Unlikely to block the runway. They had one good engine; good enough to return to Perth.
And no shortage of taxiways. See following.

Learmonth RAAF Base in WA - ABC News (Australian Broadcasting Corporation)

Anyway, it has all been said already.
As Piltdown Man suggested, let's see what comes out in the wash.

There is a big diffference between a engine failure and the level of vibration that airframe was experiencing. There was a very real possibility that engine could separate from the pylon with possible catastrophic results.

Needless to say, he couldn't resist:

AirAsia has long record of safety failures - Geoffrey Thomas, Aviation Editor

"The terrifying engine failure involving an AirAsia X A330 yesterday is the latest in a string of serious incidents and accidents to trouble the AirAsia Group"

etc, etc (you get the idea).

And decided nevertheless to land at the nearest "suitable", even though it had two engines running perfectly and YPLM has limited medical facilities, is isolated, has limited RFF, limited ATC, &c, &c.

So what then made it "suitable" in that case?

I have been to the airport there a few times, I guess I was just playing a bit of "what if" as well.

Living in the NW I have a fair idea of the resources available and I just suspect it wouldn't be as straightforward as some people seem to think if it did all go pear shaped I guess was more my point. Sure if you have no options I'd be headed there but I can only presume at the time with the information they had they decided PH or somewhere further south was a better option was all.

An extra 359 in a town of about 2500 is a fair impost even with an airline potentially throwing money around.

The video shows us a vibration that corresponds to about 480 rpm (8 cycles per second).
That sounds more like windmilling than anything else.

Fair enough. So have I.
I'm not unaware of the inconvenience (at the very least) of diverting to Exmouth.
I guess my interest revolves around the seemingly diametrically opposed opinions being posted in this thread versus the Swissair case in Iqualuvit a couple of months ago.

It seems to me that there is wildly varying interpretation of what constitutes "suitable".
And I don't understand why that should be the case.

It seems that in the case of QF72 the crew gave priority to the condition of the aircraft and their uncertainty about that condition, above all the other factors mentioned by other contriburors.
In this AirAsia case that does not seem to have been the case.

It appears in the Boeing 777 FCTM, Chapter 8, Non-Normal Operations, Landing at the Nearest Suitable Airport; I suspect that most Boeing FCTMs contain a similar passage.

In some FCTMs there is a cross-reference to Supplemental Information along the lines of;

My bolding.

Learmonth does not meet ICAO Rescue and Fire Fighting Services Category 9 standards (as required for airplanes 61 m ≤ length < 76 m) and therefore fails the "adequate facilities" test as a suitable airport for an A330-300.

I would disagree. When I worked out there, some would pray before every crosswind landing; yet I have never seen an Atheist pray before a difficult landing or situation. Much to their disappointment, I made them agree that the landing would be made by skill, not by divine intervention.


For the vibration to continue, it is highly likely that it was an N1 blade failure. Shame you cannot feather them, eh? Will be interesting to see why the blade failed. An earlier bird strike, perhaps??


For the vibration to continue, it is highly likely that it was an N1 blade failure. Shame you cannot feather them, eh? Will be interesting to see why the blade failed. An earlier bird strike, perhaps??

Not discounting the previously mentioned inputs to the PIC's decision process, but its highly likely they have an operator customised EFB running Jepps with only the company approved airport charts on board. Learmonth probably not even charted as far as Air Asia concerned. Plenty of foreign airlines running across Australia without charts for suitable en route aerodromes. With Casa issued foreign AOC's. Who's to blame for this?

What originated "on a wing and a prayer?"

All home safely
 

We tend to overinterprate casual emergencies. Words from the Captain. Chosen airfields. All souls got back safely. End of story.

Here we go...
The minimum RFF category for ETOPS/EDTO is 4.
Learmonth has been assessed as adequate to nominate as an ERA alternate by many airlines.
Most Asian aircrew rely heavily on decisions made by their operations centres in the event of non normal situations. It is common for Asian OCs to place operational convenience ahead of regulatory requirements. I don't think they deliberately ignore the rules, it's more likely a combination of legacy mindset from four and three engine days, and confusing EDTO literature that doesn't translate well from English (there are plenty of confused posters in this thread too...).
It's not a stretch to suggest that they only had Notams and information for the alternates specified on their flight plan and were unaware of the availability of Learmonth.

Other than Perth itself, Learmonth would have to be one of, if not THE, best alternate for heavies coming from or heading west.

I seriously doubt that any of the other WA regionals have better facilities / capability overall.

St Christopher was the patron saint of travellers when all forms of travel were dangerous.


That people do not pray nowadays says something about how safe the world is perceived to have become.

Yes, maybe.
Better facilities and access to support.

But I'd put runway specs at the top of the list and an extra 800 metres might come in handy with a single engine landing.
Support facilities come second provided you're not on fire.

And YPPD is quite a bit farther north.

Yeah I missed the west bit in your post so deleted it, not quick enough apparently :)

Tell passengers to pray during an emergency........

Unprofessional, inappropriate, and reckless!!!!!

Termination of the pilot by management the only acceptable response.

For those of you thinking the aeroplane was about to shake itself apart, Mr Boeing offers this advice:
I wonder if Airbus has the same faith in its own airframes/systems.

Folks,
I'm with Sailvi767 on the inspection of pylons and other critical structure, given the severity and length of time of the vibration.
I know nothing about Airbus pylons at all, but I do know quite a bit about Boeing/Douglas pylons, including a number of in-service failures.
Tootle pip!!

Interesting.

But it all still seems very subjective to me. I would hope that there is further advice that better defines the circumstances that they are describing.
Was the vibration level observed in the passenger's video "high", as envisaged by the advice from Boeing?
Or was it "extreme"and way beyond anything they ever considered? ((Not saying it was. Just asking)

And how long did they anticipate that the vibration would last or be tolerated for?

Be interesting to know if there was any suggestions from their IOC ?
Yes I know it should not come into a decision and yes I know the captain has final authority .

Only a guess, but given that the A330 is certified for EDTO operations, I'm guessing that they would have considered prolonged vibration after a failure like this, up to and beyond the EDTO distance/time that the aircraft is certified for?

morno

Given that the situation Boeing describes seems to be the exact situation the XAX experienced (fan blade separation) I'd suggest that this is the "severe" vibration they mention.

Mind you, there may be a difference in the levels of vibration experienced by a Boeing compared to an Airbus in the same scenario but I can't imagine an Airbus would be much more likely to self destruct.

The vibration level observed in the passenger cabin was similar to other events and of little relationship to highly damped structural systems in the airframe.

As stated much earlier it is way below the expectations for continued flight in turbulence and gusting levels.

Of course some local parts (tubing, brackets, etc.) associated with the failed engine pylon need be inspected before flight.

I expect that the Australian ATSB will later report on findings.

I'm still awaiting any glimpse of overall photos of the fan as I can't see any great fan damage including the cowl

If you think the vibration was bad enough to require an inspection AFTER the fact why would you continue to fly 300 nm farther PRAYING that the engine pylon won't fail?

No maintenance? Who cares, the plane is grounded for days?
No customs? Does not matter in an emergency. And they were returning to the country of departure so there's no need for customs if you insist in being ridiculously pedantic.
Limited medical? No one is injured.
Limited ARFF? They're not burning, they're trying to land before possible structural damage.

https://thewest.com.au/news/wa/airas...-ng-b88518000z

ref above: in the article it states "a source said the pilots were alerted to the problem by a monitoring system and then heard and felt the vibration from the stricken engine, they shut the engine down, did a 180-degree turn and returned to Perth".

My opinion is such: Vibration meters alerted the crew, get a high vibe level - perform a precautionary shut-down, return to Perth. Engine gets changed and the people don't get freeked out along with what now is obviously a difficult procedure to determine "what inspections are necessary"?
In a perfect world this is what "should have happened" but probably did not. The crew got alerted and before you knew it (check-list out and performing it) the Fan blade separated. Large fans require maintenance every so often for lubrication, inspection, balancing, overhaul.
I suspect this is a maintenance related issue.

As far as landing at the nearest suitable airport vs what probably was a coaxing of the operator for the FLIGHT CREW TO RETURN to Perth where the company handed out bottle water and $20. vouchers to a group of emotionally changed passengers in need of Post Traumatic Stress Syndrome DEBRIEFING WITH QUALIFIED EMOTIONAL SUPPORT PERSONNEL. (dramatic changes in life experience often occurs to individuals with PTSD in short time. Marriages, relationships, addiction, phobia's etc etc).

since WHEN did all souls getting back safely end anything?

since when should it?

is the author a pilot?

Fair enough.
I would suggest to you that Learmonth is approved by many large carriers as a full alternate, Suitable alternate or whatever title each airline uses, for a very long time. For example, it has been the No 1 Alternate for Perth for QF Boeing 747s since the 1970 s. If they can't use Learmonth (1.30 away) they have to use Adelaide(2.30+ away) with consquential penalties.
If each airline allows each individual pilot to determine what constitutes "suitable" then that is a very variable standard in my view.
I don't know, but my guess is that Learmonth is used by a number of A380 airlines as a full Alternate for Perth and ergo, if that particular airline considers it safe and appropriate for an A380 that just needs to fuel up, it would be considered safe and appropriate for an A330-300 with an engine shutdown and vibrating, lack of RFF notwithstanding.

It is down as a suitable alternate for the A380. You worry about the logistical problems once you have safely got your passengers and crew on the ground. If you remember QF72 (A330) when the computers went haywire the captain couldn't get the aircraft down to Learmonth fast enough and didn't give a damm about support or maintenance at the airport. He was concerned with saving lives. Learmonth had a runway he could use, and that was that.

The problem with so many of the assumptions in this thread is that the remaining engine WILL get the plane back to Perth. This is a huge assumption on a trip of several hundred kms after an engine failure of unknown cause, when the crew could have landed safely nearby.

That remaining engine is subject to extra stress and higher loads because it's operating for two, at a reduced height, higher drag and higher fuel burn. Life is more important than maintenance facilities and emotional support people at destination. If you lose one engine, the chances of losing the other are a lot higher in this scenario, and then it's the desert and bye bye.

Correction: It's not an official alternate for the A380 as I previously implied, but its a runway an A380 captain would have no hesitation in using if needs must.

What's with the warning from the Captain, " Our survival depends on your cooperation", what can pax do apart from sitting down and belting up, and it appears the capt put maint support ahead of the safety of the pax with his decision to return to Perth, a 90 min flight on one good engine , with the other vibrating madly, the stress on everything from the turbine shafts, pylons, wing structure and fuselage must have been considerable.

My exact thoughts too, remind me not to fly AirAsia anytime soon, it's a wonder the engine didn't depart the wing.

If they had landed at Learmonth, wouldn't it be fairly straightforward to send another plane up from Perth to pick up the pax and transport them back to Perth on a plane that wasn't trying to shake itself to bits.

Are they? Do you have a statistical source for this? The central assumption behind ETOPS is that cruise engine failures are independent of one another with one engine operating at Max Continuous Thrust for the maximum ETOPS time limit.

If there is a dependant relationship between the two engines (common fuel source or an engine failure damages another engine) then this assumption is no longer valid, and getting on the ground ASAP is a must. A blade failure at cruise altitude is likely to be a random event within the ETOPS time limit (ie the second engine suffering a random failure with say a 180 minute ETOPS segment is vanishingly small).

Even if there is a identical common point of failure of engine maintenance for both engines, the chances of the both failures occurring within the one flight is statistically incredibly small. In other words, the engineering is designed to get you home from the the worst case scenario. Sure, it would feel very very uncomfortable, but it will work.

We accept this engineering rational every time we go flying in a twin. Here is a primer from EASA on the IFSD rates and engineering assumptions: Extended Range Operation with Two-Engine Aeroplanes ETOPS Certification and Operation. Have a look at section 3: RISK MANAGEMENT AND RISK MODEL (page 35), see Figure 1 and look at the IFSD rates per 1000 flight hours, and how they derive Figure 2 and the IFSD rate as ETOPS segments goes out towards 10 hours (0.010 failures per 1000 flight hours). If the second engine still works after the first blows up, it will keep working until you land.

Recent incidents that shows that dual engine failures were dependant: US Airways Flight 1549, QF32 and Air Transat 236. In all cases, there was a dependant relationship between the failures (external, birds for Sully, engine disintegration causing a second engine problem for QF32 and the Air Transat crew mishandling a fuel leak causing a common point of failure for the Azores Glider)


Having said all that, in this scenario I would be proceeding to the nearest runway that I believed was safe given my knowledge of the local environment. For me, YPLM is OK, for another pilot who is less familiar with the area that may be YPPH.

This short video shows where a random independent process becomes dependent one. The final simulation appears to defy logic and reason and does not produce the expected normal distribution.

Matt48 - "a 90 min flight on one good engine , with the other vibrating madly, the stress on everything from the turbine shafts, pylons, wing structure and fuselage must have been considerable"


Exactly. Why subject the operating engine to additional stress? How many hours has the good engine been tested at the vibration level it was experiencing?

:) Good one, and perhaps a food truck and chairs.

Its covered in the EASA ETOPS document.

My opinion and thinking:

Something goes "bang" and an engine stops. You can't pull over and have an engineer have a look and even if you could, the airplane would be grounded for weeks and maybe months. How do you know what damage has occurred? How do you know the last bolt holding a wing on isn't going to let go?

In this situation, in addition to the bang and the engine stopping, the entire fuselage engine and wing was shaking. The airplane and its occupants belongs on the ground and YPLM is long enough, wide enough and hard enough to not cause further danger. It was day time the terrain around the airport is forgiving and its hardly Broome in the dry season traffic wise.

Forget the problem with the stairs, hotels and every other thing you can dream up.

https://www.youtube.com/watch?v=6XU0nAGKLYY

Whilst very different the Sioux city crash shows what fragments at high speed can do to an airplane.

How many stuff ups can one have before a spade is called a spade? Are Europe and the US wrong?

The Captain should be considering his passengers safety first and foremost, screw the lack of facilities, someone elses problem once he lands the plane. Safety first, one engine U/S, the other going flat out on a vibrating wing for 90 mins, what could go wrong.

It will be interesting to see what comes out of this. If you consider how much pressure CASA puts on local operators it begs the question what does a foreign operator have to do to get it's AOC revoked or investigated by CASA?

Air Asia have had two very close calls in Australia now they're flying past perfectly acceptable alternates on one engine.

My money is on CASA doing nothing as per usual as they are not interested in upsetting a foreign country, and will just continue hammering the local operators and making what is already an uneven playing field even more uneven.