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Questions tagged [braking]

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

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15
votes
1answer
2k 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.
8
votes
2answers
2k 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?
10
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2answers
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.
3
votes
0answers
132 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 ...
26
votes
4answers
7k 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 ...
-1
votes
2answers
186 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.
5
votes
2answers
333 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 ...
9
votes
1answer
702 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?
1
vote
1answer
84 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 ...
4
votes
2answers
467 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?
1
vote
1answer
140 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 ...
2
votes
2answers
390 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 ...
1
vote
2answers
151 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 ...
11
votes
1answer
403 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 ...
2
votes
2answers
725 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 ...
10
votes
2answers
839 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 ...
2
votes
1answer
154 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 ...
3
votes
2answers
363 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?
3
votes
2answers
490 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 ...
8
votes
2answers
2k 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 ...
3
votes
1answer
154 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 ...
22
votes
6answers
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 ...
12
votes
3answers
2k 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 ...
8
votes
1answer
762 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 ...
5
votes
1answer
375 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.?
1
vote
0answers
499 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.
1
vote
1answer
516 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 ...
5
votes
1answer
108 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 ...
17
votes
5answers
9k 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, ...
3
votes
3answers
342 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?
8
votes
3answers
942 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 ...
2
votes
1answer
250 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 ...
2
votes
4answers
785 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 ...
3
votes
1answer
174 views

What is typical thrust to braking force ratio for a passenger airliner?

Is the ratio fairly constant across aircraft types, sizes and powerplants? I'd like to ignore the reverse thrust component, since that's not available at the same time as forward thrust.
54
votes
4answers
10k views

How do seaplanes do run-up checks without brakes?

Usually on run-up you want to check the response of the motor when changing for example the carb-heat (if existent). At least we did so on my intro flight (yey!). To prevent us from rolling onto the ...
11
votes
1answer
2k views

Why are brake temperature limitations lower when the brake fans are running?

In the A320 FCOM it is stated that if the brake fans are running prior to takeoff then the brake temperature must be below 150 degrees Celsius. But if the brake fans are off then our limitation is 300 ...
6
votes
2answers
255 views

Are the captain's and first officer's brake pedals always mechanically linked?

I heard that for Boeing and Airbus aircraft, the pilot's and copilot's brake pedals are mechanically linked, is that true? Why did they make that design decision? What's the advantage? Do all kinds ...
18
votes
4answers
9k views

Why do aircraft have two brake pedals instead of one?

Why do aircraft have two brake pedals instead of one? If each pedal controls different sets of wheels e.g. the left wheels and the right wheels of the main gear, is that not a safety flaw given that ...
5
votes
2answers
387 views

What is the effect of sudden extreme temperature change on brake disks of large aircraft?

What is the temperature of brake disks at maximum altitude of a jumbo like a 747 and airbus A380 for say a 10 hour flight. Does the temperature drop below zero and what is the effect on the metal ...
2
votes
0answers
91 views

Why is there only circumferential treading on the nose wheel? [duplicate]

The pilot uses the nose wheel for steering on the ground, still all the tires on the aircraft use the same treading. Why are there no treads perpendicular to the rotation direction? I know that most ...
5
votes
3answers
1k views

Do parking brakes lock the wheels and airframe together?

(YouTube) Wildcat undercarriage. For planes with non-truck undercarriages, can they be rotated around the lateral axis of the main landing gear with the brakes applied without causing translation? ...
19
votes
3answers
4k views

Would a stationary WWII fighter fall on its nose with full throttle and brakes on?

Would a stationary WWII fighter fall on its nose with full throttle and brakes on? It's a general question, but I am interested in the Republic P-47.
-5
votes
1answer
3k views

How do multiple-disc brakes work?

Multiple disc brakes uses stators & rotors to brake? How do they work? (Source)
1
vote
1answer
269 views

What brakes are used between line-up and takeoff?

I was wondering if an airliner was instructed to line-up on the runway ("line-up and wait"), will the park brake be used or will manual braking be used (pedals) during the wait until the take-off ...
3
votes
3answers
754 views

Have Eddy current brakes ever been used/tested on an aircraft?

Eddy current brakes (wiki) --- a.k.a. magnetic brakes --- get quite some attention from train engineers. They are used on Shinkansens, roller coasters, and even (as far as I know) metro trains on Lane ...
5
votes
1answer
3k views

How often are heavy aircraft brake pads changed?

How often are Boeing 747-800 and Airbus A380 aircraft brake pads changed?
10
votes
4answers
2k views

What is the preferred way to slow down an airliner on a long runway?

EDIT: Another way to phrase the question is, given an extra long runway, does it make sense to substitute mechanical braking (which is the primary way to slow down in a typical situation) partially or ...
20
votes
3answers
9k views

What is the temperature of the brakes after a typical landing?

On an airliner, what is the temperature of the brakes after a typical landing, and how long does it take to cool down? Is it hot enough that mechanics should wait before servicing an aircraft that ...
6
votes
1answer
345 views

How does EMAS reduce damage in case of an aircraft overrun?

I saw a report about Mike Pence's plane overrun today on Twitter link: Mike Pence plane overrun photo on Twitter. As can be seen there is huge cracks and breaking of the runway but the plane was ...
0
votes
1answer
259 views

Can an aircraft (civilian or military) land with its brakes already engaged? [duplicate]

Can an aircraft land with its brakes already engaged at the max landing speed of that aircraft?