airbusb0y
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VS A330 Late Undercarriage Retraction? (Video)

Mon Dec 10, 2012 8:59 pm

Came across this Virgin A330 video departing LHR. The landing gear is extended longer than usual after takeoff until ATC asks them whether there is a problem? What could be the reason? Just curious.

http://www.youtube.com/watch?v=EajYuf_F4Oo
 
waly777
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RE: VS A330 Late Undercarriage Retraction? (Video)

Mon Dec 10, 2012 9:12 pm

Hmm, looks like they forgot
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shamrock321
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RE: VS A330 Late Undercarriage Retraction? (Video)

Mon Dec 10, 2012 9:19 pm

I doubt they forgot! "Positive rate-gear up" is engrained on theses guys brains! I've seen it before, it's done for many different reasons.
 
migair54
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RE: VS A330 Late Undercarriage Retraction? (Video)

Mon Dec 10, 2012 9:21 pm

Hot Brakes.... when brakes are hot you can leave it down for a while to use the ram air for cooling.
 
tardis
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RE: VS A330 Late Undercarriage Retraction? (Video)

Mon Dec 10, 2012 9:25 pm

I agree, probably hot brakes. Do Airbus have brake cooling in the gear bays like the DC-10's did?
 
sandyb123
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RE: VS A330 Late Undercarriage Retraction? (Video)

Mon Dec 10, 2012 9:36 pm

Quoting waly777 (Reply 1):
Hmm, looks like they forgot

As ridiculous as this sounds, it does look like this would have been missed! Would there be a speed warning or undercarriage warning to the flightdeck?

Quoting migair54 (Reply 3):
Hot Brakes.... when brakes are hot you can leave it down for a while to use the ram air for cooling.

But why would you have hot brakes on the take-off roll? Even heavy taxi braking wouldn't create anything like enough heat to warrant this? IIRC SOP states that after an RTO wheel brakes have to be serviceable before a second attempt so I doubt that an RTO happened before this take-off?

I would be interested to hear what happened with ATC after the climb-hold instruction. Is there anyway of listening to the ATC?

Sandyb123
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airbusb0y
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RE: VS A330 Late Undercarriage Retraction? (Video)

Mon Dec 10, 2012 9:39 pm

Hot brakes as in the wheels spinning up due to the takeoff roll and then the pilots pressing on the brakes to stop them spinning?

[Edited 2012-12-10 13:39:57]

[Edited 2012-12-10 13:40:34]
 
rwy04lga
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RE: VS A330 Late Undercarriage Retraction? (Video)

Mon Dec 10, 2012 9:43 pm

Quoting airbusb0y (Reply 6):

Not enough heat would be generated to have to keep them down so long.
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catII
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RE: VS A330 Late Undercarriage Retraction? (Video)

Mon Dec 10, 2012 9:57 pm

Most likely the gear was left down due to an MEL'd brake. Sometimes a brake can be MEL'd and so we are required to keep the gear down longer to cool the brakes off. If its a heavy load and a lot of taxiing and you take away 1 brake... the rest of the brakes have to work harder, generating more heat.

This is most likely the case here, coming from an A330 driver who's done this procedure a few times before.

To those that think they forgot the gear. Highly doubt this. The noise alone would make it hard not to forget to bring it up, it's quite noisy with the gear down! That, plus "positive rate, gear up" is literally drilled in our heads.
 
Btblue
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RE: VS A330 Late Undercarriage Retraction? (Video)

Mon Dec 10, 2012 10:01 pm

Sounds like they forgot.

As soon as the ATC alerted them, the gear was retracted.
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migair54
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RE: VS A330 Late Undercarriage Retraction? (Video)

Mon Dec 10, 2012 10:02 pm

Quoting sandyb123 (Reply 5):
But why would you have hot brakes on the take-off roll? Even heavy taxi braking wouldn't create anything like enough heat to warrant this? IIRC SOP states that after an RTO wheel brakes have to be serviceable before a second attempt so I doubt that an RTO happened before this take-off?

Usually long taxi with stop and goes create hot brakes alarm, specially if any of the brakes is not in good condition or quite worn out, so if possible a delay on the take off or leaving the landing gear donw for a while is enough.

Quoting airbusb0y (Reply 6):
Hot brakes as in the wheels spinning up due to the takeoff roll and then the pilots pressing on the brakes to stop them spinning?

there´s no need to do, it´s automatic and in the nose wheel it has a rubber block that stop them spinning by contact because they don´t have brakes.

Quoting sandyb123 (Reply 5):
I would be interested to hear what happened with ATC after the climb-hold instruction. Is there anyway of listening to the ATC?

i think they were told to stop turning at 190 degrees, Stop the roll at 190 degrees.

Quoting sandyb123 (Reply 5):
As ridiculous as this sounds, it does look like this would have been missed! Would there be a speed warning or undercarriage warning to the flightdeck?

It´s very unlikely that pilots forgot the gear in down position during a take off, very very unlikely. In case of a engine failure that extra drag can put you in a very very dangerous situation, second segment is the most critical phase of a take off specially for twins, that´s why as soon as positive climb, Gear up.

They will have a overspeed warning when they pass the maximum speed for landing gear down, planes usually have one max speed for extending the gear, one for retracting and one to fly with the gear down and lock. In Some planes some of this speeds can be close or even the same but given the usual retraction towards the front the speed for retracting the gear is lower than the one for lowering, but not always.
 
N766UA
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RE: VS A330 Late Undercarriage Retraction? (Video)

Mon Dec 10, 2012 10:49 pm

This happens a lot with the big airbuses. As others have said, it's the brakes. Nobody *forgets* landing gear, save for the occasional 20-hour-a-year Baron jockey.
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tdscanuck
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RE: VS A330 Late Undercarriage Retraction? (Video)

Mon Dec 10, 2012 10:55 pm

Quoting sandyb123 (Reply 5):
But why would you have hot brakes on the take-off roll?

Brakes cool very very slowly on the ground; prolonged taxing with brake riding can heat up the brakes.

Quoting sandyb123 (Reply 5):
Even heavy taxi braking wouldn't create anything like enough heat to warrant this?

It's happened to me many times.

Quoting sandyb123 (Reply 5):
IIRC SOP states that after an RTO wheel brakes have to be serviceable before a second attempt so I doubt that an RTO happened before this take-off?

It doesn't matter if you had an RTO before, you can get hot brakes just driving around on the ramp if it's a long taxi.

Quoting rwy04lga (Reply 7):
Not enough heat would be generated to have to keep them down so long.

That's a workload thing...if you don't pull them up right away then you're involved in tower > departure handoff, watching for traffic, etc. There's no real problem with leaving them down until workload lightens up.

Quoting catII (Reply 8):
Most likely the gear was left down due to an MEL'd brake. Sometimes a brake can be MEL'd and so we are required to keep the gear down longer to cool the brakes off.

If a brake is on MEL the problem isn't heat, it's spin down. Without the brakes, the wheel will only spin down with bearing friction. You do not want to retract a spinning MLG wheel into the wheel well.

Tom.
 
waly777
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RE: VS A330 Late Undercarriage Retraction? (Video)

Tue Dec 11, 2012 12:31 am

Quoting btblue (Reply 9):
As soon as the ATC alerted them, the gear was retracted.

Exactly my point, whilst "gear up" is a routine procedure once a positive rate of climb is confirmed, these guys seems to have forgot for whatever reason.

If it was a case of the brakes being too hot, they would have left the gear extended a bit longer to cool and not retracted it as soon as atc questioned if there was a problem and pointed out their gear was still extended.

Certainly looks like they may have forgot.
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CCA
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RE: VS A330 Late Undercarriage Retraction? (Video)

Tue Dec 11, 2012 1:08 am

From the 747 MEL A330 is probably similar.

Quote:
One or two brakes may be deactivated by capping the brake line provided:

a. Take-off and landing performance complies with Operations Manual, both for Gear Down dispatch and for two brakes deactivated.

b. After take-off, gear remains down for two minutes before retraction

I doubt the crew forgot, I image as ATC prompted them and rather than waste ATC chatter they just said "negative standby" and probably something along the lines of that's close enough and selected the gear up.

I tell ATC with the takeoff clearance that we will be leaving the gear down to prevent ATC having to mention it, however if in a foreign country this may result in unnecessary chat so you have to pick when it's suitable.
P1 in A330, A340, A346, B742, B744, B748.
 
spacecadet
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RE: VS A330 Late Undercarriage Retraction? (Video)

Tue Dec 11, 2012 5:11 am

Quoting waly777 (Reply 13):
If it was a case of the brakes being too hot, they would have left the gear extended a bit longer to cool and not retracted it as soon as atc questioned if there was a problem and pointed out their gear was still extended.

What's more likely, that the crew "forgot" to raise the gear, or that they left it down to cool the brakes and it was a very minor coincidence that they raised the gear around the same time ATC spoke up? The former never happens, the latter happens quite frequently.

Also, listen to the pilot's reaction to ATC. He immediately says "negative" when asked if there's any problem. He doesn't take a second to think, or to check that ATC's correct, or to come up with some kind of excuse. He doesn't pause and he doesn't say "uhhhh...." or "oops!" He knows the gear's down, and it's down on purpose.

[Edited 2012-12-10 21:14:57]
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AAMDanny
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RE: VS A330 Late Undercarriage Retraction? (Video)

Tue Dec 11, 2012 9:58 am

VS's airbus fleet IIRC are not configured with a brake cooling system, LHR can have long taxi journeys too so maybe this was the reason.
 
9VSIO
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RE: VS A330 Late Undercarriage Retraction? (Video)

Tue Dec 11, 2012 10:04 am

Perhaps this belongs in tech/ops?
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peterjohns
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RE: VS A330 Late Undercarriage Retraction? (Video)

Tue Dec 11, 2012 10:12 am

Hello There
Hot brakes are the reason. On A330/340 there is a max retraction temp.- if this is succeeded the gear has to stay out. It happens very frequently - for several reasons:
- long taxi times at todays airports. The brakes are used constantly.
- High thrust output at idle pwr due to modern engines. One also can´t just turn one or two off due to the seperate/independant hydraulic systems. Plus on 340 you would need extra pwr to go around sharp turns- which is not allowed on the ramp.
- Short turnaround times. Often the brakes are still hot from the landing just an hour ago...
- Anti Ice prior T/O needs extra thrust, so also extra brake usage...

Good day to everyone!!
 
AR385
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RE: VS A330 Late Undercarriage Retraction? (Video)

Tue Dec 11, 2012 10:14 am

Quoting waly777 (Reply 13):
Exactly my point, whilst "gear up" is a routine procedure once a positive rate of climb is confirmed, these guys seems to have forgot for whatever reason.
Quoting migair54 (Reply 10):
It´s very unlikely that pilots forgot the gear in down position during a take off, very very unlikely.
Quoting btblue (Reply 9):
Sounds like they forgot.

While I will probably be flamed for this, I have this little anecdote to share:

One of my best friends, heck, I flew 10hrs to Spain for his wedding on an outrageous fare for only a weekend, because I could not get time off, is a UX pilot. A few years ago, when he was one of their 737s FOs he told me about one flight where they forgot to raise the gear. Essentially, his Captain and him were baffled that they could not accelerate as fast or to their desired speed. Afer a few checks, they THEN checked the gear, and surprise, surprise, they realized they had not raised it.

He is now a UX Captain, and I won´t tell the airliner he flies.

So I know for a fact it can happen. Was this the case here? I don´t know. But forgetting to raise the gear is a certain possibility.
 
speedbird128
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RE: VS A330 Late Undercarriage Retraction? (Video)

Tue Dec 11, 2012 10:45 am

Quoting AR385 (Reply 19):
Essentially, his Captain and him were baffled that they could not accelerate as fast or to their desired speed.

Nevermind the noise and vibration created at high speed with gear down.

Realistically, how can one not notice?
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delawareusa
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RE: VS A330 Late Undercarriage Retraction? (Video)

Tue Dec 11, 2012 12:56 pm

could have been a blown tire late in the take off roll, then gear left down to cool. Happened to me on US Airways. A330 left gear down for a few minutes, then pulled them up and flew on to LGW
 
JHCRJ700
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RE: VS A330 Late Undercarriage Retraction? (Video)

Tue Dec 11, 2012 3:55 pm

Quoting btblue (Reply 9):
Sounds like they forgot.

Read the post before yours. lol.

Quoting tdscanuck (Reply 12):
It's happened to me many times.

Is there a gauge or warning of some sort that lets you know that the brakes are hot, or is simply by experience that you can "feel" when they are hot.
RUSH
 
waly777
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RE: VS A330 Late Undercarriage Retraction? (Video)

Tue Dec 11, 2012 3:58 pm

Quoting spacecadet (Reply 15):
What's more likely, that the crew "forgot" to raise the gear, or that they left it down to cool the brakes and it was a very minor coincidence that they raised the gear around the same time ATC spoke up? The former never happens, the latter happens quite frequently

You can't possibly say the former never happens as I doubt you have been on every flight that has taken off.

Quoting spacecadet (Reply 15):
Also, listen to the pilot's reaction to ATC. He immediately says "negative" when asked if there's any problem. He doesn't take a second to think, or to check that ATC's correct, or to come up with some kind of excuse. He doesn't pause and he doesn't say "uhhhh...." or "oops!" He knows the gear's down, and it's down on purpose

Indeed he doesn't pause, but which cockpit crew will want to admit they forgot something as basic as raising the gear. I know if something like that happened, my response will be the same and will raise the gear straight away. Pausing, going "oops" etc will just be embarrassing.

For the record, I have been on a BA flight where the crew forgot to raise the gear and raised it 2 mins later. I know this because I'm close friends with the first officer of that flight.

Besides, all of this is just assumption....none of us were in that cockpit and can only guess. No human is above mistakes especially minor ones.
The test of first-rate intelligence is the ability to hold 2 opposed ideas in the mind concurrently, and still function
 
RussianJet
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RE: VS A330 Late Undercarriage Retraction? (Video)

Tue Dec 11, 2012 4:11 pm

Quoting delawareusa (Reply 21):
could have been a blown tire late in the take off roll, then gear left down to cool. Happened to me on US Airways. A330 left gear down for a few minutes, then pulled them up and flew on to LGW

But whether it was brakes, a tire or whatever other reason, why didn't he quickly reply to ATC what the issue was rather than just saying no problem and bringing the gear up immediately after? Would it really take so long and be such a distraction to say 'negative, cooling brakes' or similar?
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tdscanuck
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RE: VS A330 Late Undercarriage Retraction? (Video)

Tue Dec 11, 2012 4:19 pm

Quoting JHCRJ700 (Reply 22):
Is there a gauge or warning of some sort that lets you know that the brakes are hot, or is simply by experience that you can "feel" when they are hot.

Many modern jets (most?) have a brake temperature monitoring system...it's usually on an auxiliary EICAS/ECAM page (for Boeing/Airbus). If the brakes are too hot there will be a caution message to the crew to that effect.

Quoting RussianJet (Reply 24):
But whether it was brakes, a tire or whatever other reason, why didn't he quickly reply to ATC what the issue was rather than just saying no problem and bringing the gear up immediately after?

There's no reason to reply to ATC with what the issue was unless they need ATC's help. That's just cluttering the radio.

Quoting RussianJet (Reply 24):
Would it really take so long and be such a distraction to say 'negative, cooling brakes' or similar?

If they still needed the gear down, they probably would have said that. Based on the fact that they pulled it up, they obviously didn't need it down any longer and there's no value in replying to ATC with that information.

Although I'm sure it's possible for a crew to forget to raise the gear, it's really uncommon. Leaving it down for brake cooling or tire spin-down is much more common. The most likely scenario, given the limited evidence, is that the crew left the gear down on purpose and then went on with their normal initial climb-out workload...when ATC prompted them, they looked at whatever indicators they needed to look at (brake temp if it was cooling, time if it was spin down), saw that they'd passed the necessary threshold and pulled the gear up. Initial climb-out is busy, you don't have enough time to have one crew member fixated on the brake cooling screen or the clock waiting for the precise second that the gear is ready to come up. Having the gear down does no harm (assuming all engines operating) until you get into the acceleration phase so there's no particular reason to be monitoring it closely.

Tom.
 
bueb0g
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RE: VS A330 Late Undercarriage Retraction? (Video)

Tue Dec 11, 2012 4:46 pm

Quoting waly777 (Reply 1):
Hmm, looks like they forgot

No it doesn't

Quoting btblue (Reply 9):
Sounds like they forgot.

No it doesn't

Quoting Speedbird128 (Reply 20):
Realistically, how can one not notice?

Exactly, you can't.

Quoting waly777 (Reply 23):
Indeed he doesn't pause, but which cockpit crew will want to admit they forgot something as basic as raising the gear.

The point is there is no pause or surprise - he wasn't alerted to the situation by ATC, he already knew it was down.

Quoting waly777 (Reply 23):
For the record, I have been on a BA flight where the crew forgot to raise the gear and raised it 2 mins later. I know this because I'm close friends with the first officer of that flight.

I call BS.
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waly777
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RE: VS A330 Late Undercarriage Retraction? (Video)

Tue Dec 11, 2012 5:12 pm

Quoting bueb0g (Reply 26):
I call BS.

Makes no difference to me.

Base point, everything on this thread is an assumption except a member of the crew is on Anet to verify.
The test of first-rate intelligence is the ability to hold 2 opposed ideas in the mind concurrently, and still function
 
brilondon
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RE: VS A330 Late Undercarriage Retraction? (Video)

Tue Dec 11, 2012 6:10 pm

Quoting btblue (Reply 9):
Sounds like they forgot.

As soon as the ATC alerted them, the gear was retracted.

Why would they not tell ATC about the hot breaks? To me it seems like they just forgot.
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JBirdAV8r
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RE: VS A330 Late Undercarriage Retraction? (Video)

Tue Dec 11, 2012 6:25 pm

Quoting catII (Reply 8):
Most likely the gear was left down due to an MEL'd brake. Sometimes a brake can be MEL'd and so we are required to keep the gear down longer to cool the brakes off. If its a heavy load and a lot of taxiing and you take away 1 brake... the rest of the brakes have to work harder, generating more heat.

This.   

Quoting waly777 (Reply 13):
Exactly my point, whilst "gear up" is a routine procedure once a positive rate of climb is confirmed, these guys seems to have forgot for whatever reason.

If it was a case of the brakes being too hot, they would have left the gear extended a bit longer to cool and not retracted it as soon as atc questioned if there was a problem and pointed out their gear was still extended.

Certainly looks like they may have forgot.

Um...no.

Quoting brilondon (Reply 28):
Why would they not tell ATC about the hot breaks? To me it seems like they just forgot.

Because ATC doesn't care about hot brakes or an MEL'd brake. We're not required to tell them anything.

Forgetting to put the gear up just doesn't happen in Part 121 transport ops. Never. The procedure is like a rhythm, repeated exactly the same way, every flight, every day, in many thousands of airplanes across the globe.

Positive rate. Gear up. Gear up.
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tdscanuck
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RE: VS A330 Late Undercarriage Retraction? (Video)

Tue Dec 11, 2012 6:53 pm

Quoting brilondon (Reply 28):
Why would they not tell ATC about the hot breaks?

Because ATC doesn't need to know, doesn't care, and actively discourages people from taking up radio time for things that don't have to do with vectoring airplanes. ATC would prefer that you *don't* tell them because that's radio time they could be talking to airplanes to do their job. ATC knows that if the flight crew needs their help, the flight crew will ask for it. If they have time, ATC will try to be helpful by doing things like pointing out to the pilots that their gear is down...if it was a mistake (one I've never seen in Part 121 ops but it's possible) then the crew will raise the gear. If it wasn't a mistake the crew will check to see if whatever reason they kept the gear down for is expired and, if it has, they'll raise the gear. If the reason hasn't expired the flight crew may just say "Thank you" to ATC or they may explain *if* they need to keep the gear down longer but there is absolutely no requirement to tell ATC that.

Tom.
 
Wisdom
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RE: VS A330 Late Undercarriage Retraction? (Video)

Tue Dec 11, 2012 8:35 pm

It was in October in the UK, so about 15°C temperatures, Virgin's widebodies have long turn-around times, at an airport with a long runway. So brakes start off very cold, taxiing won't bring the dials anywhere near the temperature that one could call hot.
It's not in 15 additional seconds in ram air that you're going to make a difference, ram air actually creates a negative lateral pressure (similar to air going over and under the wing), so most of the ram air won't reach the brake discs directly but rather hit the casing and cool progressively. It works better than with static air but not much, hence the popularity of brake fans which blow air laterally, much more efficiently.

So it's unlikely that the brakes were anywhere near hot but it's possible.

I think that given the unlikelihood that they forgot them, they may have had other priorities to deal with.
The immediate standby call and the unwillingly extended turn interrupted by ATC reminding them to stop the turn at 190, point to the fact that they were running behind but not because of a major issue, given the prompt responses and the negative.
It may for instance have been that they received a master caution during the take-off and were considering its repercussions and trying to enhance their situational awareness during a less usual East-bound EGLL MID departure.
It could also be a MEL'ed brake.

The aircraft was headed to ORD (callsign), the mx hop is thus ruled out.
 
keta
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RE: VS A330 Late Undercarriage Retraction? (Video)

Tue Dec 11, 2012 9:03 pm

Quoting peterjohns (Reply 18):
Hot brakes are the reason. On A330/340 there is a max retraction temp.- if this is succeeded the gear has to stay out.

Could it happen that a takeoff has to be postponed because of hot brakes, if the constraint is tight in the second segment?
Where there's a will, there's a way
 
peterjohns
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RE: VS A330 Late Undercarriage Retraction? (Video)

Tue Dec 11, 2012 11:50 pm

Quoting keta (Reply 32):
Could it happen that a takeoff has to be postponed because of hot brakes, if the constraint is tight in the second segment?

Well not really. The brakes can cool off quickly once in the air. There are other factors as well, which would call for a fast departure( economical issues) . The Brake Temp does not interfere with the brake performance in case of aborted T/O - then the brakes are u/s anyway...!
 
Horstroad
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RE: VS A330 Late Undercarriage Retraction? (Video)

Wed Dec 12, 2012 12:05 am

I guess it´s because of a MEL'd brake as said before.

all main wheels need to stop during/prior to retraction. normally when the retract cylinder gets powered, all brakes get powered as well to stop the wheels spinning. when one brake is inop you have to wait for the wheel to stop by its own before you retract the landing gear.

Quoting CCA (Reply 14):
b. After take-off, gear remains down for two minutes before retraction

I don't think it was because of overheating. two minutes are not enough to cool down the brakes sufficiently unless they where just above the limit
 
AR385
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RE: VS A330 Late Undercarriage Retraction? (Video)

Wed Dec 12, 2012 12:28 am

Quoting JBirdAV8r (Reply 29):
The procedure is like a rhythm, repeated exactly the same way, every flight, every day, in many thousands of airplanes across the globe.
Quoting JBirdAV8r (Reply 29):
Forgetting to put the gear up just doesn't happen in Part 121 transport ops. Never.

Exactly. Just like forgetting to lower the flaps for take off. Oh wait...
  
 
Wisdom
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RE: VS A330 Late Undercarriage Retraction? (Video)

Wed Dec 12, 2012 1:15 am

Quoting peterjohns (Reply 33):
The Brake Temp does not interfere with the brake performance in case of aborted T/O - then the brakes are u/s anyway...!

The initial brake temp does affect RTO performance. As a rule of thumb, the brakes need to be less than 150°C to be able to perform a proper RTO at V1 (or higher).
If you start your take-off run with very hot brakes, and reject at V1, your stopping distance will be longer and you may risk to have a brake failure.
Braking is about converting kinetic/movement energy into heat. If you start with something that's already hot, it will absorb the heat slower and as you continue braking, it will absorb heat slower and slower until it reaches catastrophic failure and disintegrates.

RTO is not always equal to U/S brakes, it depends on how new the brake packs are, at what you speed you reject, what weight you were carrying, the outside temperature and what brake temperature you reach.

Quoting peterjohns (Reply 33):
Well not really. The brakes can cool off quickly once in the air. There are other factors as well, which would call for a fast departure( economical issues) .

Sorry, I have to contradict. Ram air (or the static air that the airplane flies into) does not cool the brakes fast at all, see my explanation a few posts earlier. In 15 seconds like in this video, the temperature would only drop around 2-10°C (depending on temperature differential). That's pretty insignificant when your brakes are between 150-300°C.
Longhaul flights don't leave for a fast departure. A LHR-ORD would take 45 minutes to refuel alone.
Typical turn-around time for an A330 is 3 hours, which gives the brakes enough time to cool down.





[Edited 2012-12-11 17:21:36]

[Edited 2012-12-11 17:25:29]
 
tdscanuck
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RE: VS A330 Late Undercarriage Retraction? (Video)

Wed Dec 12, 2012 1:57 am

Quoting keta (Reply 32):
Could it happen that a takeoff has to be postponed because of hot brakes

Yes. If the brakes are too hot before takeoff you don't have enough capacity left to do an RTO if required.

Quoting peterjohns (Reply 33):
The Brake Temp does not interfere with the brake performance in case of aborted T/O - then the brakes are u/s anyway...!

Yes, it does. The brakes' ability to absorb kinetic energy depends on how hot they already are. If they're already hot, they may not have enough capacity left, leading to failure prior to achieving their intended purpose of stopping the aircraft.

Quoting Wisdom (Reply 36):
If you start with something that's already hot, it will absorb the heat slower and as you continue braking, it will absorb heat slower and slower until it reaches catastrophic failure and disintegrates.

The problem isn't that it absorbs heat slower...the rate of heat absorption just relates to torque and speed, not current temperture. Heat goes into the brakes via friction, not direct heat transfer, so the temperature differential doesn't matter for rate. The problem with starting at a high temperature is that you've already used up some of the brakes' thermal capacity, leaving less available to use for braking in the event of an RTO. The brakes can only absorb a finite amount of kinetic energy before they stop being brakes.

Quoting Wisdom (Reply 36):
Longhaul flights don't leave for a fast departure. A LHR-ORD would take 45 minutes to refuel alone.
Typical turn-around time for an A330 is 3 hours, which gives the brakes enough time to cool down.

If they have hot brakes, it wouldn't be because of the turn, it would be because of a prolonged taxi prior to takeoff.

Tom.
 
peterjohns
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RE: VS A330 Late Undercarriage Retraction? (Video)

Wed Dec 12, 2012 10:46 am

Quoting tdscanuck (Reply 37):
Yes, it does. The brakes' ability to absorb kinetic energy depends on how hot they already are. If they're already hot, they may not have enough capacity left, leading to failure prior to achieving their intended purpose of stopping the aircraft.

Hi there
That might be right for car brakes, but the modern stack carbon brakes actually brake even better when hot!!
The carbon/carbon composite is perfectly adapted to the friction, maintaining a constant level of efficiency whether hot or cold, at both low and high speeds. Its absorption capacity is between two and three times greater than that of steel discs.

In my post earlier I was referring to the T/O performance that doesn´t change, rather than the brake performance. If you really have to abort at a heavy load and near V1, you are going to ruin the undercarriage anyway. ( Fire, burst tires, rims..) I have actually seen it happen- the fire appeared 15min after landing- the fire brigade was just waiting, so no extra damage was done

Quoting Wisdom (Reply 36):
Typical turn-around time for an A330 is 3 hours, which gives the brakes enough time to cool down.

Last time I pushed back on A330 Transatlantic out of FRA, the brakes were still at the limit as the engines were turned on , and the temp had to be carefully observed. It was OK for retracting after departure though. Turnaround in FRA is less then 3 hrs, correction, CAN be less then 3 Hrs!!
 
 
sixtyseven
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RE: VS A330 Late Undercarriage Retraction? (Video)

Wed Dec 12, 2012 10:57 am

Someone said something about an MEL. They are absolutely right.


You have a deactivated brake- they call it capped in the Boeing world. Could be due to a leak, anti-skid inop- many reasons. One of the operational procedures is to leave the gear down for 2 minutes after takeoff to allow for that wheel to spin down. The Mains on the 767 get stopped via a very short brake application. The nose wheels stop when they come in contact with the rub plate in the nose gear bay.

Anyways a wheel spinning at 160 kts can cause a lot of heat build-up once in the well.

There are other considerations as well. Hot brakes were mentioned, In winter you can leave the gear down to blow any built up debris off that accrued during taxi on contaminated surfaces.

It's funny this thread is here. I had the very same thing happen departing YYZ about a year ago and ATC asked the same question.
Stand-by for new ATIS message......
 
peterjohns
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RE: VS A330 Late Undercarriage Retraction? (Video)

Wed Dec 12, 2012 1:46 pm

Quoting SixtySeven (Reply 39):
It's funny this thread is here. I had the very same thing happen departing YYZ about a year ago and ATC asked the same question.

See- that´s what we ATC guys are there for. If nobody looks after the Pilots and tell them what to do, they tend to do all sort of funny things... 
 
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longhauler
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RE: VS A330 Late Undercarriage Retraction? (Video)

Wed Dec 12, 2012 2:11 pm

Quoting AR385 (Reply 35):
Exactly. Just like forgetting to lower the flaps for take off. Oh wait...

Actually they are not as alike as you may think. Retracting gear on take-off is almost rote, as many on here have stated. Positive rate ... gear up.

Even if you had a distraction during take-off like a Master Warning or Master Caution, you likely would still retract the gear. The only Master Caution that would stop one from retracting the gear is "Brakes Hot" when one brake is above 300C. That warning is inhibited from 80 Kts to lift-off, so if one had hot brakes during take-off, that is when you would get the warning.

While safety might dictate otherwise, lowing the flaps for take-off is not rote. In fact if you look at the major accidents where this did happen, like the Delta B727 and the Northwest MD-80, there were so many other factors it made it a classic Reason Swiss Cheese occurrence.

I know you meant it in jest, but really the two are quite different.
Just because I stopped arguing, doesn't mean I think you are right. It just means I gave up!
 
sixtyseven
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RE: VS A330 Late Undercarriage Retraction? (Video)

Wed Dec 12, 2012 3:28 pm

Quoting peterjohns (Reply 40):
See- that´s what we ATC guys are there for. If nobody looks after the Pilots and tell them what to do, they tend to do all sort of funny things... 

Yes Peter! Always a good idea to keep at least one eye on us pilots at all times!!

Despite the good natured rivalry we pilots and ATC types are always going the extra mile to keep each other out of the glue. Those quiet moments on the radio? We pilots know you've fallen asleep. We just ask in such a way to not draw any attention to the matter and get you guys in trouble!!! "Radio check?"

LOL!!!!!
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peterjohns
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RE: VS A330 Late Undercarriage Retraction? (Video)

Wed Dec 12, 2012 4:54 pm

Quoting SixtySeven (Reply 42):
We pilots know you've fallen asleep.

Ha Ha- you can´t get me on that one- may I remind you of Oct 21st 09 , NWA 188 to Minneapolis...
  
 
AR385
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RE: VS A330 Late Undercarriage Retraction? (Video)

Wed Dec 12, 2012 5:01 pm

Quoting longhauler (Reply 41):
Actually they are not as alike as you may think. Retracting gear on take-off is almost rote, as many on here have stated. Positive rate ... gear up.

Even if you had a distraction during take-off like a Master Warning or Master Caution, you likely would still retract the gear. The only Master Caution that would stop one from retracting the gear is "Brakes Hot" when one brake is above 300C. That warning is inhibited from 80 Kts to lift-off, so if one had hot brakes during take-off, that is when you would get the warning.

While safety might dictate otherwise, lowing the flaps for take-off is not rote. In fact if you look at the major accidents where this did happen, like the Delta B727 and the Northwest MD-80, there were so many other factors it made it a classic Reason Swiss Cheese occurrence.

I know you meant it in jest, but really the two are quite different.

You are the expert in the subject, of course, and I won´t be so arrogant as to argue with you. I understand what you are saying, and the purpose of my post was just to point out (true, in jest) that you just can´t say "NEVER" with such certtainty. It´s a fact that sometimes the gear has been left down. I am sure it happens so rarely that capturing something like this in video is a more remote possibility than cathing other mistakes. I am also not saying that it was the case here. But saying "Never" I think is too much of a stretch.
 
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zeke
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RE: VS A330 Late Undercarriage Retraction? (Video)

Wed Dec 12, 2012 5:14 pm

The reason for leaving the gear down like this is normally for a deactivated brake. We leave the gear down to let the wheels spin down so they are not rotating when retracted.

Normally on gear retraction the system automatically applies the brakes to the mains, so the gyroscopic forces of the large heavy spinning mass the wheel is no longer there. If one of the brakes is deactivated, we leave the gear down so they stop rotating. The MEL reference is 32-42-01A. The nose gear does not retract out of the spinning plane, it has a small brake inside the nose gear bay.

The MEL says after takeoff, all engines operating leave the gear down for 2 minutes to allow the wheels to spin down, with an engine failure to retract the gear.

One cannot forget the gear, the air noise in the cockpit with them down is considerable.
We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
 
Norcal773
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RE: VS A330 Late Undercarriage Retraction? (Video)

Wed Dec 12, 2012 5:29 pm

Quoting waly777 (Reply 1):
Hmm, looks like they forgot
Quoting btblue (Reply 9):
Sounds like they forgot.

As soon as the ATC alerted them, the gear was retracted.
Quoting waly777 (Reply 13):
Certainly looks like they may have forgot.
Quoting waly777 (Reply 13):
Certainly looks like they may have forgot.

This is the problem with A.Net today. We have A330 pilots here who state over and over again what the reason for leaving it down is and then we have armchair pilots claiming no, the crew forgot to pull the gear up! Really people? You just don't 'forget' to pull the gear up unless you were asleep on takeoff...period!

Quoting bueb0g (Reply 26):
I call BS.

I concur!
If you're going through hell, keep going
 
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longhauler
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RE: VS A330 Late Undercarriage Retraction? (Video)

Wed Dec 12, 2012 5:33 pm

Quoting AR385 (Reply 44):
But saying "Never" I think is too much of a stretch.

I agree with you completely. Never is a very powerful word. (I am not the one that said "never".)
It is more like, "There but for the grace of God .... ".

I remember years ago when flying an A321 into TPA we had hot brakes during the taxi out, which is common in the A321 in warm weather. Not restrictive (ie. over 300C) just hot, somewhere around 250C or so. As neither terrain nor weight was a factor, we elected to keep the gear down for cooling. Understand though, it would have perfectly acceptable to retract them had we needed.

A few things struck me:

1) Three different people told us our gear was still down! Tower, the next aircraft in line for takeoff, then Terminal, after tower relayed the message! (We took off to the south, and were abeam the airport again heading north climbing through around 4000', I guess Tower was still watching us)

2) The noise in the cockpit was surprising, (as Zeke above states), almost to the point of being distracting!

3) It took almost 5 minutes to cool the brakes from 250C to 100C!

I wont say never, but honestly, I can't imagine someone forgetting the gear.
Just because I stopped arguing, doesn't mean I think you are right. It just means I gave up!
 
tdscanuck
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RE: VS A330 Late Undercarriage Retraction? (Video)

Wed Dec 12, 2012 5:40 pm

Quoting peterjohns (Reply 38):
Quoting tdscanuck (Reply 37):
Yes, it does. The brakes' ability to absorb kinetic energy depends on how hot they already are. If they're already hot, they may not have enough capacity left, leading to failure prior to achieving their intended purpose of stopping the aircraft.

Hi there
That might be right for car brakes, but the modern stack carbon brakes actually brake even better when hot!!

There is a difference between how well they brake (how fast they can decelerate the aircraft, which is how much torque the brake can apply) and braking energy (how much energy they can absorb). Modern carbon brakes, as you note, have better braking torque when hot...they don't fade with heat. However, they still have finite thermal capacity that's somewhat used up when they're already hot. As a result, both carbon and steel brakes may not be able to successfully execute an RTO if they start out hot because they don't have enough thermal capacity left to accept the kinetic energy from the aircraft.

Tom.
 
JBirdAV8r
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RE: VS A330 Late Undercarriage Retraction? (Video)

Wed Dec 12, 2012 5:46 pm

Quoting AR385 (Reply 35):
Exactly. Just like forgetting to lower the flaps for take off. Oh wait...

I thought it would be obvious that "never" meant "statistically insignificant chance." However, since the game of semantics is quite popular on A.net, I should have been more clear. My apologies.

Of course you can never say "never" as an absolute, but the statistics speak for themselves. How many scheduled air carriers have incidents where they land gear up because they forgot the gear? And I'd argue it's much easier to forget to put the gear down than it is to remember to put it up.

As for flaps, it's also much easier to forget to set them, or set them improperly, than it is to forget to pull the gear up.

I know it's probably hard to understand if you don't spend your days flying transport-category aircraft. As opposed to the other phases of operation, takeoffs are very dynamic. Both crewmembers are very focused on what the airplane is doing, and the events happen exactly the same way 99.99999% of time. The non-flying pilot will call V1, Rotate. The flying pilot pulls back, the nose rises into the air. In the airplane I fly, you can hear the "clunk" as the nose wheel strut falls into its fully extended position. As that happens, the non-flying pilot is closely watching the instruments, looking for a positive rate/trend on the vertcal speed indicator. When he sees it, he calls "Positive rate." The conditioned response to that from the flying pilot in all transport category aircraft is "Gear up." It's so ingrained into our minds, because it happens exactly the same way every time. Then we check it again with the After Takeoff checklist. It's really one of the few things I can think of that does happen with such little varation each time.

Depending on traffic flow, type of approach, ATC request, and other factors, we put the gear out at different times, and sometimes with different flap configurations. And depending on whether or not we utilize a delayed engine start, long taxi, complex instructions, de/anti-ice, etc., we put the flaps out at different times as well. You might be surprised with the variations there.

Quoting SixtySeven (Reply 42):
Despite the good natured rivalry we pilots and ATC types are always going the extra mile to keep each other out of the glue. Those quiet moments on the radio? We pilots know you've fallen asleep. We just ask in such a way to not draw any attention to the matter and get you guys in trouble!!! "Radio check?"

And then they respond with the old standby...."Sorry, I was on a landline."  
I got my head checked--by a jumbo jet