washingtonian
Topic Author
Posts: 749
Joined: Sat Sep 04, 2010 5:56 pm

How Close Was The Qantas A-380 To Crashing?

Tue Oct 04, 2011 7:57 pm

I don't mean to start a sensationalist thread, but how close was the Qantas A-380 with the engine explosion out of SIN close to crashing?
 
blackwidow
Posts: 47
Joined: Fri Feb 15, 2008 5:56 pm

RE: How Close Was The Qantas A-380 To Crashing?

Tue Oct 04, 2011 8:13 pm

Which leads me to ask - when's she gonna fly again?? Must be soon....
 
User avatar
SEPilot
Posts: 5022
Joined: Sat Dec 30, 2006 10:21 pm

RE: How Close Was The Qantas A-380 To Crashing?

Tue Oct 04, 2011 8:18 pm

I will put it in perspective. I just had a chance to see the Collings Foundation B-17 & B-24, and I recall pictures of B-17's that had limped back to England with incredible damage, including a couple that landed with only one operating engine, IIRC. Compared to those, the A380 was in good shape. But this was a very different situation, and from what I have read the crew had their hands full and did a magnificent job of getting the plane down safely. The only way to really tell how well they did is to put the same situation in the simulator and see how different crews cope with it (which I'm sure Airbus has done.) I have not heard any results of such an experiment, however. Just for another perspective, they did that after UA232, and none of the crews were able to get the plane anywhere near the airport, let alone make anything close to a controlled landing.
The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
 
planespotting
Posts: 3026
Joined: Sat Apr 17, 2004 4:54 am

RE: How Close Was The Qantas A-380 To Crashing?

Tue Oct 04, 2011 8:37 pm

Here is Patrick Smith's bullet point list (from his Nov. 18 "Ask the Pilot" article in Salon which cannot be linked to from this site for reasons that cannot be elaborated upon) of crap the flight crew had to deal with all at once:

- Complete, uncontained failure of No. 2 engine.
- Shrapnel hole on one of the left wing-flap fairings
- Large shrapnel puncture clear through the forward section of the left wing.
- Failure of the automatic bus transfer between the failed No. 2 engine and the still operating No. 1 engine, among other electrical problems
- Total loss of all fluid in one of the plane, two main hydraulic systems
-Substantial leaks in two of the plane, left wing fuel tanks
- lectronic and/or mechanical failure of important fuel transfer functions (leading to a fuel imbalance).
- Malfunction of the fuel jettison system.
- Partial failure of leading edge slats.
- Partial failure of speed brakes and ground spoilers (once on the ground)
- Loss of brake anti-skid system
- Inability to shut down the adjacent, No. 1 engine using normal or emergency ("fire switch") methods (meaning if the No. 1 engine had also failed or started on fire, there would have been no way to shut it down)

As you can see, it's quite the laundry list of failures and problems that probably had never been demonstrated in the simulator before (at least in aggregate).

[Edited 2011-10-04 13:52:00]
Do you like movies about gladiators?
 
SPREE34
Posts: 1574
Joined: Tue Jun 29, 2004 6:09 am

RE: How Close Was The Qantas A-380 To Crashing?

Tue Oct 04, 2011 10:02 pm

Quoting washingtonian (Thread starter):
close to crashing?

Not at all. Rudundancy worked.
I don't understand everything I don't know about this.
 
User avatar
gdg9
Posts: 770
Joined: Thu Jun 30, 2005 9:42 am

RE: How Close Was The Qantas A-380 To Crashing?

Tue Oct 04, 2011 10:11 pm

Great job by the professionals at QF in landing the aircraft.
@dfwtower
 
roseflyer
Posts: 9606
Joined: Fri Feb 13, 2004 9:34 am

RE: How Close Was The Qantas A-380 To Crashing?

Tue Oct 04, 2011 10:21 pm

Quoting SPREE34 (Reply 4):
Quoting washingtonian (Thread starter):
close to crashing?

Not at all. Rudundancy worked.

It was extremely close to not being able to land safely because the airplane had so many concurrent failures that affected the ability to land. So many parts of the airplane were damaged that the landing distance could not even be effectively calculated. No pilots train for that many failures at once. Redundancy worked, but it was on the ragged edge of being able to safely land the plane. Redundancy is based on statistics and no one would have predicted that a fan blade loss would result in that many failures.

With the leading edge damaged, a higher approach speed was necessary.
With the spoilers damaged, the airplane would not get sufficient weight on wheels to allow full effectiveness of the brakes.
With the loss of a hydraulic system, anti-skid was disabled.
With a fuel imbalance due to loss of fuel pumps and associated leak, the CG was off.
With loss of engine 1 controls, the engine could not be operated as usual or even shut down.
With fuel leaking on overheated brakes/tires, fire was possible.
With inabiliity to jettison fuel, airplane was overweight
With loss of electrical system, communications were partially limited.
If you have never designed an airplane part before, let the real designers do the work!
 
prebennorholm
Posts: 6447
Joined: Tue Mar 21, 2000 6:25 am

RE: How Close Was The Qantas A-380 To Crashing?

Tue Oct 04, 2011 11:41 pm

With the long list of malfunctioning subsystems they had better find a good long runway, preferably dry, and no adverse weather. That's also what they did.

The combination of fuel leak in one wing and non-functioning fuel dump was, however, a potentially dangerous thing. Had the leak been a lot more massive, then it could have produced a dangerous lateral imbalance.

Apart from that, redundancy worked. And thank God the flight crew staid cool and did what they were trained to do.

But I am pretty sure that the non-functioning fuel dump has provided a few sleepless nights in Toulouse. I could imagine that Airbus has investigated very carefully what exactly caused the fuel dump malfunction, and that they are (or have been) looking into ways to eliminate that, or build in an additional layer of redundancy there.

Quoting RoseFlyer (Reply 6):
...no one would have predicted that a fan blade loss would result in that many failures.

There was nothing wrong with the fan, it was the IP turbine disk which disintegrated.

Quoting RoseFlyer (Reply 6):
Redundancy is based on statistics...

What???? Redundancy is based on failure tolerant design.
Always keep your number of landings equal to your number of take-offs
 
roseflyer
Posts: 9606
Joined: Fri Feb 13, 2004 9:34 am

RE: How Close Was The Qantas A-380 To Crashing?

Tue Oct 04, 2011 11:57 pm

Quoting prebennorholm (Reply 7):
Quoting RoseFlyer (Reply 6):
Redundancy is based on statistics...

What???? Redundancy is based on failure tolerant design.

I'll expand a bit. Redundancy is based on tolerating a failure, but what type of redundancy is about the probability of a specific failure and the effects that it has. For example, the probability of landing gear deploying in flight causing excess drag on an overwater flight and leading to fuel starvation is so low that a redundant method for gear retraction is not required. However the probability of landing gear not being able to be deployed and causing a gear up landing is high enough that a secondary landing gear extension system is required on almost all airplanes.

What I am getting at is that the probability of a single engine failure mode taking out enough systems to result in a condition preventing a safe landing has to be low enough to be considered so improbable that it will not happen. My point is that the single event came very close to preventing the airplane from safely landing. The condition was so unlikely that not all parameters on the airplane could be used to calculate a safe landing distance since it was never thought that such an event could happen. In the end the airplane was able to make a safe landing, but I would not say that the airplane was not at all close to having an unsafe landing (going off runway, fire, etc). It took some exceptional skill by the crew to execute a safe landing.
If you have never designed an airplane part before, let the real designers do the work!
 
thegeek
Posts: 1330
Joined: Mon Nov 26, 2007 7:20 am

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 12:13 am

Quoting RoseFlyer (Reply 8):
My point is that the single event came very close to preventing the airplane from safely landing.

That would be your opinion though. Other posters have disagreed, in this thread and others.

I don't know if anyone has an objective answer to this question. If they do, I for one would love to see it.

Quoting prebennorholm (Reply 7):
The combination of fuel leak in one wing and non-functioning fuel dump was, however, a potentially dangerous thing. Had the leak been a lot more massive, then it could have produced a dangerous lateral imbalance.

How severe might this issue have been? Could you have run out of aileron authority to compensate for the imbalance? I'd be very surprised.

I suppose if all the fuel leaked out of the port wing, the #1 engine would also have (presumably) stopped, which with the still heavy weight from the full starboard wing tanks would have impacted your climb ability pretty severely. I'd still be very surprised if this effect was enough to cause you to hit the water.
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 12:33 am

Quoting washingtonian (Thread starter):
how close was the Qantas A-380 with the engine explosion out of SIN close to crashing?

The biggest thread, as RoseFlyer stated, was a runway overrun. There was no immediate threat of a crash because they had positive control of the airplane in all three axis and positive speed control. They had a ton of issues to deal with, but essentially none of them were threats to continued safe flight or landing. It's often very easy to forget that the gulf between normal airliner capability and inability to actually fly is very very very wide.

Quoting planespotting (Reply 3):
- Complete, uncontained failure of No. 2 engine.
- Shrapnel hole on one of the left wing-flap fairings
- Large shrapnel puncture clear through the forward section of the left wing.
- Failure of the automatic bus transfer between the failed No. 2 engine and the still operating No. 1 engine, among other electrical problems
- Total loss of all fluid in one of the plane, two main hydraulic systems
-Substantial leaks in two of the plane, left wing fuel tanks
- lectronic and/or mechanical failure of important fuel transfer functions (leading to a fuel imbalance).
- Malfunction of the fuel jettison system.
- Loss of brake anti-skid system
- Inability to shut down the adjacent, No. 1 engine using normal or emergency ("fire switch") methods (meaning if the No. 1 engine had also failed or started on fire, there would have been no way to shut it down)

None of these are threats to continued safe flight and landing because they're all covered by existing redundancy. You've lost levels of protection (many levels in this case) but you haven't lost any flight critical function.

Quoting planespotting (Reply 3):
- Partial failure of leading edge slats.
- Partial failure of speed brakes and ground spoilers (once on the ground)

This combination was probably the closest to being a threat to continued safe flight, as the combination isn't tested as far as I know. Either failure individually is tested but that doesn't guarantee the combination is also safe.

Quoting RoseFlyer (Reply 6):
It was extremely close to not being able to land safely because the airplane had so many concurrent failures that affected the ability to land.

None of them affected the ability to reach touchdown safely...a bunch affected the ability to stop. Hence the risk was much more of a runway overrun.

Quoting prebennorholm (Reply 7):
The combination of fuel leak in one wing and non-functioning fuel dump was, however, a potentially dangerous thing. Had the leak been a lot more massive, then it could have produced a dangerous lateral imbalance.

Full fuel tank drain due to rotor burst is a design condition and should be part of the aileron sizing criteria. It should be impossible to get a dangerous lateral imbalance due to a punctured fuel tank. Now, if they punctured two tanks, it probably depends on which two.

I am NOT trying to minimize the severity of this event, just trying to answer the OP's question. They weren't in any danger of crashing given the failures they had...given how many levels of protection they lost, however, they might have been a single failure away from certain fatalities.

Tom.
 
User avatar
kanban
Posts: 3663
Joined: Sun Jan 06, 2008 1:00 am

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 12:33 am

Quoting blackwidow (Reply 1):
Which leads me to ask - when's she gonna fly again?? Must be soon....

I saw somewhere a Feb 2012 date..
 
thegeek
Posts: 1330
Joined: Mon Nov 26, 2007 7:20 am

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 1:01 am

I think the answer to "how close was this flight to crashing" (other than a runway overrun) was how close they came to losing the remaining hydraulic system. Is that a known? Although it has happened that an A300 has landed after even this extreme loss of control.
 
XT6Wagon
Posts: 2645
Joined: Tue Feb 13, 2007 4:06 pm

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 1:11 am

Quoting thegeek (Reply 12):
I think the answer to "how close was this flight to crashing" (other than a runway overrun) was how close they came to losing the remaining hydraulic system. Is that a known? Although it has happened that an A300 has landed after even this extreme loss of control.

Many other ways they could have lost the lotto on where the pieces of the rotor disk went. I think someone here said that the A380 has a limited "manual reversion" capiblity for all hydraulics lost, but clearly more damage to the ability to control the plane would have been... dangerous.

The one that IMO they were most lucky to avoid was taking a major chunk of the compressor in the other engine. 2 engine out on the same wing... not likely to allow a return to the airport even if it was still controlable.
 
NWAROOSTER
Posts: 1032
Joined: Mon Feb 14, 2005 2:29 pm

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 1:35 am

The main thing taught pilots, when an aircraft is trouble. "Fly the Airplane."
This is what the pilots did and they did it well.   
Procrastination Is The Theft Of Time.......
 
thegeek
Posts: 1330
Joined: Mon Nov 26, 2007 7:20 am

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 1:36 am

Quoting XT6Wagon (Reply 13):
I think someone here said that the A380 has a limited "manual reversion" capiblity for all hydraulics lost

I think there is something for some of the tail surfaces, maybe pitch trim? But they did lose the EHA systems so I am pretty sure that the ailerons, for example, were not controllable had they lost the other hyd system in addition to the other damage.

Quoting XT6Wagon (Reply 13):
The one that IMO they were most lucky to avoid was taking a major chunk of the compressor in the other engine. 2 engine out on the same wing... not likely to allow a return to the airport even if it was still controlable.

I can only imagine that this would only be a problem at either low level (not enough time to fuel dump) or without the fuel dump capability. Of course the fuel dump capability was damaged, but even so, I expect the glide angle on the remaining two engines would have been shallow enough to return to SIN and risk a runway overrun in the worst case.

Or am I missing what you are saying?
 
XT6Wagon
Posts: 2645
Joined: Tue Feb 13, 2007 4:06 pm

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 1:47 am

Quoting thegeek (Reply 15):
Or am I missing what you are saying?

severe control issues in addition to a lack of thrust for this weight. I hope Airbus took the history of 747's that lost both engines on a wing into account since the 747 atleast is shooting a big gooseegg in suviving that. Yet, I doubt the A380 would retain full control with the two engines out even if no other damage occured. Thats just too many systems suddenly lacking hydraulic power, bleed air, and electricity. Nor would I expect them to design for it since independant failures of both engines on one wing should be as likely as winning the lotto on the same day as you win the indy 500. Also RR was supposed to insure that the chance of uncontained failure was 0.
 
thegeek
Posts: 1330
Joined: Mon Nov 26, 2007 7:20 am

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 2:21 am

Quoting XT6Wagon (Reply 16):
I hope Airbus took the history of 747's that lost both engines on a wing into account since the 747 atleast is shooting a big gooseegg in suviving that

That El Al freighter also had damage to the wing and/or its high lift devices, which was the main reason it crashed AIUI. It was also at a much lower altitude than QF32, so less options and also more weight due to more full fuel tanks.

Looking it up, I have to wonder if the pilots in that case were aware that the leading edge flaps were deployed on one wing but not the other. You would think they would notice the high aileron input required though.

Quoting XT6Wagon (Reply 16):
Also RR was supposed to insure that the chance of uncontained failure was 0.

Surely negligible, not 0.
 
qf002
Posts: 3126
Joined: Tue Jul 05, 2011 11:14 am

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 2:32 am

So in summary, she was very close to crashing, but it was a few strokes of luck that allowed the crew to maintain control and land the aircraft safely. If any one of the factors that contributed to the safe landing of that aircraft hadn't fallen into place then it's likely that the aircraft would have crashed, and I personally think that's pretty close to a crash, regardless of what others try to say about the aircraft being controllable etc -- that was pure luck IMO.
 
Type-Rated
Posts: 3901
Joined: Sun Sep 19, 1999 5:18 am

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 2:32 am

Quoting NWAROOSTER (Reply 14):
The main thing taught pilots, when an aircraft is trouble. "Fly the Airplane."

Fly the airplane FIRST.

Stabilize the aircraft, then attend to any problems that have come up. If you lose control of the aircraft what use is the rest of it?
Fly North Central Airlines..The route of the Northliners!
 
prebennorholm
Posts: 6447
Joined: Tue Mar 21, 2000 6:25 am

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 2:42 am

Quoting thegeek (Reply 9):
Could you have run out of aileron authority to compensate for the imbalance? I'd be very surprised.

Aileron authority increases with the square of speed. Meaning that at landing speed it is pretty low.

In case of, say, 100,000 lbs more fuel in the right wing than in the left wing, then it would have dictated a very high landing speed to maintain just a little roll control authority, and I could imagine 22 bust tires, therefore little breaking, and a very, very unpleasant runway overrun.

Quoting tdscanuck (Reply 10):
Full fuel tank drain due to rotor burst is a design condition and should be part of the aileron sizing criteria. It should be impossible to get a dangerous lateral imbalance due to a punctured fuel tank. Now, if they punctured two tanks, it probably depends on which two.

I agree with you, tdscanuck, and I am also pretty sure that in this case the lateral imbalance was only, or little more than, a trim problem.

But magnitude of catastrophic fuel tanks rupture is something which is difficult to design for. In addition it may happen at a more inconvenient place, say five hours flight away from nearest useful airport. It is more likely that it happens during climb, as it did, when the engines work harder. But in theory it may happen at any time from gate A to B.

It is the job of the airliner designers to learn from experience when incidents like this one happen. When things have a totally happy end like this time, then they shall imagine the same failures also with the worst thinkable magnitudes of the individual failures. And imagine whether the consequences would be any different.

I am pretty sure that the non-functional fuel dump and fuel transfer system is the single issue which have caused the most grey hairs in Toulouse. All the other failures, which developed on QF14, were designed for. But for sure they didn't install fuel dump and transfer abilities only for being inop in case of an uncontained engine failure.

Of course I have no idea what caused the inop dump and transfer, but if it was something as simple as a ruptured electric cable, then sure it can be improved with another layer of redundancy without much rocket science redesign.

Long range planes, where almost half of the take off mass is fuel, have the potential to develope uncontrolable imbalance, making fuel dump ability more than a convenience to avoid overweight landing, and also a primany safety issue.
Always keep your number of landings equal to your number of take-offs
 
JAAlbert
Posts: 1567
Joined: Tue Jan 31, 2006 12:43 pm

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 2:53 am

Why couldn't the crew shut down the engine? How did they eventually shut it down? Throw a hammer into it?
 
qf002
Posts: 3126
Joined: Tue Jul 05, 2011 11:14 am

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 3:07 am

Quoting JAAlbert (Reply 21):
Why couldn't the crew shut down the engine? How did they eventually shut it down? Throw a hammer into it?

Access was cut off by the wing damage (IIRC) -- fire crews slaughtered it with water, then when that didn't work with foam... It took 30+ minutes to get it stopped I think...
 
User avatar
zeke
Posts: 10107
Joined: Thu Dec 14, 2006 1:42 pm

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 3:22 am

Quoting washingtonian (Thread starter):
I don't mean to start a sensationalist thread, but how close was the Qantas A-380 with the engine explosion out of SIN close to crashing?

It was a rare combination of faults to deal with at once, however the crew that was flying the aircraft worked as a team and applied a conservative approach to resolving the situation. The actual flight on 3 engines and the approach back into SIN by all accounts was very smooth.

Quoting blackwidow (Reply 1):
Which leads me to ask - when's she gonna fly again?? Must be soon....

Repairs are well under way, looks like the deliberations in terms of dealing with the insurance aspects and compensation may have taken longer than the actual repair.

Quoting RoseFlyer (Reply 6):
It was extremely close to not being able to land safely because the airplane had so many concurrent failures that affected the ability to land.

I disagree, the pilot still had full control over the aircraft. In fact the crew used the autopilot down to about 1000 ft on final approach.

Quoting RoseFlyer (Reply 6):
So many parts of the airplane were damaged that the landing distance could not even be effectively calculated.

Calculating the landing distance is a red herring, the onboard landing distance performance application (LDPA) was actually able to calculate a landing distance after the crew changed the runway conditions from wet to dry. The LDPA calculated they had a 100 m buffer, they actually stopped sooner than LDPA calculated.

From the ATSB report

"The FO and the SCC input the affected aircraft systems into the landing distance performance application (LDPA) to determine the landing distance required for an overweight landing to runway 20C at Changi Airport of about 440 t, which was 50 t above the aircrafts maximum landing weight.

Based on the initial inputs to the LDPA by the flight crew, the LDPA did not calculate a landing distance. After discussion, and in the knowledge that the runway at Changi was dry, the crew elected to remove the inputs applicable to a landing on a wet runway and re-ran the calculation. This second calculation indicated that a landing on runway 20C was feasible, with 100 m of runway remaining. The crew elected to proceed on the basis of that calculation and advised ATC to that effect."

Quoting RoseFlyer (Reply 6):
No pilots train for that many failures at once.

I disagree, do a command course, they would throw a lot more than that at you in the command LOFTs.

Quoting RoseFlyer (Reply 6):
With the spoilers damaged, the airplane would not get sufficient weight on wheels to allow full effectiveness of the brakes.

According to the ATSB report, only spoiler #4 was inoperative, the aircraft has 8 spoilers per wing.

Quoting RoseFlyer (Reply 6):

With the loss of a hydraulic system, anti-skid was disabled.

According to the ATSB report, anti-skid braking was available on the body landing gear.

Quoting RoseFlyer (Reply 6):
With a fuel imbalance due to loss of fuel pumps and associated leak, the CG was off.

Nothing in the ATSB report to indicate that was the case. Aft or outer fuel transfer does not start at such low altitudes, and the aircraft would have been within CG limits on takeoff (which is also the landing CG limits). By default the CG will be 39.5% MAC, the forward limit is around 37% and aft limit 43% at their landing weight. The normal fuel burn sequence is inner tanks to feed tanks, mid tanks to feed tanks, and then the trim tanks to feed tanks, and finally outer tanks to feed tanks. The normal fuel sequence at this fuel level would have them burning from the inner tanks still. The messages regarding to CG would be relating to the aircraft being unable to do the after and inner fuel transfers that it normally does.

Quoting RoseFlyer (Reply 6):
With loss of engine 1 controls, the engine could not be operated as usual or even shut down.

According to the ATSB report, engine 1 was producing the commanded thrust in flight. The "degraded mode" refers to going from EPR as being the primary engine instrument to N1 control. i.e. instead of EPR limiting the maximum thrust in a go around, it would be a maximum N1.

“Consequently, the PIC set the thrust levers for Nos 1 and 4 engines to provide symmetric thrust, and controlled the aircraft’s speed with the thrust from No 3 engine.”

Quoting prebennorholm (Reply 7):
With the long list of malfunctioning subsystems they had better find a good long runway, preferably dry, and no adverse weather. That's also what they did.

Exactly.

Quoting prebennorholm (Reply 7):

The combination of fuel leak in one wing and non-functioning fuel dump was, however, a potentially dangerous thing. Had the leak been a lot more massive, then it could have produced a dangerous lateral imbalance.

The books actually say you can have in emergency situations 100% imbalance and still fly. The imbalance limits in the books are based upon structural limits for normal operations, they are not control related.

Quoting tdscanuck (Reply 10):
There was no immediate threat of a crash because they had positive control of the airplane in all three axis and positive speed control. They had a ton of issues to deal with, but essentially none of them were threats to continued safe flight or landing.

Correct, from the ATSB report

"Prior to leaving the holding pattern, the crew discussed the controllability of the aircraft and conducted a number of manual handling checks at the holding speed. The crew decided that the aircraft remained controllable"

"As the crew started to reconfigure the aircraft for the approach by lowering flaps, they conducted further controllability checks at the approach speed and decided that the aircraft remained controllable."

Quoting thegeek (Reply 12):
I think the answer to "how close was this flight to crashing" (other than a runway overrun) was how close they came to losing the remaining hydraulic system. Is that a known?

The A380 is the first large aircraft made that can continue to fly even with the loss of all hydraulic systems, this is due to having Electro-Hydrostatic Actuators (EHAs) and Electrical Backup Hydraulic Actuators (EBHAs) which continue to work even in event of a failure of the aircraft hydraulic systems.

The actuators are found symmetrically on on the inner and middle ailerons, spoilers 5&6, inboard and outboard elevators, as well as on the lower and upper rudder.

Quoting XT6Wagon (Reply 13):
I think someone here said that the A380 has a limited "manual reversion" capiblity for all hydraulics lost, but clearly more damage to the ability to control the plane would have been... dangerous.

With ailerons, elevator, rudder, and spoilers, I doubt anyone could say 'limited". It does not have the backup actuators on all roll control surfaces (it does on pitch an yaw), so only the roll rate would not be as fast as normal, however it is more than adequate.
We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 3:47 am

Quoting XT6Wagon (Reply 16):
Also RR was supposed to insure that the chance of uncontained failure was 0.

Not zero, just statistically very unlikely. I'm not sure how the exact fault tree runs for a rotor burst but if the chance was actually zero then you wouldn't have to design so much of the rest of the aircraft around it happening.

Quoting qf002 (Reply 18):
So in summary, she was very close to crashing, but it was a few strokes of luck that allowed the crew to maintain control and land the aircraft safely.

Fantastic design work by the Airbus engineers coupled with fantastic CRM by the flight crew is many things but it's not luck.

Quoting qf002 (Reply 18):
If any one of the factors that contributed to the safe landing of that aircraft hadn't fallen into place then it's likely that the aircraft would have crashed

I disagree; although they had lost many levels of protection they still had some left, especially on the things that really mattered. They had landing gear and brakes, they had flight controls, they had thrust. Airbus did a magnificent job.

Quoting prebennorholm (Reply 20):
But magnitude of catastrophic fuel tanks rupture is something which is difficult to design for. In addition it may happen at a more inconvenient place, say five hours flight away from nearest useful airport. It is more likely that it happens during climb, as it did, when the engines work harder. But in theory it may happen at any time from gate A to B.

That's why the requirement is to design for the worst possible case. Typically, that would be full tanks with total drainage of the most critical tank on the other side. Since, as prebennorholm noted, aileron control goes up with speed squared, the worst cases are at low speed (takeoff and landing).

Quoting prebennorholm (Reply 20):
Long range planes, where almost half of the take off mass is fuel, have the potential to develope uncontrolable imbalance

They shouldn't...the whole point of the design is that you can withstand the worst possible imbalance.

Quoting prebennorholm (Reply 20):
making fuel dump ability more than a convenience to avoid overweight landing, and also a primany safety issue.

Every airplane out there is fully capable of landing at MTOW. Fuel dump is a huge safety improvement but total loss of the fuel dump system should never result in loss of safe landing capability.

Tom.
 
thegeek
Posts: 1330
Joined: Mon Nov 26, 2007 7:20 am

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 4:19 am

Quoting zeke (Reply 23):
The A380 is the first large aircraft made that can continue to fly even with the loss of all hydraulic systems, this is due to having Electro-Hydrostatic Actuators (EHAs) and Electrical Backup Hydraulic Actuators (EBHAs) which continue to work even in event of a failure of the aircraft hydraulic systems.

My understanding is that these EHAs and EBHAs were non-functional for most surfaces in the case of QF32. Tried to dig up a link for that, and the best I've got before getting bored is: http://blogs.crikey.com.au/planetalk...ble-was-qf32-during-the-emergency/

It does say that only the left inner, right mid and right inner ailerons were functioning. If you have a chart of which systems power which control surfaces, you can infer which ones were knocked out by that. Sorry. If you are keen, I can try harder to dig up a better link later.
 
qf002
Posts: 3126
Joined: Tue Jul 05, 2011 11:14 am

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 4:34 am

Quoting tdscanuck (Reply 24):
Quoting qf002 (Reply 18):
So in summary, she was very close to crashing, but it was a few strokes of luck that allowed the crew to maintain control and land the aircraft safely.

Fantastic design work by the Airbus engineers coupled with fantastic CRM by the flight crew is many things but it's not luck.

Yet they were flying on a clear day, had a nice big and clear runway to return to and the engine shrapnel didn't puncture further systems or the fuselage, which was highly possible and would have lead to significantly poorer conditions for the pilots to control the aircraft. Sure praise where praise is due with Airbus and the crew, but the day could have turned out far worse if that 'explosion' had played out slightly differently or if it had been in the middle of a thunderstorm for example.

Quoting tdscanuck (Reply 24):
Quoting qf002 (Reply 18):
If any one of the factors that contributed to the safe landing of that aircraft hadn't fallen into place then it's likely that the aircraft would have crashed

I disagree; although they had lost many levels of protection they still had some left, especially on the things that really mattered. They had landing gear and brakes, they had flight controls, they had thrust. Airbus did a magnificent job.

So you're actually agreeing with me? If they hadn't had those levels of protection left (ie the design of the aircraft not working the way it was designed to) then they'd have crashed. If the aircraft hadn't maintained control of those things that matter -- gears, brakes, flight controls, thrust -- then it would have been a far worse situation...
 
User avatar
zeke
Posts: 10107
Joined: Thu Dec 14, 2006 1:42 pm

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 5:11 am

Quoting thegeek (Reply 25):
It does say that only the left inner, right mid and right inner ailerons were functioning. If you have a chart of which systems power which control surfaces, you can infer which ones were knocked out by that.

The ailerons are powered symmetrically.

• Outer ailerons are powered by green and yellow hydraulics, with conventional servocontrols
• Mid ailerons yellow hydraulics and the AC ESS BUS with Electro-Hydrostatic Actuators (EHAs)
• Inboard green hydraulics and AC 2 with Electrical Backup Hydraulic Actuators (EBHAs)

With yellow hydraulics available, I am not sure why the outer ailerons were not available, this maybe a function of the FBW being in roll alternate. AC 2 comes from the failed engine 2, in the event of a failed engine, any of the other remaining engine generators should automatically tie onto that bus. The ATSB report does not have that sort of details in it.

Green hydraulics come from the left hand engines, they also power the slats. The brakes have a similar level of redundancy with them as well, with a loss of complete hydraulics, they have a system called the Local Electro-Hydraulic Generation System (LEHGS) which provides local hydraulic pressure to the brakes.
We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
 
thegeek
Posts: 1330
Joined: Mon Nov 26, 2007 7:20 am

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 5:46 am

The way I remember the info is that the ESS bus was still working but not AC 1 nor AC 2, so even without the yellow hydraulics they should have had some roll control through the right mid aileron. Mightn't be enough to control a sizeable fuel imbalance though. They should also have had some sort of pitch control I guess from the ESS.

I guess that means I need to correct myself above: losing the yellow system they probably still could have gotten her down.

I'll see if I can dig up the info re: AC 1 & AC 2 later if you are interested.
 
beakerltn
Posts: 120
Joined: Thu Jul 09, 2009 8:18 pm

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 7:43 am

Quoting qf002 (Reply 22):
Quoting JAAlbert (Reply 21):
Why couldn't the crew shut down the engine? How did they eventually shut it down? Throw a hammer into it?

Access was cut off by the wing damage (IIRC) -- fire crews slaughtered it with water, then when that didn't work with foam... It took 30+ minutes to get it stopped I think...

This is the bit that continues to confuse me.

My understanding is that dual redundancy requires the redundant lines to not be co-located, thereby removing the risk of a single point of damage (in this case the wing damage) to remove all functionality. It would appear that engine control lines to engine #1 - which would unduobtedly be dual redundant - ran very close to each other.

If memory serves me correctly this has been a requirement since the Sioux city crash.
300/319/320/321/330/732/733/734/73G/738/744/772/77W/146/EMB135/EMB145
 
UALWN
Posts: 2177
Joined: Mon Jun 01, 2009 3:27 pm

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 8:29 am

Quoting qf002 (Reply 26):
If they hadn't had those levels of protection left (ie the design of the aircraft not working the way it was designed to) then they'd have crashed. If the aircraft hadn't maintained control of those things that matter -- gears, brakes, flight controls, thrust -- then it would have been a far worse situation...

Yes, and, as we say around here, if my aunt had a penis, we would call her "uncle"...
AT7/111/146/Avro/CRJ/CR9/EMB/ERJ/E75/F50/100/L15/DC9/D10/M8X/717/727/737/747/757/767/777/787/AB6/310/32X/330/340/380
 
Archer
Posts: 83
Joined: Wed Mar 23, 2005 7:07 am

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 11:04 am

What is the tail number/letters?
 
Nicoeddf
Posts: 513
Joined: Thu Jan 10, 2008 7:13 am

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 11:16 am

Quoting UALWN (Reply 30):
Quoting qf002 (Reply 26):
If they hadn't had those levels of protection left (ie the design of the aircraft not working the way it was designed to) then they'd have crashed. If the aircraft hadn't maintained control of those things that matter -- gears, brakes, flight controls, thrust -- then it would have been a far worse situation...

Yes, and, as we say around here, if my aunt had a penis, we would call her "uncle"...

Thank you very much - indeed my thinking!!!
 
777STL
Posts: 2770
Joined: Mon Dec 13, 2004 8:22 am

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 12:01 pm

Quoting Archer (Reply 31):
What is the tail number/letters?

VH-OQA - QF's first 380 delivered. (And the only one I've flown on!)
PHX based
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 1:53 pm

Quoting qf002 (Reply 26):
Yet they were flying on a clear day, had a nice big and clear runway to return to and the engine shrapnel didn't puncture further systems or the fuselage, which was highly possible and would have lead to significantly poorer conditions for the pilots to control the aircraft.

Nothing was wrong with their navigation or flight control capability...how would weather have changed the outcome?
Having a suitable diversion runway is always a requirement for any flying and it's true whether or not you've got damage, so the presence of a good diversion isn't luck.
Engine shrapnel puncturing the fuselage is bad for passengers but has no impact on the ability of the flight crew to fly or land the aircraft.
Now, if shrapnel had hit more systems, yes, they could have been in more trouble. But this was already a less than 1 in 1 billion event in terms of number of simultaneous systems taken out...they were already incredibly *unlucky*. It's certainly true that there's some combination of systems that could result in a worse situation, but that's a truism, didn't happen here, and would be even more incredibly unlikely than the initial incredibly unlikely event.

Given what the event actually was (and not what it could have been), they were not close to crashing. That was the OP's question.

Quoting qf002 (Reply 26):
the day could have turned out far worse if that 'explosion' had played out slightly differently or if it had been in the middle of a thunderstorm for example.

And if I had a Porsche 911 Turbo I'd be looking forward more to my morning commute.

Quoting qf002 (Reply 26):
So you're actually agreeing with me? If they hadn't had those levels of protection left (ie the design of the aircraft not working the way it was designed to) then they'd have crashed.

I absolutely agree with you that if they didn't have the levels of redundancy they did, they could have crashed.

I don't agree with you that it was lucky. They were actually incredibly unlucky; the chances of a single rotor burst doing that much damage has so many zeros on it pretty much everyone believed it to be "impossible" in the statistical sense.

Quoting qf002 (Reply 26):
If the aircraft hadn't maintained control of those things that matter -- gears, brakes, flight controls, thrust -- then it would have been a far worse situation...

If the airplane had crashed then it would have crashed. Of course a different event could have had a different outcome. But we're talking about this event, and they *did* have control of gear, brakes, flight controls, and thrust. Hence they were not in danger of crashing.

Quoting BeakerLTN (Reply 29):
My understanding is that dual redundancy requires the redundant lines to not be co-located, thereby removing the risk of a single point of damage (in this case the wing damage) to remove all functionality. It would appear that engine control lines to engine #1 - which would unduobtedly be dual redundant - ran very close to each other.

They were run very far apart...they just had terrible luck that both paths got severed.

Tom.
 
frmrCapCadet
Posts: 1123
Joined: Thu May 29, 2008 8:24 pm

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 3:42 pm

Somewhat analogous, by the end of WWII damage control and design was such that all of the five or so USS heavy carriers that sunk early in the war could have been saved given the lessons learned. There is a 'lot of ruin' in a big ship (naval or air), which has been designed to survive. This is a testimony to those unsung heroes, those who investigate ship losses and analyse how it might have been saved.
Buffet: the airline business...has eaten up capital...like..no other (business)
 
flipdewaf
Posts: 1595
Joined: Thu Jul 20, 2006 6:28 am

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 4:02 pm

Quoting qf002 (Reply 26):
If they hadn't had those levels of protection left (ie the design of the aircraft not working the way it was designed to) then they'd have crashed.

So you are saying that if something didn't work the way it was supposed to then something would have gone wrong?

Quoting qf002 (Reply 18):
So in summary, she was very close to crashing, but it was a few strokes of luck that allowed the crew to maintain control and land the aircraft safely.

F/O: OH NO!!! That uncontained engine failure means we are all going to die!!!

Captain:No no, by chance those silly people at airbus have accidently left some extra engines attached to the wings and some excess hydraulics in the plane, wasn't thats a stroke of luck.

Fred
Image
 
qf002
Posts: 3126
Joined: Tue Jul 05, 2011 11:14 am

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 4:12 pm

Quoting tdscanuck (Reply 34):

Your points are all true and valid. I think it ultimately depends on how you define close to crashing -- I'd say that if someone were to survive a car accident thanks solely to having an airbag that they were 'close to dying' but the safety system prevented that from happening. It's just my opinion that the same sort of thing applies to this incident. The aircraft was in a dangerous place, it was just the systems that prevented a crash. Not saying anyone has to agree with me -- that's just my personal opinion on the topic...
 
baroque
Posts: 12302
Joined: Thu Apr 27, 2006 2:15 pm

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 4:52 pm

Quoting flipdewaf (Reply 36):
F/O: OH NO!!! That uncontained engine failure means we are all going to die!!!

Captain:No no, by chance those silly people at airbus have accidentally left some extra engines attached to the wings and some excess hydraulics in the plane, wasn't that a stroke of luck.

So I need to check on the number of engines each time I get on an A380, good point there, otherwise my luck will run out. Should I ask the pilot if he has the requisite number of hydraulics systems too, I think that would be best, or I might become an Auntie - a terrible fate to suffer after I ridden to the airport in Tom's Porsche 911 Turbo.
 
n729pa
Posts: 682
Joined: Thu Jan 20, 2011 6:16 pm

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 5:07 pm

Rather than a load guess work and theory, why not have a read of the ATSB accident report.

http://www.atsb.gov.au/publications/...reports/2010/aair/ao-2010-089.aspx

Personally I found there was a lot more detail in this report than was made known at the time, and the seriousness of the incident is plain for all who read it.

Luck played a part, it often does. It had only just taken off from Singapore, it wasn't over the Pacific Ocean, or thousands of miles away from a suitable airport to land at. The nearest place, was where it had just departed from.

The crew had a difficult landing too, and like the BA volcanic ash 747 and the US Airways Hudson River A320 and other incidences. It can't understated or underestimated what a great job and display of airmanship the crew performed to get her down, it was a tribute to the Qantas crew that she was able to land and land safely.

If the damage was that insignificant .....why has it taken so long to assess and repair? That does also highlight the extent of the damage that occured.

It's often only takes the sightest thing to turn an incident into a full blown accident, and reading the report they had plenty of issues to deal with on board, and we are now very fortunate to be discussing this as it is, and not how it could have been.
 
User avatar
Francoflier
Posts: 3790
Joined: Wed Oct 31, 2001 12:27 pm

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 5:15 pm

Does anybody know whether Airbus has implemented software and/or hardware mods to address the systmes faults which led to the fuel imbalance, inability to dump fuel and to shut down #1?
I'll do my own airline. With Blackjack. And hookers. In fact, forget the airline.
 
User avatar
Faro
Posts: 1505
Joined: Sun Aug 12, 2007 1:08 am

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 7:09 pm

So long as flight control was maintained, the A380 was IMHO as far from crashing as this Tu-154 was far from landing safely:

http://www.youtube.com/watch?v=BpOmzjUHVy8&feature=fvwrel

Truly amazing that the Tu-154 suffered no fatalities...control is everything.

Faro

[Edited 2011-10-05 12:47:32]
The chalice not my son
 
VgnAtl747
Posts: 1333
Joined: Fri Apr 06, 2001 3:59 am

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 7:21 pm

There is an investigative report from a show called Four Corners that was pretty good. It has interviews with the crews and everything: http://www.youtube.com/watch?v=MHb9gjOFEbA
Work Hard. Fly Right. Continental Airlines
 
User avatar
yellowtail
Posts: 3750
Joined: Fri Jun 17, 2005 3:46 am

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 8:16 pm

Quoting zeke (Reply 23):
It was a rare combination of faults to deal with at once, however the crew that was flying the aircraft worked as a team and applied a conservative approach to resolving the situation. The actual flight on 3 engines and the approach back into SIN by all accounts was very smooth.

IIRC....there were also one or two extra senior captains on the flight doing training or something of the sort....and they helped with the CRM.
When in doubt, hold on to your altitude. No-one has ever collided with the sky.
 
Slcpilot
Posts: 578
Joined: Thu Aug 07, 2003 3:32 am

RE: How Close Was The Qantas A-380 To Crashing?

Wed Oct 05, 2011 10:03 pm

The A-380 was clearly able to physically fly, and presumably without heroic control inputs from its crew. There is little doubt in my mind ANY airbus crew could have landed the plane given the damage that occured.

For me, the answer of how close the plane came to crashing lies very closely with the issue of how close the fuel leak came to igniting. We can look at some historical events that had similar charactoristics.

-Concorde (IAD) - tire parts through the wing, no fire
-Concorde (CDG) - tire parts through the wing, fire
- A-300 (Iraq) - missle, fire, very, very lucky!

It is my own personal suspicion that the Qantas A-380 was VERY lucky the vaporizing fuel leak did not find an ignition source when the hot turbine section penetrated the wing, and if it had, the results would have been fatal for all, despite any crew inputs. I suspect any fire would have had cascading ill effects on systems as well as structural integrity.

SLCPilot
I don't like to be fueled by anger, I don't like to be fooled by lust...
 
prebennorholm
Posts: 6447
Joined: Tue Mar 21, 2000 6:25 am

RE: How Close Was The Qantas A-380 To Crashing?

Thu Oct 06, 2011 2:35 am

Quoting SLCPilot (Reply 44):
-Concorde (IAD) - tire parts through the wing, no fire
-Concorde (CDG) - tire parts through the wing, fire
- A-300 (Iraq) - missle, fire, very, very lucky!

It is my own personal suspicion that the Qantas A-380 was VERY lucky the vaporizing fuel leak did not find an ignition source when the hot turbine section penetrated the wing...

The Concorde at CDG was different. The tank leak fed fuel into the #1 and #2 engine intakes and put them on fire. And the primary reason for the disaster was stall due to insufficient engine thrust.

Feeding the intake from a leak is not possible on a "normal" airliner with wing mounted engines.

I don't think that even hot shrapnel rupturing a fuel tank makes a high risk of fire. Not with jet fuel. With AVGAS it is a different story. An exploding missile warhead (A300 Iraq) is a different animal, but even with that trailing fire (and some luck) they were able to land.

I am not telling that I am sure the Concorde CDG pax would have lived to tell their story in case they had had three good engines to avoid the stall. But maybe? With two good engines only they were doomed "by design".
Always keep your number of landings equal to your number of take-offs
 
baroque
Posts: 12302
Joined: Thu Apr 27, 2006 2:15 pm

RE: How Close Was The Qantas A-380 To Crashing?

Thu Oct 06, 2011 2:52 am

Quoting prebennorholm (Reply 45):
I don't think that even hot shrapnel rupturing a fuel tank makes a high risk of fire. Not with jet fuel. With AVGAS it is a different story. An exploding missile warhead (A300 Iraq) is a different animal, but even with that trailing fire (and some luck) they were able to land.

Even with Avgas, a the climb speed of an A380, the speed of the flame front might not be enough to keep a fire going. Hence the tactic of bombers in WWII to dive to put out fires with AVGAS.

It was a serious incident, but they were not lucky, there were systems in place to cope with most unexpected situations.

And the FA who had been on that flight that I met about 10 days ago was not a bit fazed at being on the A380. Would he continue with his great smile if he thought it was luck? I rather doubt it.
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: How Close Was The Qantas A-380 To Crashing?

Thu Oct 06, 2011 3:19 am

Quoting qf002 (Reply 37):
I think it ultimately depends on how you define close to crashing -- I'd say that if someone were to survive a car accident thanks solely to having an airbag that they were 'close to dying' but the safety system prevented that from happening.

I agree that it depends on how we define "close to crashing" but I think the airbag analogy is flawed...they had more than one system still left protecting them. They had all major flight control functions working...that's a far cry from considerably more damaged airliners that have managed to survive.

Quoting qf002 (Reply 37):
The aircraft was in a dangerous place, it was just the systems that prevented a crash.

Aircraft are *always* in a dangerous place...you're accelerating a couple of hundred tons of metal to near supersonic speeds several miles above the earth. It's always the systems that prevent a crash (on a modern airliner, anyway). In this case, redundancy and good design ensured that, even with very significant damage, the crew had all the systems they needed to prevent a crash. If this aircraft had crashed in the condition it was actually in, it would have been a flight crew error...they had everything they needed to safely fly and land.

Tom.
 
XT6Wagon
Posts: 2645
Joined: Tue Feb 13, 2007 4:06 pm

RE: How Close Was The Qantas A-380 To Crashing?

Thu Oct 06, 2011 3:26 am

Quoting tdscanuck (Reply 34):
Nothing was wrong with their navigation or flight control capability...how would weather have changed the outcome?

Bad weather increases the risks to a huge degree. It adds to the crew workload/stress. It puts extra stress on the damaged components. It can require larger and more frequent uses of the control surfaces.

Would it have brought down the A380 in this case? well, I doubt it unless it was nearly typhoon level weather. The real danger IMO would be having a wet runway causing an overrun.
 
User avatar
zeke
Posts: 10107
Joined: Thu Dec 14, 2006 1:42 pm

RE: How Close Was The Qantas A-380 To Crashing?

Thu Oct 06, 2011 10:20 am

Quoting tdscanuck (Reply 47):
I agree that it depends on how we define "close to crashing" but I think the airbag analogy is flawed...they had more than one system still left protecting them. They had all major flight control functions working...that's a far cry from considerably more damaged airliners that have managed to survive.

As far as the flight control computers were concerned, it was not a big deal, they were still in normally pitch and yaw laws, and alternate roll. The autopilot was still available, and was used by the crew until they disconnected it off on final.

Quoting XT6Wagon (Reply 48):
I doubt it unless it was nearly typhoon level weather.

Not something that is associated with geographic locations so close to the equator.

Quoting XT6Wagon (Reply 48):
The real danger IMO would be having a wet runway causing an overrun.

A wet runway in itself should not significantly change the landing distance, especially at an airport like Singapore where they have adequate grooves and camber providing a surface which is not flooded. Dynamic hydroplaning is normally associated with large areas of standing water, this is countered with runway camber. Viscous hydroplaning is normally associated with thin films of water on smooth runways, this is countered with grooves and making a positive touchdown. Reverted rubber skidding is a combination, and it is countered by a combination of grooves and camber.

Please note in aviation there are specific definitions that differentiate between dry, wet, and contaminated runways.
We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos