PPRuNe Forums - View Single Post - Rote use of autobrakes when operationally unnecessary
Old 12th Jul 2009, 19:40
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On-MarkBob
 
Join Date: Mar 2006
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AutoBrake

Some Airlines 'Buy' their brakes in a similar way to how they 'Buy' their engines and other components. You've, no doubt, heard of 'power by the hour' refering to the purchase of engines and APUs and such. A contract from a brake supply company may well specify a charge dependent on the use. To guarentee a high average for that use the agreement might specify the use of 'AutoBrake level 2', for example. To guarentee a high level of Autobrake 1 would suggest that the company would wish to land at airports with only very long runways. Companies using predominently short runways might have to specify normal use of Level 3, and thus pay more.
What we are looking at, at the moment, is the cost of reverse thrust against that of modern brake units. Early days yet, but it would appear that the cost of reverse thrust, including its 'mishandling' by piolts (eg. full reverse at speeds less than 80Kts. and not stowed below 60Kts) causing expensive FOD (damage) that outways the cost of using the brakes. Thus, using 'idle reverse' normally, unless necessary to use more, and better 'knowledge' of Autobrake application, is likely to be a serious option.
The down side is that pilots can sometimes have too much faith in the autobrake system and do not react fast enough when things start going pear shaped. There has been a number of runway over-runs where the pilots did nothing and then claiming that the autobrake did not do a proper job. I personally think that all pilots should be able to use manual breaking on a regular basis, so that they get a proper 'feel' for the brakes. This is particularly the case for some low houred F/O who often never get a chance to use them at all, except perhaps in the sim!!

Rgs. Bob.
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