737 and A320 hot brakes on short turnarounds

Posted by hotdog_dachshund@reddit | aviation | View on Reddit | 32 comments

With many low cost carriers scheduling 45 minute turnarounds, how are these narrowbody brakes designed so that they can be used after landing in a rejected takeoff on the next leg?

I remember seeing a lot of jets having cooldown periods (forgive me if I’m not using the correct term) before brakes can be used again. I saw an A350 needed 85 minutes once.

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Punkrawk78@reddit

The 737 (at my company anyway) doesn’t have a minimum turnaround time, unless you exceed the maximum quick turnaround weight on landing, which would be indicated when you request landing data for the current conditions. This isn’t too common here in the US except at high density altitude (ie Denver) or when landing with a tailwind. You can generally avoid hitting MQTW by landing flaps 40 instead of 30, though not always of course. But we also don’t have brake temp monitors, so if you ride the brakes during taxi after landing and heat them excessively, 🤷‍♂️

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unique_usemame@reddit

can the long runways in DEN help in some way?

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1046737@reddit

Yes, you can use a lower auto brake setting which means the thrust reversers are active for longer, which means less energy is absorbed by the brakes. It's not a massive difference though.

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Difficult_Camel_1119@reddit

Ryanair has planned 25min turnaround for their 737. afaik, they mainly use the reverser to break and try to use minimum breaks

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Tomcat286@reddit

We have a short runway with lots of 737 and 320 family operating with 25 minute turnarounds. Airbus have cooling fans built in, very rarely they need 5 extra minutes while taxiing out. Operating the fans near on on stand is a severe health risk for apron workers. 737 rarely need a big external fan for cooling which is provided by our fire brigade.

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Spiritual_Ad5511@reddit

Fun fact Spirit removed the brake fans on most of their Airbus.

Their pilots are the best at brake temp management lol

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DashTrash21@reddit

Way more of an issue on the Airbus than the Boeing

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av8geek@reddit

Airbus has flimsy, overworked, light brakes.

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apeceep@reddit

Do you mean "more fuel efficient brakes"? No extra weight to carry and it doesn't seem to be a real issue.

As the saying goes: "Anyone can engineer a bridge which hold but only a good engineer can design a bridge which just barely holds"

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sneijder@reddit

Try 25 minutes on B737 in Europe, that’s the MGT for Ryanair.

Some operators turn on the brake fans on A320 family, Im happy for staff to leave the ramp for 5 minutes if it starts kicking out dust (…carcinogenic nano-particles) I’ll take a delay all day long, happens 2-3 times a year with two specific operators.

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Apprehensive_Cost937@reddit

You can use higher flap setting (lower approach and touchdown speed = less energy for brakes to absorb), and full reverse thrust (helps slow the aircraft, so brakes have to work less), and plan to vacate the runway at a later exit. All of this will help keep the brakes cooler.

It's rarely an issue, if you plan ahead, even with something like a 30 min turnaround.

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montague68@reddit

We've never had hot brake issues on the 737s. 767s we did, usually in Miami by pilots slamming the brakes trying to make the first turnoff instead of going all the way down and taxiing back. Lots of popped tires until we could get them to cut it out.

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Ancient_Juice_1127@reddit

On the 73 its more an issue at high-hot type airports (DEN). Sometimes it can be mitigated with higher flaps setting (40).

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quackquack54321@reddit

Airline pilots don’t care about their aircraft. It’s just a tool. So many times I’ve been on one and they just smoke the brakes. The plane I fly used to be an airliner and has brake fans. While we don’t try and make the first exit (most of us anyway), we do very quick turns - like 15 minutes. 99% of the time the brake temps easily get below max takeoff temps. 45 minutes is a LONG time, and it’s rare any airliner goes from landing brake application to takeoff in less than 45 minutes. While the brakes may not be ambient temps, they would certainly be below max takeoff temps.

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schrutesanjunabeets@reddit

They delay the next flight if they need to cool the brakes down. There is no special "I can cool these brakes faster" design.

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lt_dt@reddit

A320s have brake fans. On other aircraft, they go Above and Beyond to get them cooled using portable fans.

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dubvee16@reddit

Its an option on purchase. Many do not.

Further its very rare to get the brakes so hot they wont cool in time for a turn. Hot ambient temperature and thin air usually. Miami and Dallas usually wont do it, but Vegas can.

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scibust@reddit

Who needs brake fans when your main landing gear wheel hub caps stick out into the cold airflow in cruise.

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Academic_Patient@reddit

I think the case they are talking about where it can be an issue is when you land, use the brakes so they heat up, then go to takeoff but need to do a RTO where you need brakes that aren't still burning hot and haven't benefited from the cold airflow in air.

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scibust@reddit

I’m just pointing to the case where there are many short legs in a trip for this half assed joke

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MaleficentCoconut594@reddit

Also depends on how hard you use the brakes. They may not get that hot where 45min is plenty of time

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nguyenm@reddit

On A320s with the brake fan option, just turn it on if there's a green band/arc over it (over 100C). If brake fan inop or not installed, maximum brake temperature prior to next takeoff is 300C according to the Limitations section.

Depending on load and ops requirements, I often see brakes around 350C to near (but not at) 400C after a routine landing. After 45 minutes, even without brake fans I think it'll be alright as that's still plenty of time still.

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Go_Loud762@reddit

"used after landing in a rejected takeoff on the next leg"

WTF are you talking about?

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hotdog_dachshund@reddit (OP)

edited. Sorry for the confusion

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Go_Loud762@reddit

Some planes have optional brake fans to help cool the brakes. Many don't, but the smart people know how to plan the turns so that isn't a factor.

I fly the A320/321 and I can't remember the last time I had to look at the brake cooling chart to see if we could takeoff.

Basically, it is a non-issue.

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oxfordfreestyl@reddit

You could have led with this comment instead of your other so you didn't come off like a total dick.

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armspawn@reddit

I remember when I flew it occasionally we’d have to leave the gear down on departure for a few minutes after a quick turn, especially in Denver.

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comptiger5000@reddit

How long they need to cool depends on how hot they got from the previous landing. Roll further down the runway when landing on a longer runway, use more reverse, and the brakes stay cooler. A320s also have an option for brake cooling fans to help with short turnarounds.

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