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Quote:

Originally Posted by FullWings (Post 10509606)

I landed in BOM a couple of days ago and the runway seemed to be a bit grippier than I remember - has it been resurfaced? Anyway, I can confirm there was a lot of water about, three aircraft went around due w/s.

I think the proviso rarely applies, as from my experience, the worse the braking action, the more variability there is. Water/slush/snow/ice is rarely evenly distributed and you’ve likely got areas of rubber deposits around the TDZ at either end.

Autobrakes generally go for a fixed deceleration rate on anything but MAX, where they function like the ABS on a car with your foot hard on the brake: they extract the maximum stopping performance available at that instant. Consider a runway where the braking action of 50% of the surface (not necessarily in one bit) is worse than reported and 50% is better - using MAX will get more stopping in the good bits and the same in the bad bits, so a net win over an AB setting that technically should give the same result but may surprise you on the day.

Downsides of using MAX AB? Err, maybe a little bit more brake wear? Downsides of going off the end...

Agree mostly. On the A320 MAX is only for T/O. Don’t know enough about the B737, but landing performance on the A320 is better with full manual braking (like your car) than autobrake. Just the fact that there that many overruns suggests training/selection needs to change. Maybe less *have to get to the destination pressure?”

Really guys, you don’t know that different aircraft have different systems that work in different ways?
The NG has AB 1-2-3-Max for landing, RTO for takeoff.
Max can be used whenever it’s needed. Did that recently on a 1600 m runway and 63 T for landing. It uses a fixed retardation so more reverse give less brakes.
RTO is the full monty.
Landing runway 14 in BOM on a wet runway and 60+ tons LW you’ll be stupid not to use max.

It was fitted to our DC 10 as a mod. Crews were informed by a memo from the fleet TP, with recommendation to use light or medium but not full, until experience was gained and a feedback form had to be completed each time.

Next scene - pre landing in HKG dry RW and quite light - FE says Autobrake? Capt on check says Oh - er Better use light - Check Pilot says Try Full - FE says I have to fill a form and it says Reason for use - Check Pilot says Put Inquisitiveness.

The landing - Touch down followed by the most brutal retardation I have ever experienced before or since - talk about being thrown against the harness - IAS falls like a stone - Check Pilot shouts Disconnect - Captain on check shouts How? I (probably the only one who had read the memo) say, Brakes. Captain brakes and the ship feels as though released from a bow. We are now at about 30 knots and have to use Fwd thrust to reach the first exit...

Taxy in with red faces, left side anyway and hot brakes - Capt makes an announcement about a new bit of kit - not working properly, sorry etc.
All good useful experience for the first officer.