I flew back from CDG today on Airbus 330. We were headed out to take off and we had to hold short as pilot said due to length of the taxiing, the brakes had overheated and they had to let them cool. In 40 years of irregular commercial flights, this was first time experience. Does this happen often??
Pilot taxiing question
- Thread starter MrJayhawk
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Never heard that one - but with some long waits to be cleared - maybe a couple cooled without fanfare …
Well, it's likely the brakes weren't overheated<!> as much as they exceeded the temperature threshold that is required to be maintained in the case of a potential Rejected Takeoff (RTO) scenario. In this case, the Brake Temp Monitor System (BTMS) likely put up a Caution light on the Flight Deck. It is also likely the brake temps at the time of push-back were not "stone-cold" and thus had some residual heat from the previous flight (i.e., short-turn at the gate). Therefore, the taxi started with warm(er) brakes, and then with a long taxi-out and a high idle thrust (not unusual with today's high-bypass engines), which can require repetitive brake applications to maintain taxi speeds under 25 knots (speed limit), the brake temps eventually exceeded the takeoff limits, so the pilots had to hold-short and allow them to cool-down.
Pilot mentioned the RTO in message. Plane had been sitting at gate for 2 1/4 hrs so unsure if that would be short turnaround. This may or not be related but upon landing at DTW we taxi over to gate, then sat there for 10 min within 100 yds of gate. Gate was empty.
Calling @Just a civilian pilot our resident Airbus expert
Our FARP was pretty far from our maintenance hangar on Basra and we would have to stop several times during a tow to pour water on the Apache’s brakes or they would catch fire.
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No.
I have never had to wait for the brakes to cool before take off, never.
Just saw this ….will reply in greater detail late tonight.
Come on..............he left the parking brake on. You know he did.
If the brake temps exceed 300C, takeoff is prohibited in an Airbus 320 series. Reckon it’s the same in this one.
You can warm the brakes up too much by “riding” them as you taxi...that is, holding your speed steady by very light pressure.
The better technique - let the speed build, say, to 25 knots, brake smoothly to, say, 10 knots, then come completely off to let them cool.
They’re often quite warm when you exit the runway after a normal landing in a hot place with some altitude, say, LAS. Often 400-500C. A quick turn may not allow the brakes to cool sufficiently before the next taxi out. We had big fans prepositioned for the Airbus brakes in LAS.
Airbus also offers optional, integral cooling fans on 320 series airplanes just to manage brake temps.
I taxi often on one engine. Particularly when taxing in.
Partly to save fuel, partly to keep the brakes cooler.
You can warm the brakes up too much by “riding” them as you taxi...that is, holding your speed steady by very light pressure.
The better technique - let the speed build, say, to 25 knots, brake smoothly to, say, 10 knots, then come completely off to let them cool.
They’re often quite warm when you exit the runway after a normal landing in a hot place with some altitude, say, LAS. Often 400-500C. A quick turn may not allow the brakes to cool sufficiently before the next taxi out. We had big fans prepositioned for the Airbus brakes in LAS.
Airbus also offers optional, integral cooling fans on 320 series airplanes just to manage brake temps.
I taxi often on one engine. Particularly when taxing in.
Partly to save fuel, partly to keep the brakes cooler.
They don’t move with the parking brake on.
At all.
It’s not like a car.
The parking brake on an airplane simply sends full available (3,000 psi, with engines running, accumulator pressure otherwise) hydraulic pressure to the regular brakes.
What do you mean it aint like a car? It has a go pedal and a stop pedal. Or lever, whatever.
Is there an emergency brake or is the parking brake it?
How hot do they get when the plane lands?
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Sorry, got called out to cover a flight last minute ( short flight, I never do them normally….short pilots ) and just got in the hotel.
The basic answer is no, it’s not normal to have to wait for the brakes to cool before take off. I have never had to wait for them to cool before take off.
You would have to work pretty hard to heat them up to 300 Celsius ( A320 limit for take off ) on the A319/320, but you could heat them up to 300 c or higher more easily on the heavier A321 in certain situations ( some planes have brake fans ).
The only way I can see the brakes getting too hot is if it’s a long taxi route , pilot riding the brakes ( not monitoring brake temps as taxi ) and/or taxiing too fast and hard braking periodically heading out to the departure runway.
Taxiing with the wind behind the aircraft ( tailwind ) can add to the acceleration and pilot riding the brakes , made worse if taxiing with two engines due to extra thrust versus taxiing on one engine.
I taxi out single engine more than most at my company and it saves fuel ( minimal )
and makes it very hard to heat the brakes up due to less thrust pushing the aircraft.
Large differences in elevation ( 132 feet in some places at Las Vegas airport ) can cause pilots to ride the brakes also.
If you are taxiing out l you should ( do it correctly number one ) monitor the brake temperatures and be proactive if they start approaching the 300 c limit to prevent having to wait for them to cool before take off.
The 300 c limit for take off BTW is because Airbus doesn’t want a fire in the wheel well if there is hydraulic fluid leaking when the gear retracts. There is a fire risk above 300 c. Additionally, brake temps too high before take off would compromise braking in the event of a high speed rejected take off.
The basic answer is no, it’s not normal to have to wait for the brakes to cool before take off. I have never had to wait for them to cool before take off.
You would have to work pretty hard to heat them up to 300 Celsius ( A320 limit for take off ) on the A319/320, but you could heat them up to 300 c or higher more easily on the heavier A321 in certain situations ( some planes have brake fans ).
The only way I can see the brakes getting too hot is if it’s a long taxi route , pilot riding the brakes ( not monitoring brake temps as taxi ) and/or taxiing too fast and hard braking periodically heading out to the departure runway.
Taxiing with the wind behind the aircraft ( tailwind ) can add to the acceleration and pilot riding the brakes , made worse if taxiing with two engines due to extra thrust versus taxiing on one engine.
I taxi out single engine more than most at my company and it saves fuel ( minimal )
and makes it very hard to heat the brakes up due to less thrust pushing the aircraft.
Large differences in elevation ( 132 feet in some places at Las Vegas airport ) can cause pilots to ride the brakes also.
If you are taxiing out l you should ( do it correctly number one ) monitor the brake temperatures and be proactive if they start approaching the 300 c limit to prevent having to wait for them to cool before take off.
The 300 c limit for take off BTW is because Airbus doesn’t want a fire in the wheel well if there is hydraulic fluid leaking when the gear retracts. There is a fire risk above 300 c. Additionally, brake temps too high before take off would compromise braking in the event of a high speed rejected take off.
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The highest I see is around 450 c.
Land in Las Vegas, clear the runway and tailwind combined with very large elevation difference between roll out exit taxiway to gate.
Aircraft wants to accelerate fast so I shut down one of the engines ASAP after engine cooling times are reached.
I have never used airport brake fans. If I get in the cockpit ( plane just arrived late, crew change ) and the brakes are really hot in Vegas, I make sure the chocks are in and turn the park brake off to help them cool faster. After push back if still above 300 c, I taxi out on one engine and start the second engine when appropriate and they are below 300 c ( very rare to taxi out above 300 c , even in Las Vegas ) at that point in the taxi ( taxi speed, if done right, helps cool them heading to the runway ).
Due to runway construction at my base , we always land ( wide bodies get the longer parallel runway, we get the much shorter one unless we have an operational requirement for the longer runway ) on a 7000 long runway which can heat up the brakes when close to max landing weight and the runway is wet ( happened a lot this summer ). The landing calculations show only 500 feet extra runway at times ( but the calculations include a 15% margin so there is more than that when we clear the runway…..about 1000 feet ).
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I've never heard of this happening. On the Dreamliner and some newer aircraft they use carbon composite brakes requiring a re learning of braking as cc brakes can handle alot of heat.
Carbon brakes are standard on every aircraft we have, including the 757 and 767, the oldest in our fleet. They’re not that new.
I have had hot brakes in LAS - long story, when I was an FO on the A-320 involving a bleed overheat (that wasn’t a bleed overheat, but a leading edge device sensor that was getting cooked in the sun), 115F on the ramp, a quick return to gate, and brakes that weren’t cooled prior to the next taxi out, and a quick taxi out with a hot airplane.
It was not a good day. Already hot in the back - having to wait for takeoff - all while the packs (the AC compressors) could not keep up with a plane full of people on that hot, hot day.
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Was this DL 229? It's not uncommon for this particular aircraft to have hot brakes. They could have added a bit more meat to the system and avoided many of the issues but Airbus chose to offer optional cooling fans instead.
Brake heads have a temp. sensor on the body that sends temp. data to the pilots. There is a safety margin of about 200ºC between when the brakes are considered too hot to continue and when the thermal fuse blows in the wheel.
Yes it was. The pilot had said en route thst we were 3rd in line to depart so there wasnt a lot of stop and go on way out there. Taxi speed didnt seem all that fast, pretty normal. My thought at the time, and I told my wife this, if brakes are hot just from taxiing, what about when we actually land this thing? That’s what made me think when we finally landed and got to gate he had to let them cool before trying to park it.
