Questions tagged [braking]

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

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5
votes
3answers
520 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?
4
votes
4answers
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 ...
3
votes
2answers
891 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 ...
28
votes
7answers
8k views

Why tap the brakes on take-off in fixed gear aircraft?

The Socata TB10 checklist indicates that you should touch the brakes after lift-off. I assume this is to stop the wheels from turning, but why? In a retractable gear aircraft this would make sense to ...
7
votes
2answers
575 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 ...
20
votes
4answers
5k 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.
2
votes
3answers
160 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 ...
8
votes
3answers
3k 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 ...
8
votes
1answer
400 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 ...
1
vote
1answer
1k views

Why doesn't the autobrakes and ground spoilers deploy on the A320 if the speed is below 72 knots?

I really can't understand the reason as to why Airbus has put a speed restriction of 72 knots for the activation of autobrakes and deployment of ground spoilers. Could someone explain why this has ...
7
votes
2answers
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 ...
7
votes
1answer
12k views

In an emergency, how much runway does an A320 need to stop safely?

From time to time I land at Wellington Airport in an A-320. The runway has sea at either end and is 2,081m (6,827ft) long. There's never been a problem but I find landing there a bit nerve wracking ...
4
votes
1answer
275 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 ...
6
votes
1answer
421 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 ...
5
votes
1answer
554 views

How much does pilot technique affect brake life?

Anecdotally I have heard of various things that I can do to make steel brakes last longer before they have to be replaced, and they make sense but how much does it really help? Things that I have ...
1
vote
3answers
175 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 ...
1
vote
1answer
262 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....
5
votes
1answer
224 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 ...
4
votes
2answers
376 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 ...
2
votes
1answer
104 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 ...
0
votes
2answers
967 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.
2
votes
3answers
275 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?
15
votes
4answers
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 ...
20
votes
2answers
3k views

How do aircraft brake when using skis?

Planes use skis to land on ice/snow runaway. How can the plane brake in such conditions? Friction must be limited to allow takeoff and aerodynamic braking are not the main contributors to the ...
10
votes
2answers
2k views

How does landing performance differ on water vs. ice vs. paved/grass runways?

It's a follow up from How do aircraft brake when using skis? Can someone give me data about difference between landing distance for each environment ? Paved Grass Water Snow/Ice Any aircraft is ...
5
votes
2answers
426 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 ...
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.
6
votes
2answers
3k 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 ...
30
votes
6answers
15k views

For large jets, what is the primary means of slowing down after landing?

I understand that a large(r) commercial jet slows down after landing using the following methods: Wheel brakes Reverse thrust Spoilers/flaps/airbrakes What is the effectiveness of each compared to ...
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
votes
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.
27
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 ...
-5
votes
1answer
4k views

How do multiple-disc brakes work?

Multiple disc brakes uses stators & rotors to brake? How do they work? (Source)
-1
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2answers
408 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.
40
votes
4answers
8k views

Do commercial aeroplanes use ABS to brake?

I have read that the wheel brakes on an aeroplane are by for the most efficient means of stopping it. I was wondering whether in low grip situations, such as in rain or snow, an ABS (Anti-lock Braking ...
9
votes
1answer
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?
1
vote
1answer
115 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
799 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
200 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
494 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 ...
15
votes
2answers
3k views

Why aren't the canards used as airbrakes on the Tupolev Tu-144?

The Tupolev TU-144 uses retractable canards to stabilize the aircraft while starting and landing. On this picture you can see them very well: Source: AirlineFan.com Copyright: VOLPATI It doesn't ...
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 ...
5
votes
1answer
577 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
2answers
173 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 ...
12
votes
1answer
522 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
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 ...
5
votes
1answer
128 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 ...
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 ...
10
votes
2answers
1k 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 ...
3
votes
2answers
598 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 ...