Did the Emergency Power Come On Before the Fuel Was Cut Off?

A forensic reconstruction of the Ram Air Turbine deployment on Air India Flight 171

Safety Matters Foundation • Captain Amit Singh • Boeing 787-8 VT-ANB • 12 June 2025, Ahmedabad

Air India Flight 171. Boeing 787-8, registration VT-ANB. 12 June 2025. This forensic reconstruction examines the exact moment captured in the AAIB Preliminary Report’s Figure 15 — a CCTV screenshot showing AI171 in its initial climb with the Ram Air Turbine already fully deployed — and what it tells us about the real cause of this accident.

Using only the dimensions published by Boeing, the EAFR (Enhanced Airborne Flight Recorder) data published by the AAIB, and elementary physics, we derive the height, speed, and time of the photograph from three independent methods. Every number is then cross-checked against a fourth, fifth, and sixth independent source — including the AAIB’s own data.

The Car Airbag Analogy

Think about a car airbag. An airbag only fires when the car has already hit something. You would never see an airbag inflated in a car that is driving normally — it means a crash has already happened.

The Ram Air Turbine on an aircraft is the same idea. It is a small wind-driven propeller that drops out of the wing root only when the plane loses almost all of its main power. If you see a RAT deployed, a serious failure has already occurred.

The 787’s Ram Air Turbine

On the Boeing 787, the RAT is the aircraft’s absolute last-resort power source. It is spring-loaded in a bay at the aft wing root. When the aircraft’s logic detects a catastrophic loss of power — both engines, or both main AC electrical buses — it releases the RAT automatically. The turbine drops into the slipstream, the blades spin up, and it generates just enough hydraulic pressure to keep the flight controls alive. Without it, the aircraft becomes uncontrollable.

One Photo + Three Timestamps

This is Figure 15 from the AAIB’s own preliminary report. A CCTV screenshot captured at Ahmedabad airport showing AI171 in its initial climb, just seconds after lift-off. The red circle highlights the Ram Air Turbine, clearly visible, fully extended, blades spinning in the airstream. This is the AAIB’s own published evidence. Nobody disputes this photograph.

The Problem: Sequence Matters

Here is the problem. The AAIB’s preliminary report states that the fuel cutoff switches moved to the CUTOFF position at 08:08:42 UTC. But this photograph shows the RAT already fully deployed — and the RAT only deploys when something catastrophic has already happened. So either the RAT came out before the fuel was cut, or after. The sequence matters enormously. Let us find out.

Step 1: Building a Ruler from the Wingspan

Boeing publishes the 787-8 wingspan as 60.12 metres, tip to tip. We measure that same wingspan in the AAIB’s photograph — it spans 214 pixels. Divide: 60.12 metres divided by 214 pixels gives us 28.09 centimetres per pixel. That is our ruler.

Every measurement we take from this image — the height of the tail fin, the distance from the ground — is anchored to this one verifiable, Boeing-published dimension. Nobody can dispute the wingspan.

Step 2: Height from a Right Triangle

Using the camera’s known position on the airport perimeter, the horizontal distance to the aircraft, and the upward viewing angle, we solve a right triangle: camera height plus distance times the tangent of the elevation angle.

The answer: approximately 20 metres above the runway — roughly 65 feet, about the height of a six-storey building. We cross-check with the tail fin: Boeing’s published 17-metre vertical stabiliser height measures correctly to within one percent in the same image. The geometry is solid.

Step 3: Speed from the Black-Box Data

We use the AAIB’s own black-box data as the anchor. The EAFR records Vr (rotation speed) as 155 knots at 08:08:35, and the peak speed of 180 knots at 08:08:42. That is a gain of 25 knots in 7 seconds, giving a measured acceleration of 3.57 knots per second. Both engines were clearly at full takeoff thrust right up until the instant of cutoff — there was no thrust loss beforehand.

At the photo time of 08:08:41, six seconds after Vr, the speed was 155 + (6 × 3.57) = 176 knots — about 327 kilometres per hour. We cross-check with the Crete perceptual blur metric: the image is sharp, consistent with sub-pixel motion blur at 176 knots. Everything agrees.

Step 4: Time from the Climb Rate

A 787 at full thrust climbs at approximately 10 metres per second in the first moments after lift-off. The aircraft is 20 metres above the runway. Twenty divided by ten equals two seconds of climb.

The EAFR records lift-off — the air-ground sensor transition — at 08:08:39 UTC. Add two seconds of climb. The photograph was taken at 08:08:41.0 UTC.

The Three Answers

Three numbers, derived from three completely independent physical methods:

The Full Timing Chain

The 787 RAT needs approximately 1.5 seconds of mechanical free-fall and lock-down from the moment the release command is sent to the moment it is fully deployed and visible. Subtract that from the photo time: the RAT release was commanded at 08:08:39.5 — half a second after lift-off, and 2.5 seconds BEFORE the fuel cutoff at 08:08:42.

Independent confirmation from the AAIB’s own data

The AAIB’s EAFR data records the RAT hydraulic pump supplying power at 08:08:47. Subtract approximately 6 seconds of hydraulic spin-up after full deployment: that gives 08:08:41 — matches the photo exactly. Subtract another 1.5 seconds of mechanical deployment: 08:08:39.5. The same answer, from a completely independent data source.

Five Independent Cross-Checks

In Plain English

Imagine a bank is robbed at nine o’clock at night. A CCTV camera at the shop next door shows the getaway car driving off at five minutes to nine — five minutes before the robbery was even reported. Can the police still say the robbery started at nine? No. The CCTV clock wins.

Same logic here. The AAIB says the fuel cutoff happened at 08:08:42. But their own photograph and their own black-box data show the RAT was commanded at 08:08:39.5 — two and a half seconds earlier. The photograph’s clock wins.

What This Proves: Three Findings

Key Numbers Reference

Every number in this analysis comes from Boeing’s published dimensions or from the AAIB’s own preliminary report. Nothing is assumed. Nothing is invented. The data speaks for itself.

Justice needs data. Data needs transparency.

Safety Matters Foundation • Captain Amit Singh • Admin@safetymatters.co.in
All data sourced from the AAIB Preliminary Report and Boeing Type Certificate Data Sheet.