How to TOTAL a BA-146 Commuter Plane

[ExiledTaff]

dr_gn said:

dvs_dave said:

I find it hard to believe that such a situation would be allowed by the aircraft's control system? Only 2 engines running, the throttles able to be set for take-off with no hydraulic pumps running......yea right!

I should think the true explanation is a lot less "stupid americans" like.

The first post says that the reason for no brakes was that the engines running didn't have hydraulic pumps, but it also says that the Auto Throttles were set in Take-Off mode. (Which disconnects the Brakes), in which case the engine issue was irrelevant (I think).

So which was it? Or was it both?

IIRC, the auto throttle only works above flight idle, with the weight off wheels, so unlikely to have had any bearing on the incident.

Re: hydraulics, if the a/c was taxying* on the outboard engines, then brake pressure should have been provided by the AC pump in the yellow system. Which, in turn, powers the green system via the PTU (power transfer unit) which provides pressure to the steering system.
So, if they had steering available, then brakes would also be available.
If all hydraulics dropped offline, then by selecting emergency brakes, the DC pump is energised, which can provide more than enough pressure to stop a taxying aircraft.



* yes that is the correct spelling