeoff.
At about 1:34 p.m. local time, the aircraft was taxiing adjacent to the departure runway but had not entered it, flight tracking data shows. Five minutes later, around 1:39 p.m., data shows the plane airborne near the end of the runway, with no recorded points in between.
A Times analysis of the CCTV footage shows that the aircraft’s position on the runway when it enters the video frame at 1:38 p.m. would only be possible if it had backtracked on the runway.
The fatal flight’s initial trajectory in the air is also somewhat typical and does not deviate significantly from the previous seven Air India Flight 171 departures from Ahmedabad, according to historical flight data.
“Once the airplane gets airborne, the initial climb rate looks pretty normal,” said John Cox, a former airline pilot.
Slats and flaps were likely extended
The airplane’s rapid descent shortly after taking off has raised concerns about whether the slats and flaps on its wings were in an extended position for takeoff. They are typically deployed before takeoff to provide more surface area to create lift.
A photo from the wreckage site shows the right wing slats in an extended position, suggesting they were likely extended for takeoff.
Soot and burn marks visible on the wing also suggest that when the aircraft crashed, the slats were in an extended position.
The burn marks indicate that the slats were deployed prior to impact, or at least when the explosion occurred on the ground, said Shawn Pruchnicki, a former accident investigator at the Air Line Pilots Association.
The extended position of the slats also indicates that the flaps on the trailing edge of the wings were deployed, despite a lack of clear visibility of the flaps in the crash video, according to Mr. Pruchnicki. All Boeing 787-8 aircraft, like Air India Flight 171, automatically extend their slats when the flaps are activated by pilots.
Another indication that the slats were extended during flight comes from a video of the crash shot from a nearby rooftop, which shows a slight shadow on the leading edge of the plane’s right wing as it descends.
While some experts have noted that it may be too difficult to say with certainty that the slats were extended based on the video quality, it is further evidence that they likely were — suggesting that pilots carried out some standard procedures at the beginning of the flight.
Landing gear failed to fully retract
Analysis of the same video reveals one of the earliest signs of trouble after takeoff: failure to fully retract the plane’s landing gear back into the aircraft’s fuselage.
Soon after takeoff, pilots usually retract the landing gear, which is in a default front-wheel-up position immediately after takeoff.
Typical landing gear after takeoff
While planes can technically fly with their landing gear extended, pilots typically retract it to reduce drag.
In the crash video shot from the rooftop, the landing gear truck is visibly in a front-wheel-down position after liftoff.
Air India’s 171’s landing gear after takeoff
The tilted position indicates that the landing gear retraction sequence was initiated in the cockpit as it would have been on any other takeoff, but the retraction appeared to have failed in the middle of the process.
The landing gear must be positioned correctly in order to fit back into the airplane’s fuselage, said John Goglia, a former member of the National Transportation Safety Board.
It appears that the pilots activated the landing gear retraction sequence from the cockpit, but that they were not able to fully retract the gear, possibly because of issues such as an electrical failure that caused a loss of hydraulic power, Mr. Goglia said.
Emergency power generator was activated
If a plane like the Boeing 787-8 Dreamliner suffers from an abrupt loss of electrical, hydraulic or engine power at any altitude, an alternative power source is automatically deployed from the bottom of the jets. Known as the ram air turbine, it can also be manually activated.
The turbine does not generate enough electricity to power all functions on an aircraft, but it might provide sufficient power to help land a plane in an emergency situation.
Multiple aviation experts The Times spoke with pointed to the distinct sound audible in the video shot from a nearby rooftop as evidence for likely deployment of the flight’s emergency power generator.
To further verify this, The Times worked with Cesar Lamschtein, a media forensics expert who specializes in audio analysis, to compare the audio signature of the fatal flight with another example of a Dreamliner jet landing with the turbine deployed.
The analysis showed that the sound from the fatal flight was over 97 percent consistent with a different instance of emergency turbine deployment.
How Air India 171 sounded during its descent
Aircraft showed no visible swerve
There are additional indications that the plane may have experienced a loss of engine power after takeoff.
Generally when planes lose a single engine, they swerve slightly to one side before the pilot or the aircraft’s computer system corrects the issue. However, that is not visible in either available video of the crash.
“You don’t see any kind of indication of asymmetric thrust. You don’t see yawing, you don’t see rudder deflection, you don’t see smoke, or puffs of flame from either engine,” said Jeff Guzzetti, a former accident investigator for the Federal Aviation Administration. “That all adds up to me to be a symmetrical loss of power.”
This suggests that the issues that may have caused both the engines to fail likely occurred at nearly the same moment— a highly unusual scenario, experts said.
Possible explanations of a simultaneous dual engine failure could include contamination of the fuel source into both engines, or an issue stemming from an incorrect input of flight parameters before takeoff.
Investigators will be assessing these possibilities and more as they uncover additional details from the plane’s black boxes in the coming days and weeks.