Originally Posted by
FullWings
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?”