Ask The Pilot

[jb747]

With this final scenario in mind, assuming you couldn't communicate with ATC either, how would you land? Just fly in?

I would fly whatever path (i.e. STAR) I considered to be the standard, to whatever runway I needed, using the full approach. Prior to the start of the STAR, I would fly the flight plan exactly. If there's a gap between the start of the STAR and the flight plan (quite common), I'd just go from the last waypoint directly to the STAR. If it was a place I know well (like London or LA) I would descend in accordance with their 'normal' profile, otherwise as required by the approach.

ATC are smart, they'd work it out. Even though you haven't been able to declare it, they'd treat you as an emergency aircraft.

 

[jb747]

Forgot about phones; mine is always turned fully off

That's nice. They don't work at altitude anyway....but, once down low (10,000 feet or so) you might be able to get a connection.

 

[Quickstatus]

Hi JB747,

how do the a380 engines start? APU air compressor. I dont remember the cabin air stopping for startups

 

[por930]

I would fly whatever path (i.e. STAR) I considered to be the standard, to whatever runway I needed, using the full approach.......

jb, when on approach to Dubai from Australia, for 30L or 30R do you mostly use the BUBIN 7C or 7D STAR (as I always seem to get as we do the double U turn approach) or have you ever got a straight in approach? If you are required to hold, is it usually in the BUBIN area or earlier?

 

[jb747]

Here's an idle thought. I wonder that in the not too distant future, people on the ground would be able to take full control of a FBW aircraft (ie locking the coughpit out of control completely) in certain very extreme circumstances - for instance non responsive coughpit with plane deviating from flight path, or coughpit invasion and loss of control of circumstances by pilots . I'm thinking the autopilot would be 'programmed' to land the plane at earliest opportunity or at least have it taken out of harm's way (either from the aircraft's or ground's point of view). I'm not suggesting that successful intervention would always be possible but I wonder if it may be possible technically if there was a datalink between the plane and the ground?

In theory anything is possible. But, it would seem to me that it opens a can of worms that is currently closed. The aircraft simply cannot be controlled from the ground at the moment, nor are many of the systems accessible from the computers (i.e. they can't manipulate the gear or flaps). As soon as you put the sort of system you envisage into existence, it would become the #1 hackers target, and sooner or later, someone will succeed.

It has exactly the same issues as the 'back door' that so many security services seem to want into your personal encryption. A back door will eventually be opened....

I would feel much less safe being on such an aircraft. In fact, I'd rather drive.

 

[Mattg]

I was wondering, hypothetically... would ATC ever tell a flight crew to "go around" if they could see that they were dangerously too high/ too low/ off course on their approach? Or short of calling for a go around, would they ever mention something to the pilots if they noticed something unusual but that didn't fall directly within their duty of separating aircraft? Or is this kind of thing left solely at the discretion of the flight crew?

 

[juddles]

In theory anything is possible. But, it would seem to me that it opens a can of worms that is currently closed. The aircraft simply cannot be controlled from the ground at the moment, nor are many of the systems accessible from the computers (i.e. they can't manipulate the gear or flaps). As soon as you put the sort of system you envisage into existence, it would become the #1 hackers target, and sooner or later, someone will succeed.

It has exactly the same issues as the 'back door' that so many security services seem to want into your personal encryption. A back door will eventually be opened....

I would feel much less safe being on such an aircraft. In fact, I'd rather drive.

I totally, totally agree with JB on this. These days, if terrorists, etc manage to circumvent security procedures, they may succeed in dropping a couple of airplanes, as per 9/11. If remote control was made possible, and "they" succeeded in cracking that, they could drop one thousand aircraft simultaneously.

And that, Ladies & Gentlemen, would be the end of air travel as we know it.

 

[jb747]

Hi JB747,

how do the a380 engines start? APU air compressor. I dont remember the cabin air stopping for startups

The air conditioning packs are left on for a normal APU start, though they are turned off for any starts using external air. The fans are always on, so there will still be flow from the vents.

 

[jb747]

jb, when on approach to Dubai from Australia, for 30L or 30R do you mostly use the BUBIN 7C or 7D STAR (as I always seem to get as we do the double U turn approach) or have you ever got a straight in approach? If you are required to hold, is it usually in the BUBIN area or earlier?

The runway modes at Dubai, will normally have landings on the left, and take offs on the right. Like everything, that's not absolute, but most traffic will operate that way.

From Australia, the normal arrival is the BUBIN 7C, though you'll very likely cut out the section after VELAR, and just be radar vectored on to finals. Holding happens at BUBIN. Straight in approaches happen sometimes, but mostly on delayed flights that happen to turn up outside of the busy periods. The BUBIN 8A is used for 12L, again with a fair chance of the base turn position being cut short.

Coming from the UK, DESDI 8A and 8C will be used, with holding at DESDI. Straight in for 12L is reasonably common.

 

[jb747]

I was wondering, hypothetically... would ATC ever tell a flight crew to "go around" if they could see that they were dangerously too high/ too low/ off course on their approach? Or short of calling for a go around, would they ever mention something to the pilots if they noticed something unusual but that didn't fall directly within their duty of separating aircraft? Or is this kind of thing left solely at the discretion of the flight crew?

ATC can most certainly tell an aircraft to go around, and they can also call for a stop for an aircraft on the take off roll. The most common cause of either would be another aircraft or vehicle infringing (or looking like it will) the runway. There's only a small window for it to work on take off, as there's a good chance it won't be heard, and it won't be obeyed past V1. Dubai issued a stop to a friend flying an Emirates 777 a while back, as a result of a go around on the other runway. I was once told to go around in London, after another aircraft failed to stop as instructed.

As for too high, etc. I've never heard anything like that, but I doubt that ATC would sit there and say nothing. Nevertheless, they aren't there to tell the pilots how to fly (though I'm sure they'd sometimes like to). The difference between a normal landing and one that is likely to be an accident is only about 60', so I don't know that they would even be in a position to see it.

 

[cambriamarsh]

Hi JB, Boris and everyone else that contributes to this thread, thanks for your ongoing dedication to our education.

IMG_2859.JPGNow that we seem to be moving more and more to big twins rather than four engined jets for long hauls, ETOPS limits become more a potential issue. There doesn't seem to be much in the news of diversions due to engine failures or problems on long haul flights. Are you aware of any significant diversions that required a twin engine plane to fly on one engine for a couple of hours or more?

Cheers

 

[D747]

ATC can most certainly tell an aircraft to go around, and they can also call for a stop for an aircraft on the take off roll. Dubai issued a stop to a friend flying an Emirates 777 a while back, as a result of a go around on the other runway.

Can I ask the reason why a go around on a different runway would result in a stop? Is it due to separation perhaps?

 

[jb747]

Now that we seem to be moving more and more to big twins rather than four engined jets for long hauls, ETOPS limits become more a potential issue. There doesn't seem to be much in the news of diversions due to engine failures or problems on long haul flights. Are you aware of any significant diversions that required a twin engine plane to fly on one engine for a couple of hours or more?

As far as I know there have never been any real (i.e. other than manufacturers' test flights) shutdowns and diversions that even approach the current ETOPS limits. Engine failures/shutdowns in the cruise phases of a flight are very rare.

.....Seems like a United 777 actually exceeded its 180 minute limit on a flight, actually going for 192 minutes.

I'd expect most diversions these days are caused by failures of 'other' systems...and passenger issues.

Of course, it is a game of playing the odds, and whilst the chance of anything going awry is minimal, it's not zero. The odds are played in most of the rule making, and it's not difficult to come up with scenarios, generally involving multiple or cascading failures, that wouldn't work out in the ETOPS areas.

 

[jb747]

Can I ask the reason why a go around on a different runway would result in a stop? Is it due to separation perhaps?

The runways at Dubai are closely spaced, so it would have to be their expected proximity.

 

[harvyk]

Of course, it is a game of playing the odds, and whilst the chance of anything going awry is minimal, it's not zero. The odds are played in most of the rule making, and it's not difficult to come up with scenarios, generally involving multiple or cascading failures, that wouldn't work out in the ETOPS areas.

Wouldn't those same sorts of issues which could cause both engines to shut down in a twin also cause all 4 engines to shut down in the case of a quad? Or are there potential issues which would be unique to twins which the addition of 2 extra engines mitigates?

 

[jb747]

Wouldn't those same sorts of issues which could cause both engines to shut down in a twin also cause all 4 engines to shut down in the case of a quad? Or are there potential issues which would be unique to twins which the addition of 2 extra engines mitigates?

You're locking on to engines, whereas there are many other systems that can cause grief. A simple part of the equation...lose an engine in a quad, and you will only suffer a fuel burn increase of 10-15%. Lose one on a twin, and you'll end up burning around 30% extra.

Double engine failures, from the cruise, could pretty much only happen with fuel exhaustion or contamination...and I guess it won't matter how many engines you have then.

 

[Awesom Andy]

Double engine failures, from the cruise, could pretty much only happen with fuel exhaustion or contamination...and I guess it won't matter how many engines you have then.

Although in the occasional cases where the "pilots" seemingly like to switch off the wrong engine in an emergency, being in a 4-engine plane would means there are still 2 engines left - 1 failed, 1 switched off incorrectly, 2 functioning. But if they can't follow the checklist the first time round, I'm not confident that the next time will be any better.

 

[JessicaTam]

Although in the occasional cases where the "pilots" seemingly like to switch off the wrong engine in an emergency, being in a 4-engine plane would means there are still 2 engines left - 1 failed, 1 switched off incorrectly, 2 functioning. But if they can't follow the checklist the first time round, I'm not confident that the next time will be any better.

That raises a question that may have been asked (and answered) before - If an engine has been shut down mid flight can it be restarted?

 

[Awesom Andy]

That raises a question that may have been asked (and answered) before - If an engine has been shut down mid flight can it be restarted?

It's definitely possible to start an engine in the air, but I'll leave it to the resident pilots to elaborate.

 

[jb747]

Although in the occasional cases where the "pilots" seemingly like to switch off the wrong engine in an emergency, being in a 4-engine plane would means there are still 2 engines left - 1 failed, 1 switched off incorrectly, 2 functioning. But if they can't follow the checklist the first time round, I'm not confident that the next time will be any better.

If you take your time, there's little danger of shutting down the wrong engine. As I've said many times before, sitting on your hands for a few seconds is the best response to almost every failure.

AvHerald has compiled a list of know events. ASN News » GE235 background: list of wrong engine shut down accidents and ATR-72 engine shut down incidents They aren't common, and it's notable that only one modern twin jet appears on the list, and almost half of the incidents involve the same aircraft type, which possibly says something about its ergonomics, or perhaps the training of the day.