Air India 171 – RAT Deployment ANALYSIS
The last few articles on Air India 171 I focussed on the prelim report and different parts of it. In this article I look specifically at the RAT. When it was deployed, what does the deployment mean and does it make sense in the context of the fuel control switches?
Air India 171 RAT Deployment – Prelim Report
In the report it says the RAT was deployed immediately after take off.
Specifically the prelim report says this
The CCTV footage obtained from the airport showed Ram Air Turbine (RAT) getting deployed
https://i2.res.24o.it/pdf2010/Editrice/ILSOLE24ORE/ILSOLE24ORE/Online/_Oggetti_Embedded/Documenti/2025/07/12/Preliminary%20Report%20VT.pdf
during the initial climb immediately after lift-off (fig. 15)
What Does This Mean?
The way I read this is that the RAT deployed immediately after take-off while the engines were still producing thrust. While the engines were producing thrust because it says deployment happened during the climb.
Automatic Deployment or Manual RAT Deployment?
The prelim report is quite brief. We do not know what was going on in the cockpit “immediately” after take off so we can’t say if the pilots had a good reason to deploy the RAT manually.
If the RAT deployed automatically.
According to this post, there are three circumstances under which the RAT would deploy automatically.
In flight, the RAT deploys automatically if:
https://aviation.stackexchange.com/questions/98379/rat-deployment-and-stowage
- both engines are failed and center system pressure is low, or
- both AC transfer busses are unpowered, or
- all three hydraulic system pressures are low
Timing
If the RAT deployed automatically and before the flight control switches were recorded as being in the “Cutoff” position then I think this takes us back to square one. ie a catastrophic failure of some sort on the plane. A failure that led to the conditions listed above that would trigger RAT deployment.
Pilot Suicide – Realistic?
With this info, does the pilot suicide theory gain more or less weight?
I think the question we have to ask is does it make sense for a pilot committing suicide to deploy the RAT in advance of switching off fuel to the engines?
I think no.
And if the RAT deployed automatically and before the fuel control switches were changed then this points to a problem with the plane.
Air India 171 RAT Hydraulic Power – Flight Path
At 08:08:47 UTC the report says that the RAT began “supplying hydraulic power”
At 08:09:11 UTC the plane crashed.
That is 24 seconds of hydraulic power and yet the plane appears to make no effort to change course.
Why would it change course?
Because to the left of the crash site is open ground, landing here would surely be more preferable than landing on buildings. Why does there appear to be no effort made by either of the pilots to try and land in this open area?
Summary
It really comes down to the exact time that Air India 171 deployed the RAT deployment. It will give context to everything else. I guess we’ll just have to wait until that information is released.
