Ahmedabad plane crash: New evidence points at RAT deployment on Air India AI171 flight after dual engine failure, says expert | Ram Air Turbine System explained

The pilot issued a "MAYDAY" call seconds after takeoff before losing contact with air traffic control at just 672 feet altitude.

The aircraft was under the command of Captain Sumeet Sabharwal, who had 8200 hours of experience, and was being copiloted by First Officer Clive Kundar, with 1100 hours of flying experience.

Air India AI171 crash: Theories around what caused the accident

Aviation experts, pilots and investigators initially considered three primary scenarios —

First, a dual engine failure caused by bird strike or contamination of the jet fuel.

Second, improperly configured flaps of the aircraft during takeoff procedure.

Third, a possible premature flap retraction by the pilots during climb, instead of raising the landing gear.

All these theories were based on the analysis of the two videos of the aircraft, based upon which observations were made that the aircraft's landing gear remained opened throughout the flight and there was no visible sign of engine fire or smoke in the initial video footage.

Air India AI171 crash: Enhanced video reveals critical evidence

However, the original, better high-quality footage from the crash, rather than the widely-circulated recording that went viral on social media and was widely broadcast, has revealed crucial details of the crash.

Apparently, the viral video had been shot by someone who video recorded the footage as it played on the phone that captured the accident — leading to screen glare and background noise — leading to some crucial facts being missed.

In his analysis, Captain Steve explains: "The video that we all saw and every major news network on the planet went with, was a video of a video, and the quality was extremely poor. The original that was presumably taken from an iPhone or some sort of cell phone is much sharper. It's not a terrific video by any means, but it's much sharper than the video of the other video. So what happened was some cameraman was in front of a screen watching the video play, and you can see him at the very end of it. You can actually see his shadow and you can hear people talking in the background, so the audio is not very good and the visual is not very good. The original is going to show us something that's going to change this whole thing."

The original video from the recorder's phone, has revealed previously undetectable details, thereby shifting the focus of the investigation back on engine failure, than human error.

Captain Steve explains that the clearer video footage allows detailed examination of the aircraft's underside during the final moments of the flight, revealing evidence that the aircraft's emergency systems had deployed. The improved audio quality, he says, also captures sounds that were previously masked by background noise. And together they reveal some startling details.

In the video, Captain Steve says, "...Now a lot of people have been talking about the theory that the RAT had deployed." And he goes on to explain exactly what he thinks could have happened.

Air India AI171 crash: What is RAT? Ram Air Turbine System explained

"What's a RAT? It's a Ram Air Turbine. It deploys on many airplanes — and the 787 has it, 777 has it. The RAT is basically just behind the wing on the right side of the airplane. There's a little door that holds it in, and it looks like a little Evinrude motor (propeller that powers motor boats). It's a little, two-bladed prop (propeller), and the purpose of the Ram Air Turbine is to provide electrical and hydraulic pressure for the aircraft in an extreme emergency," he explains.

"On the 787 in particular, there's three things that will deploy the RAT, and it deploys automatically: a massive electrical failure, a massive hydraulic failure, or a dual engine failure. So any one of those three things will cause that RAT to deploy," he adds.

The veteran pilot explains that the Ram Air Turbine is a critical emergency backup system on modern aircraft like the Boeing 787 in question. This two-bladed propeller motor drops below the aircraft's underbody during extreme emergency situations and provides essential electrical power and hydraulic pressure, when the primary systems of the aircraft fail.

It deploys automatically, producing a distinctive high-pitched whining from it propeller spinning at extremely high speeds.

The new video appears to show that the RAT might have deployed — as the small turbine is supposedly visible beneath the Boeing 787-8 Dreamliner aircraft.

Better audio quality reveals that the "characteristic high-pitched sound" that pilots associate with a spinning RAT has also been captured. Captain Steve says this sound would not be have been emitted from a normally-functioning jet-powered aircraft. He believes that this signature sound of the RAT deploying, matches recordings from other documented cases where RAT had deployed in emergency circumstances.

Air India AI171 crash: Sole survivor's testimony corroborates RAT theory

Captain Steve also recalled sole survivor Vishwash Kumar Ramesh's eyewitness testimony, where he recalls hearing a loud bang followed by flickering of the cabin lights seconds before crash. The veteran pilot says this description aligns perfectly with RAT deployment, which momentarily soaks up a lot of the aircraft's electrical reserves so that there is a visible drop or dimming of lights and electrical systems get interrupted because the system transitions from engine-driven generators to emergency power. This also creates a loud sound as the RAT deployment door opens, he adds.

Air India AI171 crash: RAT was not enough

Talking about situations in which RAT deployment suffices, the veteran aviator explains why it was not enough to save flight AI171 from crashing. He says, "Now the RAT was originally designed—and it's on all these airplanes—as a backup, the last resort, the absolute last resort. It's assuming that there's going to be basically a dual engine failure at altitude. Let's say you're at 30,000 feet, both engines flame out for some reason, you start descending down, you're looking for a suitable field, you're out of hydraulics and you're out of electric because both of your engines have stopped running. Maybe the auxiliary power unit isn't running, but it's not going to get you any thrust either. And so let's assume that's out. At that point, you've got to have some sort of electrical so you can talk on the radios, so you can have some sort of an approach and get some sort of instrumentation in front of you. And then you have to have some sort of hydraulics to still fly the airplane. It gives you the minimum of all of those categories that I just mentioned, but it does work."

Then he explains why even RAT deployment couldn't save the Air India flight from the crash, and says, "But it's meant for the airplane to kind of cruise down now and find a place to land. It's not designed for an airplane that's at 4 or 500 feet and loses all power. There's no time to get the engines relit. No benefit to them except it's evidence for us that it was a dual engine failure most likely. Could it have been an electrical issue? Could have been a hydraulic issue? Yeah, it could have been either one of those. But I think the fact that the airplane is now just kind of mushing out of the sky gives us the idea that it was a dual engine failure. But we can hear it, so there's confirmation number two. We've got the visual that we can see the RAT deployed, we can hear it with our ears."

While the new bits of evidence points towards dual engine failure, it raises significant questions about what could cause simultaneous failure of both engines on a modern Boeing 787 immediately after takeoff.

The aircraft reached only 672 feet before crashing, leaving investigators to determine why both GE GEnx engines would cease functioning almost simultaneously during the critical climb phase.

Captain Steve mentions that the watchdog Aviation Herald had ruled out bird strike initially, while observing that no remains of bird/birds was found on the runway. Although it had disputed the dual engine failure theory, the new evidence may require it to reconsider its findings.

A lot hinges on the black box data, which will be able to confirm the precise sequence of events and if RAT was deployed due to dual engine failure or other emergency circumstances.