QANTAS747-438 From United States of America, joined Jan 2001, 1807 posts, RR: 2 Posted (6 months 1 week 2 days 21 hours ago) and read 32084 times:
Tonight at LAX, DEC 9 at 1045p, a QF A380 was going down 24L when it suddenly slammed on the brakes and stopped right around T3 or TBIT. It appeared to be going pretty fast when it stopped. It then sat on 24L for about 5 minutes before taxiing off the runway and back to the gate under its own power. Anyone know what happened? Or why it had to slam on the brakes so quickly with much more runway to go?
My posts/replies are strictly my opinion and not that of any company, organization, or Southwest Airlines.
jonnyclark From United Kingdom, joined Feb 2011, 98 posts, RR: 0 Reply 7, posted (6 months 1 week 2 days 10 hours ago) and read 19493 times:
It could have only been doing around 80kts if it rejected for Hydraulics, (using the 737-800 for that speed margin - just before anyone jumps on my figures) however, with that amount of momentum to stop, I bet it must have felt pretty intense. After 80-90kts, usually the rule is to continue with the roll, as Hydraulics aren't sensed as a major failure. It can actually be more detrimental to stop the aircraft as the braking can cause damage to the wheels. They probably stayed for 5 mins to let the brakes cool down before taxiing off.
I am surprised they didn't manual break though, as if it was around TBIT they still would have time and distance to slow the aircraft down without putting such strain on the break discs.
tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 81 Reply 8, posted (6 months 1 week 2 days 9 hours ago) and read 18258 times:
Quoting jonnyclark (Reply 12): I am surprised they didn't manual break though, as if it was around TBIT they still would have time and distance to slow the aircraft down without putting such strain on the break discs.
Autobrakes. When you pull the thrust levers to idle they come on full power (and the spoilers come up). If they were only going 80 knots, they would have stopped in a big hurry with full braking so there may not have been much time to get onto manual brakes.
jonnyclark From United Kingdom, joined Feb 2011, 98 posts, RR: 0 Reply 9, posted (6 months 1 week 2 days 8 hours ago) and read 17631 times:
true... but even a small tap on the brakes with more pressure than the autobrakes (which you should be guarding on a take off) should in theory cancel the autobrakes (which should be a natural reaction). (Again, i've only got experience on the Boeing, not the scarebus)
B777LRF From Luxembourg, joined Nov 2008, 1015 posts, RR: 3 Reply 10, posted (6 months 1 week 2 days 8 hours ago) and read 17122 times:
How are you going to cancel the autobrakes by applying "more pressure", when in RTO setting the brakes are already delivering maximum performance? Turning the autobrake selector to "off" is, to my knowledge, the only way of cancelling RTO. But I don't know what the QF SOP says about these situations, and it's been too long to remember what the book I flew to used to say.
As for not stopping for hydraulic failures above 80, while generally speaking true, very much depends. If the skipper finds a particular failure may compromise the ability to fly he can always call "stop". In really serious cases even after V1. Again, I don't know what the QF procedures are; perhaps they do stop for certain hydraulic failure scenarios on the A380 all the way up to V1. Then again, in this particular situation they could still have been below 80. Unless you were on the flight deck, spoke to the crew or has access to the FQMS there's no way of knowing.
But, above all, why is something as mundane (relatively speaking, I know it's rather stressful for the passengers and comes with some extra work for flight and ground crews) as an RTO even deemed to be newsworthy? Surely, with 4 years of airline operations under its' belt, the A380 no longer ought to command a thread every time it throws a minor operational wobbly. It's hardly as if it decided it was too fat and discharged spare parts down on terra firma, now is it?
[Edited 2012-12-10 12:50:44]
From receips and radials over straight pipes to big fans - been there, done that, got the hearing defects to prove
Fuling From Australia, joined Apr 2011, 187 posts, RR: 0 Reply 11, posted (6 months 1 week 2 days 8 hours ago) and read 16281 times:
Quoting B777LRF (Reply 15): A380 no longer ought to command a thread every time it throws a minor operational wobbly
I think a lot of attention is still given to the A380 because it is a relatively new aircraft, and is quite different to anything ever built, that this is why we are still getting threads about minor operational wobblies.
tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 81 Reply 13, posted (6 months 1 week 2 days 2 hours ago) and read 9647 times:
Quoting Norcal773 (Reply 27): I am no A380 pilot but I remember learning in flight school ages ago when I thought I wanted to be a pilot that V1 is committing you're getting off the ground, no matter what happens.
Quoting jonnyclark (Reply 22): I'm not sure if you are a commercial pilot, or your level of experience, so forgive my return on this, but that is taught from pretty much day 1 of groundschool to continue the roll at V1 regardless.
The guidance is continue after V1 *unless you believe the aircraft cannot fly*. A runway overrun may still be safer than taking an aircraft into the sky that isn't capable of staying there. Pilots are not blindly instructed to continue all takeoffs after V1, but it's a pretty tricky thing to assess the situation, determine the aircraft is safer on the ground, and reject all between V1 and rotation.
Norcal773 From United States of America, joined Feb 2007, 1286 posts, RR: 12 Reply 16, posted (6 months 1 week 2 days 1 hour ago) and read 8527 times:
Quoting tdscanuck (Reply 14): The guidance is continue after V1 *unless you believe the aircraft cannot fly*. A runway overrun may still be safer than taking an aircraft into the sky that isn't capable of staying there. Pilots are not blindly instructed to continue all takeoffs after V1, but it's a pretty tricky thing to assess the situation, determine the aircraft is safer on the ground, and reject all between V1 and rotation.
Putting it that way, of course! Well-put Tom. Not to mention it'd be a decision made in a split-second.
Mcoov From United States of America, joined Jul 2011, 113 posts, RR: 1 Reply 17, posted (6 months 1 week 2 days 1 hour ago) and read 8269 times:
Quoting B777LRF (Reply 11):
How are you going to cancel the autobrakes by applying "more pressure", when in RTO setting the brakes are already delivering maximum performance?
I believe he meant applying a bit of pressure to the brake pedal. This should tell the computer that the pilot is now going to make the brake application instead of the automated systems. However, given the different philosophies of A and B about who is ultimately in control of the airplane, that may not work for an Airbus.
PassedV1 From United States of America, joined Oct 2012, 156 posts, RR: 0 Reply 18, posted (6 months 1 week 2 days ago) and read 7920 times:
Quoting CosmicCruiser (Reply 16): I guess it depends on the jet. We are taught to "arm" the A/B for T/O but if we reject it's max MANUAL brakes to a complete stop
Right, but the autorakes were armed when the thrust levers were brught up to take-off power and the aircraft reached the requisite speed...they were then activated when the thrust levers were brought back to idle.
The crew probably did get the autobrakes off because if you let the airplane stop on auto-brakes, the last 80 knots or so feels very violent.
I'm sure the engineer types on here can give you a better explanation, but after a max braking effort situation (RTO or landing heavy for example) you cannot check the brake temps right away as your peak brake temps will occur a few minutes after the event is complete. Sounds like the A380 captain stopped the jet, waited the requisite time, saw that the temps were below limits and taxied the airplane to the gate. I have never got a good explanation if the temps are actually increasing (seems counter-intuitive to my simple pilot brain) or the energy is redistributing to where it is only later being picked up by the gauges as the energy is moving through the gear/brakes.
I assume that it's VH-OQD as FlightAware shows that it's been at LAX since 06.55 on Dec 9th. However VH-OQL operated QF12 which departed at 01.32 on Dec 10th, so I don't know why VH-OQD has been at LAX for two days. I doubt whether it would have flown out after it had a rejected take off three hours earlier, but who knows? FlightAware shows VH-OQL's last two flights as QF12 from LAX-SYD anyway, so does anyone know whether these are the two aircraft involved?