Questions tagged [braking]

Questions about usage of mechanical brakes on the wheels for slowing down.

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19 votes
4 answers
2k views

What ground speed reference is used for anti skid control?

I was reading about slip ratio controlled anti skid system and had this one particular question in my mind. In addition to the wheel speed data, slip ratio controlled systems need a ground speed ...
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  • 191
26 votes
6 answers
6k views

Do airplanes really expose their internal wires and electronics like this on the wings when braking?

While watching a video today about airplanes and how they have little thingies on their wings to make them come to a stop much quicker than otherwise, I noticed something very odd: Are those cables ...
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14 votes
4 answers
4k views

What causes a Cessna 172 and its gear to shake violently after landing and braking?

I am sure this was due to my own ignorance on proper technique, but immediately after landing in a Cessna 172, I applied brakes and some moderate aerodynamic braking and experienced an awful and ...
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23 votes
2 answers
6k views

Is this aerodynamic braking procedure normal in a 747?

I found this instagram video via YouTube: The description in the YouTube video states that: This aerodynamic baking procedure is applied to reduce wheel brake and engine wear I have two questions: ...
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  • 1,725
4 votes
1 answer
256 views

Is there a name for the fast decline + pull to climb pattern?

I'm a hobby photographer and I've noticed some patterns in the bird flights, so I tried to poke a bit into the aviation terminology for it. Phalacrocorax carbo does this movement similar to the ...
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7 votes
2 answers
1k views

How does an inoperative Anti-Skid affect V speeds?

I am trying to figure out why is it that when you have an inoperative anti-skid system, the calculated V Speeds are lower? I'm trying to see this from a performance perspective, could this be due to ...
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2 votes
3 answers
396 views

Are there any GA trainer aircraft without toe brakes?

I'm a student pilot, and I've built about 20 hours on a Cessna 172. I also have an old ankle injury that makes it hard to bend my left ankle, and I'll probably be getting an ankle fusion later this ...
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  • 521
8 votes
1 answer
1k views

What's the difference between multiple disc brake and segmented rotor brakes?

Going through FAA's aircraft maintenance manual I came across a topic under braking systems, which had two different types of brakes: multiple discs and segmented rotor disc brakes Looking at the ...
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8 votes
2 answers
2k views

Could an airliner abort a landing after using the brakes system while landing?

Everyone knows that doing a go-around is a normal procedure, although the go-around happens usually before applying the brakes system (spoilers, ground/air brakes, and/or thrust reversers), but, could ...
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1 vote
3 answers
197 views

Can water-cooled brakes be used for takeoff aborts?

Airliner engines are sized to continue the takeoff if one engine fails after it has become too late to brake. This means that the oversized engine has to be lugged around the whole flight, increasing ...
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  • 3,084
1 vote
1 answer
381 views

Why does the DC-9's antiskid system have to be manually disarmed during landing rollout following a ground-shift-mechanism malfunction on takeoff?

An aircraft's ground-shift mechanism (usually a sensor wired to the nosegear strut that looks to see whether the strut is compressed or not) tells the aircraft whether it's on the ground or in the air....
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  • 26.1k
5 votes
1 answer
229 views

Why use thrust reversers? [duplicate]

I see a lot of planes using thrust reversers and stopping in the middle of the runway in plane spotting videos, but I don't understand why they do it when they can obviously not use the reversers and ...
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2 votes
1 answer
132 views

How does keeping the parking brake applied when brake temperatures are high contribute to the dragging brake phenomenon?

While going through a presentation on the Airbus WIN application with regard to cost saving practises. It was told with regard to brake life. If the parking brake was applied when the brake ...
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  • 1,682
0 votes
2 answers
2k views

Why does the A320 have an anti skid system and how does it work? [duplicate]

Can somebody explain why do A320 aircraft have an anti skid system? What is its purpose? And a brief explanation on how it works.
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  • 1,643
2 votes
3 answers
292 views

If the pilots used the brakes upon landing, would the force essentially slam the front wheel down?

So if the pilots braked immediately, with only the back wheels down, and nose wheel still up, would the force from braking cause the front wheel to come slamming down?
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15 votes
4 answers
5k views

Why does the Eurofighter Typhoon pitch up on brake release?

In the video here of an airshow take-off, it's noticeable that when the brakes are released there's a brief but pronounced fluctuation in pitch as the aircraft accelerates. This is something you see ...
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  • 9,431
16 votes
1 answer
3k views

What is the "Brake to Exit" feature on the Boeing 777X?

I have come across a new feature called BTE (Brake to Exit) on the 777X, but I am unable to find any documentation related to that. There are vendors who are working on this technology for the 777X.
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  • 6,809
8 votes
2 answers
3k views

What powers the air required for pneumatic brakes in aircraft?

What powers the air required for pneumatic brakes in large airliner aircraft? Is it bled from the engines, or do they have a separate motor and pump?
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10 votes
2 answers
2k views

How far would a landing Airbus A380 go until it stops with no brakes?

If an Airbus A380 lands with all brakes disbled, including reverse thrust, wheel brakes and any other measures it has to stop or slow down. Then how long would it take it to reach a complete stop.
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4 votes
1 answer
353 views

How should ground crews act to safely extinguish an airliner's brake unit fire?

When the brake unit was overheated and had just begun to catch fire due to excessive braking because of long taxi distance upon arrival, the ground personnel (not firefighters) made the first ...
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27 votes
4 answers
8k views

Why are thrust reversers not used to slow down to taxi speeds?

In reading this question (Would more throttle when using reverse thrust reduce stopping distance?), it prompted me to remember that on many of my flights (typically on 737s or CRJ type aircraft), it ...
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  • 1,545
-1 votes
2 answers
576 views

How are aircraft brakes applied? [duplicate]

I read somewhere that when both rudder paddles are pushed simultaneously it produces a braking effect. Is this true? If yes, please provide a detailed description of the above mentioned system.
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  • 29
6 votes
2 answers
5k views

What's the difference between setting auto brakes to MAX vs. RTO in Boeing Aircraft?

On Airbus aircraft, before taxiing and before take off, pilots turn auto brakes to MAX. But on Boeing aircraft, they will set auto brakes to RTO. Why does Boeing not use auto brakes MAX instead of ...
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9 votes
1 answer
1k views

Why does the flight controls check come before arming the autobrake on the A320?

As per SOP on the A320 we first perform the flight controls check and then arm the autobrake to max. What is the reason behind this?
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  • 1,682
1 vote
1 answer
140 views

What are the three sources that are relayed to the brakes and steering control unit of an A320?

There is the sentence: Electrical signals from the three sources are relayed to the brakes and steering control unit (BSCU) and are computed into the nose steering angle. The question: What are ...
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4 votes
2 answers
1k views

Why don't nose landing gears have brakes?

Nose brakes can help the aircraft in braking and it can also help in reducing the travel on the runway length. So why don't we use brakes in the nose landing gear?
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1 vote
1 answer
256 views

Do any aircraft have liquid-cooled brakes?

Aircraft wheelbrakes, especially those on heavy aircraft, get really, really hot during landings and rejected takeoffs, and cool down very, very slowly without active cooling. This imposes limits on ...
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  • 26.1k
2 votes
2 answers
603 views

Why don't commercial aircraft have drag chutes for aborted takeoffs? [duplicate]

We were watching the program Air Crash Investigation and there was an episode where it was too late to abort the take-off and the pilots had to attempt to climb still but since an abort was not ...
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  • 5,951
1 vote
2 answers
195 views

What is the 'fuel cost' of a pneumatic braking system vs. a hydraulic one, in terms of weight?

A pneumatic braking system has indisputable advantages over a hydraulic braking system for large and heavy aircraft in terms of braking force and secondary perhaps in terms of weight (pipes and ...
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12 votes
1 answer
666 views

Why is braking action (with Anti-Skid) best when the wheel rotates at ~85% of the actual speed?

During my ATPL training the subject of tires and braking was discussed. I understand the principle of the anti-skid and also the differences between aircraft and similar systems in cars. Physics also ...
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2 votes
2 answers
1k views

What happens if an A320 goes to full throttle with the parking brake set? [duplicate]

The question is simple: what happens? Is the aircraft going to stay stationary, or will the engine power overcome the brakes? I'm assuming everything is fully functional. I know the FCOM says not ...
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  • 3,832
12 votes
2 answers
3k views

Is aerodynamic braking really effective?

(YouTube) In the frame above the pilot is pulling back, as evident by the stabilator's position, and this technique is usually cited as a means of slowing down. But wouldn't the brakes have better ...
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2 votes
1 answer
201 views

How can I reduce the responsivness of my homebrew brake system?

I have a hydraulically actuated aircraft brake system. Each main landing gear are equipped with brake disk hydraulically operated. The actuation is realized independently for each wheels by means of ...
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5 votes
3 answers
586 views

Do large Airliners use full thrust when reversers are deployed?

Do large and heavy Airliners, Jumbos and Super Jumbos wide bodies included use full thrust for braking when reversers are deployed? What is the thrust setting?
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4 votes
2 answers
451 views

Engines more powerful than the brakes?

This might be more of an anecdotal question, but are there any aircraft where under full throttle (with afterburner in worst-case) where the wheels wouldn't provide enough friction against the runway ...
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  • 1,545
3 votes
2 answers
727 views

Why is V1 based only on using brakes?

V1 is the speed that an aircraft may abort a takeoff so long as the airspeed is below it, or is committed to flight if it is over that speed. V1 calculations are based only on the brakes (not sure ...
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  • 11.2k
9 votes
3 answers
4k views

Why are parking brakes not used for parking jetliners?

From the question 'Do I Set the Parking Brake On the Ramp?' it is concluded that you do not set the parking brake when parking the aircraft. The question concerns small aircraft which can be parked ...
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3 votes
1 answer
241 views

What guidance is there for pilots when reporting braking action?

I was listening to "[REAL ATC] Eastern B737 (candidate Mike Pence) OFF RUNWAY at LaGuardia!"(1) and the LGA Tower asks for and receives reports of braking action from several landing pilots. I assume ...
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  • 10.8k
24 votes
6 answers
5k views

Would increasing the number of wheels of a Jumbo reduce the braking distance?

If weight was not an issue, would increasing the number of main gear wheels on a jumbo such as the Airbus A380 from 20 to 40 wheels, each equipped with braking disks and braking equipment, considering ...
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13 votes
3 answers
3k views

Why aren't there brake lights on aircraft?

Why don't aircraft have brake lights so you can see when an aircraft in front is slowing down? I know there are air traffic controllers to control aircraft but they cannot do much about an aircraft's ...
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8 votes
1 answer
1k views

Does the 747-8 / A380 nose-wheel encounter more weight during braking?

Given that the nose wheels of both the Boeing 747-8 and Airbus A380, as is true for almost all aircraft, are not equipped with brakes, do they encounter more weight during braking? If so, how much ...
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5 votes
1 answer
713 views

On the new A320s when we do a brake check there is no need to call pressure 0 why?

Why do we have a give a pressure 0 call out when checking brakes while taxi on the old A320s but not in the newer A320s.?
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  • 1,682
1 vote
0 answers
978 views

Can MIL-PRF-5606H hydraulic fluid be used in place of MIL-PRF-5606?

Can MIL-PRF-5606H hydraulic fluid be used in place of MIL-PRF-5606? My airplane is a 1966 Piper Cherokee 6.
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4 votes
2 answers
2k views

Why do we have to do an alternate brake check during preliminary cockpit preparation?

As part of the preliminary cockpit preparation in my company’s older A320s we have to perform an alternate brake system check but not in the newer ones as per FCOM Normal procedures as below. I found ...
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  • 1,682
5 votes
1 answer
156 views

Does the weather condition of the runway affect the braking of an aircraft with regards to wheel braking and reverse thrust?

I was on a 737 that landed on a snowy runway in northern Finland the other day. We had to wait around 30 minutes to land as they were waiting for it to stop snowing and then for them to clear the ...
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17 votes
5 answers
11k views

Why does an aircraft not spin out of control right after touch-down?

When a plane is landing, how does it not immediately start spinning out of control? Given the massive amount of forward momentum and the fact that all the various braking forces (wheel brakes, ...
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3 votes
3 answers
437 views

Why do we often have more than one method of slowing down (retarding) aircraft on the ground?

Why do we often have more than (thrust reversers and brake chute) one method of slowing down (retarding) aircraft on the ground?
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8 votes
3 answers
2k views

How much force are large aircraft brakes able to exert?

In a comment left on my answer here Jan Hudec says: Note that usually on dry surface the brakes exert much less force than the tires could handle. This got me wondering how much force large ...
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  • 27.5k
2 votes
1 answer
373 views

How does the forward speed of an auto-gyro relate to the rotation speed of the rotor during auto-rotation?

In my other question I was looking for a relation between the forward speed and the thrust (lift) of an auto-gyro. I have come to the conclusion that for an auto-gyro in auto-rotation the forward ...
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  • 31
4 votes
4 answers
1k views

Is it feasible to recuperate energy from landing aircraft by using a runway sled with regenerative braking?

Would it be feasible to land large (Boeing 747 and Airbus A380) and all other aircraft on a sled on the runway, the kinetic energy of the aircraft is then transferred to the sled, then the sled uses ...
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