BBC: Brazil jet thrust reverser 'off' ( No wonder he was speeding down the runway)

BBC ^ | Friday, 20 July 2007, 09:31 GMT 10:31 UK | BBC Staff

[skeptoid]

This accident reminds me of the Alaska Airlines 727 overrun at Ketchikan, Ak (PAKT)on April 5 '76 (50 souls/ 1fatal/ a/c destroyed).

After an unstabilized approach, landing fast and long, and committing to a full stop, he tried to go around, but there was a known problem stowing reverers above 40 knots, and they ran out of runway, airspeed and options.
The NTSB Report has interesting sections on survival aspects, spoiler effect on braking, and reverser operation on pp13-20 (PDF pp15-23).

[zipper]

However, the function of the spoilers is to reduce the lift component which in turn makes the brakes more efficient/effective.

Yes, that's what I said in my post (#51).

Autobrakes are usually pretty good. The problem is that as soon as the pilot tries to override them, the net result is less brakes as it is physically impossible to exert more pressure than the max brake setting.

Yes, it is impossible for manual braking to do better than 'max' autobraking, once the brakes are applied -- assuming 'max' autobraking was selected to begin with. If a lesser deceleration gradient such as 'minimum' or 'medium' were selected then taking over manually would have been appropriate. The 'max' brake setting is abrupt and uncomfortable for the passengers (at least on a dry runway). It means full braking, according to a preset deceleration gradient, close to triggering antiskid-activated wheel release. In this situation the max autobrake setting would have been appropriate, but the slick conditions worked against them. They also may have been fast, landed long, spoilers may not have deployed (may not have been armed per the checklist), etc. It didn't help that the asphalt was new, which means water beads more, contributing to hydroplaning -- and worst of all the runway wasn't grooved.