Brakes or Reversers
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Brakes or Reversers
Dear Friends! You can use brakes intensively on landing roll and you can use max reverse thrust. What is cheaper, in the end, I mean maintenance costs (noise abatement and runway conditions are not a factors)? Thank you.
Depends on your contracts. A few years ago we were asked to always use the highest amount of reverse thrust possible to save on brake wear. Nowadays we nearly always use only idle reverse and higher auto-brake settings or manual braking. The difference is purely in our maintenance and leasing contracts. Presently brake wear is included in our leasing contracts, engine maintenance isn't.
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OK! In this case I would like to find out how use of max reverse thrust increases engine maintenance costs (some digits please if you have). When I was taught to fly Boeing, my Alteon instructor told me: "we pay for brakes and we don't pay for reverse thrust".
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Engine maintenance is normally based on cycles and hours. Reverse adds to neither. The added fuel might be a real cost.
Steel brakes might overheat without reverse thrust, causing excess wear and/or tire blowouts. That is not normally a problem with carbon brakes.
Steel brakes might overheat without reverse thrust, causing excess wear and/or tire blowouts. That is not normally a problem with carbon brakes.
Both ! Brakes and Reverse.
If, as we keep telling ourselves, we must put safety before cost, then we need a mindset which plans to use all available means of stopping.
If a landing (speed, TCH, touchdown position, etc) and initial deceleration progresses according to plan, then ‘cost aspects’ may then be considered. This could involve the degree of use or priority of brakes vs reverse.
Reverse thrust is more effective at high speed and thus should always be deployed as soon after touchdown as possible, particularly with systems which create drag without high engine speed, e.g. buckets.
Brakes provide proportionally more deceleration at lower speed, and if braking is progressively increased where the aircraft’s energy has been reduced, then heat / wear problems may not be so great. Aspects of most autobrake systems provide this feature.
Using brakes up to maximum application should not cause any safety problems, even if they get hot.
Although landing performance is predicated on brake use only, the assumed safety margins are not always assured, particularly in wet conditions. Reverse adds safety margin.
For EU operations with approved contaminated landing data, the performance may be based on both max brakes and reverse – read the small print.
A strict company procedure for one system or the other is likely to bias crew’s decision making, which on rare occasions may compromise safety. Reverse / brake wear is cheaper than an overrun.
A well informed management should allow pilots to decide what to prioritise based on the landing conditions; it’s their decision.
If a landing (speed, TCH, touchdown position, etc) and initial deceleration progresses according to plan, then ‘cost aspects’ may then be considered. This could involve the degree of use or priority of brakes vs reverse.
Reverse thrust is more effective at high speed and thus should always be deployed as soon after touchdown as possible, particularly with systems which create drag without high engine speed, e.g. buckets.
Brakes provide proportionally more deceleration at lower speed, and if braking is progressively increased where the aircraft’s energy has been reduced, then heat / wear problems may not be so great. Aspects of most autobrake systems provide this feature.
Using brakes up to maximum application should not cause any safety problems, even if they get hot.
Although landing performance is predicated on brake use only, the assumed safety margins are not always assured, particularly in wet conditions. Reverse adds safety margin.
For EU operations with approved contaminated landing data, the performance may be based on both max brakes and reverse – read the small print.
A strict company procedure for one system or the other is likely to bias crew’s decision making, which on rare occasions may compromise safety. Reverse / brake wear is cheaper than an overrun.
A well informed management should allow pilots to decide what to prioritise based on the landing conditions; it’s their decision.
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Using brakes up to maximum application should not cause any safety problems, even if they get hot.
It is NOT a trivial safety issue.
So you have normal landing data including the use of reverse? Or like the rest of the world is your landing data for dry runways predicated on not using reverse?
By the way, how much engine wear is increased by reverse depends on type of course. In the 737 it is apparently a major factor due to the high risk of FOD ingestion and other unpleasant stuff. However i do agree with safetypee, it should always be at the discretion of the crew how much of either deceleration device is used. And in fact while my company prefers using idle reverse only (no reverse is not allowed) we are of course allowed to use more if needed.
By the way, how much engine wear is increased by reverse depends on type of course. In the 737 it is apparently a major factor due to the high risk of FOD ingestion and other unpleasant stuff. However i do agree with safetypee, it should always be at the discretion of the crew how much of either deceleration device is used. And in fact while my company prefers using idle reverse only (no reverse is not allowed) we are of course allowed to use more if needed.
