Better to slowdown an airplane with brakes or with reverse engines?
Does anybody knows whether slowing down an airplane with reverse engines creates is more costly that stopping it with brakes? What about pollution?
- 1 decade agoFavorite Answer
In the Metroliner (turboprop) I seldom use the brakes at all on landing. Reverse, and differential reverse, give me a lot more control on the runway. I'm used to landing on icy/rainy runways and the brakes can get you into a world of hurt (think about using your car brakes on a road-- now imagine trying to use them going 110mph down a mile long stretch of road). Even without slippery runway conditions I'm so used to using the reverse, I seldom use the brakes unless going into a very short field. You'll find brakes are a lot less reliable then reverse (brakes seem to fail-- not a lot-- but it's definitely not unheard of) and require a lot more maintenance if used on a regular basis. My props do get eaten up a little but from picking up sand/rocks-- but not so bad if you never pull it into deep (full reverse). As for the pollution... I don't care how environmental minded a pilot is... pollution is the last thing on your mind when landing an airplane.
Mind you, I'm not a jet pilot so their answers may be accurate-- but from a turboprop driver's perspective, brakes really aren't needed.
- Larry454Lv 71 decade ago
From an engineering perspective:
Turbine engines are limited by the number of cycles that they encounter. Each time you run the engines up with the thrust reversers, you take a little fatigue life out of the rotors, as well as the engine support structure. Replacing brake components is very inexpensive compared to doing a hot section on an engine. Thrust reversers are there if you need them, but I would prefer the use of brakes.
- KissthepilotLv 61 decade ago
A modern jet is stopped by brakes, ground spoilers and thrust reversers, in that order. And, the main reason for the ground spoilers is to kill the lift and increase the effectiveness of the brakes to stop the aircraft. Thrust reverse isn't even used in the calculations for stopping distances for jets, unless you are landing on a slippery runway surface. When you are stopping an aircraft, you don't really think about pollution, as safety is much more important. The engines do produce some exhaust, but it's only for a few seconds during the reverse operation. I have no idea which costs more, as again, safety is more important that cost. It costs a lot more to run off the end of a runway, so you take care of stopping the aircraft before you worry about the cost.
- Anonymous1 decade ago
There is hardly any effect of more pollution with applying the thrust reversal according to my knowledge and another technicle thing is that when the aircraft touchs down it has an imence speed an its really very difficult to stop that thing with the brakes the wear and tear is too much as compared to the the trust reversal which is only the design modification so the first the aircraft is stopped with trust reversal and then with help of brakes at the final end so this is how its is working.
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- 1 decade ago
Everyone pretty much hit this one on the head, but there's one thing that wasn't mentioned - brake fading. This is where the rotors and pads get hot enough that their co. of friction and stopping power drop off. Traditionally, the drill is to use spoilers and reverse thrust after nosewheel touches, until (around) 60 kts, then use brakes to stop the aircraft. If you touch down at 110 kts with a tailwind, and only use brakes to stop, you could find yourself in a bad situation. Semi truck and garbage truck drivers have to fight this constantly.
- 2OleGENDLv 61 decade ago
It depends on what situation. In rainy weather or icy runway, it is usually better to use thrust reversers(thats not to say that braking couldn't do the job but reversers are a bit more effective). But in noise restricted Airports like Heathrow, it is better and less polluting to use brakes because. thrust reversers are a noisy.
- 1 decade ago
All planes use brakes to slow down period. The reverse thrust only occurs when really neccessary althought most pilots will do the reverse for about 3-5 seconds to really reduce the momentum and speed. One flight to Atlanta, the tailwind was 10+ and the pilot used the reverse for a while simply because the wind kept pushing us.Source(s): Frequent Flyer Behind the Wing
- miiiikeeeLv 51 decade ago
Use thrust reverser's and little less brakes. Just had to go out and pull 2 brakes off and throw the tires back on to get the pilot off the taxiway cause he used to much brake and then set the parking brake when he was waiting to cross active .He seized up the brakes. Had to cover pilot and say it was a bad control valve.
- 1 decade ago
Most procedures call for the use of breaks to slow down over thrust reversers, however I know there is some debate that it is less costly to use the TRs.
Where TRs are used on the ground... you will see many NorthWest DC-9's use TRs to pushback as it is cheaper than getting a tug out there.
Hope this helps.
- 1 decade ago
It can cost a lot more, and create a lot more pollution to slow down slower (?) and miss a taxiway by not using reverse and therefore have a longer taxi, burning more fuel for a longer time. If you miss a taxiway, it can add distance and many minutes to your taxi to the terminal. The guy who stops the fastest and gets off the runway soonest will generally have his engines shut down at the gate a lot quicker, creating 0 pollution.