Questions tagged [braking]

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

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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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
22
votes
4answers
4k views

When the brakes are checked, what do the firemen actually do?

Watching this video (at 06:58 mark), this plane had just made a mayday landing, due to a bird-strike. Because of the right engine being shutdown, it was forced to land immediately, with a full load of ...
21
votes
1answer
4k views

Can the wheel brakes hold an airliner in place if its engines are at full thrust?

Are wheel brakes on most commercial jet airliners capable of holding the jet stationary on a dry surface, if all the engines are given full thrust? Could doing this be potentially unsafe or damaging ...
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.
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 ...
19
votes
3answers
11k 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 ...
18
votes
4answers
10k 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 ...
18
votes
2answers
2k views

Why do modern jetliners provide Thrust Reversers at all in their design decisions?

Let's start with the following knowns (please correct me if I am wrong about any): The braking force provided by the wheel brakes is much larger than that by the thrust reversers One is not allowed ...
17
votes
5answers
10k 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, ...
16
votes
3answers
3k views

Why is the drogue parachute jettisoned on the runway?

Why is the drogue parachute of a military plane jettisoned on the runway? Why not drag it to the parking area for safe removal, inspection, and repacking?
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 ...
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 ...
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.
14
votes
4answers
14k views

What is the advantage of combining the rudder and brake pedals in aircraft?

I've read about several aircraft having their rudder and brake pedals very close together. To me this seems confusing and prone to error. It looks easy to mistake the rudder / brake pedals and ...
14
votes
3answers
16k views

What is differential braking?

How is differential braking different from regular braking? How do you accomplish differential braking and why would you need to use it?
14
votes
1answer
3k 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 ...
13
votes
9answers
67k views

Does a plane have brakes to stop or slow down while flying?

Does a plane have brakes to stop or slow down while flying? For example, if the pilots see a large flock of birds at some distance in front of the airplane, and they want to reduce speed suddenly. ...
13
votes
3answers
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 ...
12
votes
4answers
3k views

What effect would there be if the brakes were locked at touchdown?

I'm imagining if you had a panicky passenger sitting in the right seat who had both feet firmly on the brakes while landing. Unless you had a crosswind and needed rudder as you touched down it's ...
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 ...
12
votes
1answer
788 views

What are the relative braking contributions from wheel brakes, spoilers and thrust reversers?

What is the relative contribution to braking forces in a typical large commercial aircraft from the three different devices contributing to braking after touchdown: Wheel brakes Speed brakes / ...
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 ...
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.
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 ...
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 ...
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?
9
votes
4answers
2k views

What is the effect of changing the autobrake setting after touchdown?

If an autobrake setting is chosen prior to touchdown, but after touchdown and nosewheel compression (i.e. after the autobrake has engaged) a different setting is required, is it safe to change the ...
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?
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
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 ...
8
votes
1answer
4k views

How does autobrake work?

An autobrake is a type of automatic wheel-based hydraulic brake system for advanced airplanes. The autobrake is normally enabled during takeoff and landing procedures, when the aircraft's longitudinal ...
8
votes
3answers
1k 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 ...
8
votes
1answer
403 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 ...
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 ...
7
votes
1answer
4k views

What is Brake To Vacate (BTV)?

Emirates has this feature on many of its A380s. From what I've read, the feature decreases the amount of runway an aircraft uses after landing. It also helps the aircraft achieve a certain exit way. ...
7
votes
2answers
577 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 ...
6
votes
2answers
296 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 ...
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 ...
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 ...
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? ...
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?
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 ...
5
votes
2answers
892 views

What are the pros & cons of Autobrake?

What are the advantages/disadvantages of an autobrake system? In particular I am interested in the Fokker 100 system. Have any studies been done for the F100 autobrakes and the affects that this ...
5
votes
1answer
4k views

How often are heavy aircraft brake pads changed?

How often are Boeing 747-800 and Airbus A380 aircraft brake pads changed?