Airbus Braking Styles
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Airbus Braking Styles
I have noticed various pilots use different branking styles on Airbus FBW aircraft. Eg. Same runway, same conditions, same aircraft (A420) but one pilot decides to use LOW braking with FULL reverse. Other pilot uses MED braking with IDLE reverse. Do different airlines have different SOP's or is it pilots choice for braking?
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I am not an Airbus driver, but according to your question this has not much to do with fly by wire aircraft, it is more a question of autobraking system.
In Europe we often use Idle reverse to comply with airport noise reduction requirements and therefore you need to add more braking in to stop in the same distance. Anyway you are free to use full reverse thrust anytime safety becomes an issue.
In Europe we often use Idle reverse to comply with airport noise reduction requirements and therefore you need to add more braking in to stop in the same distance. Anyway you are free to use full reverse thrust anytime safety becomes an issue.
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It also has to do with the type of brakes fitted. Our carbon brakes are better left to do all the stopping on uncontaminated surfaces. And the company thinks this is cheaper too. So always just idle reverse unless other factors require more. Nice to the neighbours too. 
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The FBW auto brake settings are predetermined deceleration rates and therefore the braking system modulates the pressure to achieve the requested rate when autobrake is used. With Low selected the reverse thrust on anything higher than idle can result in no actulal braking on the wheels. This is no real problem apart from cost, since with carbon brakes its the number of apllications rather than the time and pressure exerted that cause wear. So idealy low reverse and low auto brake will be used together.
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At my company, idle reverse and as required autobrakes is normal for landing. The main reason is fuel saving. Idle reverse burns less fuel, and allows you to shut one engine down sooner on the taxi in. The wear on the carbon brakes is not significant on landing, as they are warmed up to operating temperature.
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This question is as old as there are brakes in aviation! It's basically a philosophical question, and to that everyone has its own opinion.
Important to notice is that aircraft with iron brakes (the "older" aircraft") depended more on max reverse and minimal braking, to save money and brakes. The newer aircraft have carbon brakes (carbon fibre, like the one on formula one cars), have slightly different braking characteristics, can absorbe much more energy (i.e. can brake better), cost more, but less per braking cycle. With the increase of fuel prices, it has become practice to safe it, use idle reverse and let the brakes do their work.
So you might still see "older" pilots using the "old" technique, also in classical major airlines, because they learned it that way.
Interesting is also that newer aircraft designs depend less on reverse. They also found out that its more economical, and you can safe weight and costs. The A380 e.g. was originally designed without reversers, which was then refused by some customers, the actual design has only two reversers (on the inboard engines).
There are of course special situations, as mentioned before, if you have contaminated runways you use full revers, or if you have to follow noise restrictions, you use idle reverse, if you can.
hth,
Dani
Important to notice is that aircraft with iron brakes (the "older" aircraft") depended more on max reverse and minimal braking, to save money and brakes. The newer aircraft have carbon brakes (carbon fibre, like the one on formula one cars), have slightly different braking characteristics, can absorbe much more energy (i.e. can brake better), cost more, but less per braking cycle. With the increase of fuel prices, it has become practice to safe it, use idle reverse and let the brakes do their work.
So you might still see "older" pilots using the "old" technique, also in classical major airlines, because they learned it that way.
Interesting is also that newer aircraft designs depend less on reverse. They also found out that its more economical, and you can safe weight and costs. The A380 e.g. was originally designed without reversers, which was then refused by some customers, the actual design has only two reversers (on the inboard engines).
There are of course special situations, as mentioned before, if you have contaminated runways you use full revers, or if you have to follow noise restrictions, you use idle reverse, if you can.
hth,
Dani
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Refer flap15's comments:
1. For carbon brakes, each application is a wear cycle. So, multiple brake applications result in more wear/cost.
2. Ironically, a low Autobrake setting can result in multiple applications (more cost), wheras a higher Autobrake setting may result in fewer brake applications (less wear on carbon brakes).
This is why Boeing recommends a higher Autobrake setting in normal operations rather than a minimum setting.
1. For carbon brakes, each application is a wear cycle. So, multiple brake applications result in more wear/cost.
2. Ironically, a low Autobrake setting can result in multiple applications (more cost), wheras a higher Autobrake setting may result in fewer brake applications (less wear on carbon brakes).
This is why Boeing recommends a higher Autobrake setting in normal operations rather than a minimum setting.
