Ask The Pilot

[jb747]

All this talk of software makes me wonder how you reboot an A380, and where do they hide the any key?

An AT style key...now that is a while back.

When the engineers reboot everything, I think they 'simply' remove all of the power, and then restart from there. It takes about 45-60 minutes, during which time nothing works. And like all computer systems, it can sometimes take a while, or even another go, to get everything back onto the same page.

Sub systems can be rebooted (or reset) by pulling their reset switches (aka circuit breakers). That normally takes a couple of minutes, and some of these can be done in flight. Anything that has an on/off switch can be reset by cycling that switch.

Maybe they use an old AT-style key switch... (Scene: in the A388 coughpit... Hey JB, I just accidentally turned the key past ON to RESET... how long is this thing going to take to reboot)

A couple of systems do show that sort of behaviour. Some of the coughpit display systems can be reset by turning their lighting control through dim to off. Everyone is very careful of that now, but it caught some people out in the early days. Not anything important, or for which their isn't an alternative, but annoying nevertheless.

 

[legroom]

Ask The Pilot

The software is updated, but not all the aircraft are exactly the same hardware, so not all can accept exactly the same software package. Basically, I doubt if two aircraft are ever exactly the same...it's not quite like making a Toyota.

Hi JB,

If so (not all A380s are the same), would you have a preferred 'car' where the settings are just what you like.

In other words, is there any that causes you to say 'she's a rough bird to handle' Vs 'she will give a smooth ride all the way to DXB'?

Resetting the rear view mirror, change the seat position, readjust the power setting etc .....

Thanks

 

[jb747]

If so (not all A380s are the same), would you have a preferred 'car' where the settings are just what you like.

Like a car with memory seats? Jump in, input your staff number, and have the setting go to what you like. Nice party trick, but rather pointless.

In other words, is there any that causes you to say 'she's a rough bird to handle' Vs 'she will give a smooth ride all the way to DXB'?

They all feel exactly the same. That's one of the effects of FBW. The 747 and 767 all had slightly different feels. In particular control column weighting could vary a bit.

Smooth ride..that's the weather, not the aircraft.

 

[AVC]

The other night I was caught on the YouTube cycle, and came across the QF32 incident (a documentary).

Which brought a question to my mind;

The A380 was losing fuel from the wing, naturally. How much fuel, weight wise, is carried in each wing, and how much asymmetrical fuel load could the aircraft withstand before it was unflyable?

Was it the A380 that had no fuel dump whatsoever? That would infer that you couldn't dump the other wing to keep the balance. How was the weight managed?

 

[jb747]

The other night I was caught on the YouTube cycle, and came across the QF32 incident (a documentary).

Which brought a question to my mind;

The A380 was losing fuel from the wing, naturally. How much fuel, weight wise, is carried in each wing, and how much asymmetrical fuel load could the aircraft withstand before it was unflyable?

Was it the A380 that had no fuel dump whatsoever? That would infer that you couldn't dump the other wing to keep the balance. How was the weight managed?

I think the ruptured tank was feed #2, which can hold about 20,000 kgs of fuel (it varies with the specific gravity of the fuel). The normal allowed imbalance for that tank is 3,000 kgs. But, the aircraft has more than enough control authority that a fully empty tank makes no difference to what is felt in the coughpit...the FBW masks it. In the sim I've let that tank drain to zero just to kill the leak.

The fuel system is largely automated, and in this sort of scenario becomes very confused. Sadly, one of the first things that it loses is any ability to dump fuel. I can see why, but don't necessarily agree.

In any similar scenario you may be able to balance fuel by shutting down some of the pumps (whilst ensuring the cross feeds that you want are open). Basically you're simply feeding the running engines from your tanks of choice. With the sort of damage they were dealing with, and the aircraft's relatively benign behaviour with any imbalance, the need to do any balancing at all is minimal.

Total fuel in a wing...potentially up to 120 tonnes on each side. Spread over 12 tanks (that I can think of).

 

[mjt57]

Further to this one... I had a chat with an engineer in Dubai the other day. Apparently on the early A380s, there is a bug in the software that causes the spoilers to rise slightly if both hydraulics systems are depressurised. Apparently only on the ground, and not to a great extent.

How would the software cause that if there's no hydraulic pressure to operate them?

Speaking of which, are all control surfaces, (alerons, rudder, elevators, flaps, slats, etc.) hydraulically actuated? If so, if you lost pressure in flight (I know there are distinct systems with a hydraulic interconnection via a pump arrangement) what would the various control surfaces do?

Is there a failsafe position that they'd move to, say central for rudder, as an example?

 

[jb747]

How would the software cause that if there's no hydraulic pressure to operate them?

Speaking of which, are all control surfaces, (alerons, rudder, elevators, flaps, slats, etc.) hydraulically actuated? If so, if you lost pressure in flight (I know there are distinct systems with a hydraulic interconnection via a pump arrangement) what would the various control surfaces do?

Is there a failsafe position that they'd move to, say central for rudder, as an example?

The A380 has an interesting hydraulic system. Unlike the 747 in which there were four individual systems, all of which were involved in flight controls, or the 767 in which there are three, the 380 has only two, and 5000 psi systems at that. To get the same level of redundancy, there are electro hydraulic actuators all over the place....basically self contained hydraulic actuators that are operated electrically. So, a 380 can loose all of its hydraulics, and yet still be quite flyable.

As to the spoilers, they may well move as the system bleeds down...there's plenty of time and pressure for that.

 

[themanfromoz]

I hope this is a question people will find interesting and informative.
As a result of the recent weather around SE Australia a recent Canberra-Sydney Dash-8 flight was delayed to 'lightning strike within 5km of the airport'.
The ground crew was evacuated from the tarmac (leaving us PAX on the aircraft) even though other staff were running around in vehicles.
Is it airport SOP or airlines SOP that meant the ground staff left us stranded?
So far Canberra airport is blaming airline SOP.

 

[jb747]

I hope this is a question people will find interesting and informative.
As a result of the recent weather around SE Australia a recent Canberra-Sydney Dash-8 flight was delayed to 'lightning strike within 5km of the airport'.

Visible lightning, not necessarily a strike on an aircraft.

The ground crew was evacuated from the tarmac (leaving us PAX on the aircraft) even though other staff were running around in vehicles.

Well, you're safe in the aircraft, as are the staff in ground vehicles. But anybody who was to touch an aircraft whilst being grounded wouldn't be protected...and aircraft are great lightning attractors.

Is it airport SOP or airlines SOP that meant the ground staff left us stranded?

I think you'll find it's OH&S. The rules have been in force for many years.

So far Canberra airport is blaming airline SOP.

Perhaps the airline knows the OH&S rules and the airport doesn't.

This may be the first time you've seen it but it happens at all Australian airports, and delays from this are common. I think you'll find it's also law in the USA, though many Asian countries have a somewhat less concerned attitude.

 

[petercr]

Reminds me of a recent flight my wife was on coming back from MEL - BNE... thunderstorm turned nasty as the plane was coming in over the GC and a number of pax decided that their stomachs didn't like the in-flight catering which resulted in wall-to-wall peas and carrots in a number of rows :shock:.

As the plane was taxying back, there was an anouncement over the terminal PA that ground movements had just gone into lock-down until the storm had passed but I think they managed to bend the rules slightly and get the plane to the gate and get people off...

 

[CaviAck]

Reminds me of a recent flight my wife was on coming back from MEL - BNE... thunderstorm turned nasty as the plane was coming in over the GC and a number of pax decided that their stomachs didn't like the in-flight catering which resulted in wall-to-wall peas and carrots in a number of rows :shock:.

As the plane was taxying back, there was an anouncement over the terminal PA that ground movements had just gone into lock-down until the storm had passed but I think they managed to bend the rules slightly and get the plane to the gate and get people off...

Does the ground movement ban in lightning stop the operation of the aerobridge, and does the plane have to have someone stand in front of it and guide it onto the stop mark? Otherwise can't the plane just park itself, slightly off mark and have the bridge connected and unloadpax without breaking ground movement bans.

 

[jb747]

Reminds me of a recent flight my wife was on coming back from MEL - BNE... thunderstorm turned nasty as the plane was coming in over the GC and a number of pax decided that their stomachs didn't like the in-flight catering which resulted in wall-to-wall peas and carrots in a number of rows

Carrots and peas are always in the mix, no matter what recent meals consisted of. As I'm sure Straightman will attest, one of the great joys of being a RAAF CT4 flying instructor were the cunning roll and pitch manouevres that you employed to ensure that the results of any projectile vomiting stayed on the student's side of the coughpit.

 

[straitman]

Carrots and peas are always in the mix, no matter what recent meals consisted of. As I'm sure Straightman will attest, one of the great joys of being a RAAF CT4 flying instructor were the cunning roll and pitch manouevres that you employed to ensure that the results of any projectile vomiting stayed on the student's side of the coughpit.

At least in a Macchi or PC9 they could catch it in their oxygen mask :!:

 

[ChrisGibbs]

JB747 - over the years flying in what is now the old F cabin section of the 744's, aside from airflow noise, it is a lot quieter than the rest of the cabin so you get to hear a bunch of sounds that would probably otherwise be drowned out by the engine noise in other parts of the cabin. I've wondered about a couple of noises:


- when the gear is retracted you sometimes get a period (normally 5-10 seconds sometimes longer) of vibration coming up through the floor. Does this come from the nose wheel/s still rotating while being retracted? Does the PNF dab the brakes prior to retracting the gear?
- At the point of touch down there is what sounds like an electric motor "whirring" sound that lasts just a couple of seconds. The sound comes from the forward galley area. You also hear the sound again when the aircraft is taxiing off the runway. The only thing I could think of was something to do with the Speedbrakes being extended upon touchdown and then being retracted when the aircraft is taxiing off the runway.

One other question is around the 744 ER's. Apart from the extended range and I presume ZFW, MTOW, etc are their any noticeable differences between the standard 744's and the 744 ER's? It may just be my imagination or just that they are newer than some of the older 744's but the cabin sounds a little quieter when compared to the older 744's.

Thanks in advance.

Chris

 

[QF WP]

Just had this video sent to me by a friend who knows my love of flying. It's a pilots view landing into ZQN: A Pilot (would have rather heard two way chatter than music )

At 2:35 I'd be saying a silent prayer, as all visual references disappear and only-reappear at 3:22 (so I guess it's complete trust in ATC, instruments and experience). jb747, what goes through your mind when you lose spacial awareness and have to rely only on instruments and the crews ability - does it ever get easier the more you do it?

I only realised the speed of the plane at 3:45 (just prior to touchdown) - but can you tell roughly what speed they were doing?

Edit: A great follow up article about the technology (and the person) behind it [[FONT=GE_Serif]digital GPS-based navigation system, called Required Navigation Performance (RNP), first designed by Alaska Airlines pilot Steve Fulton and developed by GE Aviation.][/FONT]

 

[jb747]

JB747 - over the years flying in what is now the old F cabin section of the 744's, aside from airflow noise, it is a lot quieter than the rest of the cabin so you get to hear a bunch of sounds that would probably otherwise be drowned out by the engine noise in other parts of the cabin. I've wondered about a couple of noises:


- when the gear is retracted you sometimes get a period (normally 5-10 seconds sometimes longer) of vibration coming up through the floor. Does this come from the nose wheel/s still rotating while being retracted? Does the PNF dab the brakes prior to retracting the gear?

There's no braking on the nose gear...it just runs down. The main gear is automatically braked as part of the retraction sequence. If a brake is u/s, then the gear has to be left extended for a couple of minutes after take off, which can have some quite extreme penalties associated with it, which is why you don't see it often.

- At the point of touch down there is what sounds like an electric motor "whirring" sound that lasts just a couple of seconds. The sound comes from the forward galley area. You also hear the sound again when the aircraft is taxiing off the runway. The only thing I could think of was something to do with the Speedbrakes being extended upon touchdown and then being retracted when the aircraft is taxiing off the runway.

This one I can't help with..nothing comes to mind.

One other question is around the 744 ER's. Apart from the extended range and I presume ZFW, MTOW, etc are their any noticeable differences between the standard 744's and the 744 ER's? It may just be my imagination or just that they are newer than some of the older 744's but the cabin sounds a little quieter when compared to the older 744's.

They had about another 10 (and potentially 20) tonnes of fuel. Their max take off weight was up around 15 tonnes to (I think) 412 or so. Landing weight was down about 10 tonnes, but that didn't matter in the jumbo as a landing anywhere near max landing weight was a rare event (normally about 20 tonnes under). There were some detail changes in the coughpit, but nothing dramatic. They did feel nicer overall though. Rather a pity the company didn't get more of them at the time. I expect that much of what you couldn't see would have changed to whatever was the current standard...insulation included.

 

[zainman]

Hi JB,

I flew from SYD to CNS the other day in J and there was two QF pilots seated in front of us. I assumed they were QF pilots because their hand carry items had some QF badges etc. These same two pilots (ones in the cabin) then flew us back CNS to SYD the next day and then onward to MEL. (had a 1 hour connection in SYD).

What was their roster like? Why were they flying to CNS just to fly back the plane the next day? Any insight into how the rostering system works would be appreciated! The aircraft was a 767.

 

[jb747]

Just had this video sent to me by a friend who knows my love of flying. It's a pilots view landing into ZQN: A Pilot (would have rather heard two way chatter than music )

As a generalisation, I hate the music that people attach to videos. Silence works....

At 2:35 I'd be saying a silent prayer, as all visual references disappear and only-reappear at 3:22 (so I guess it's complete trust in ATC, instruments and experience). jb747, what goes through your mind when you lose spacial awareness and have to rely only on instruments and the crews ability - does it ever get easier the more you do it?

It's interesting that they're in a turn towards some rocks as they descend into the clouds. The approach is a series of legs and waypoints that are automatically strung together to form GPS based approaches. You're not supposed to make any modifications to them as that will expose you to pilot finger trouble leading you into something solid. This form of approach has really only been available for a short time, but is very rapidly displacing the older VOR and NDB based approaches. In fact, when the ILS to an airfield is out, these can get to a very similar position in the approach, with the only downside being a higher minima. The next step, GLS approaches will take you to the runway, and have the potential to supplant ILS entirely. One was on trial in Sydney for a while, but I don't know of anyone who flew it as it was very restrictive (minima of 2,000 ft, and zero passengers if we wanted to complete the autoland). It will take a while for this to supplant the older technology though, as we'll need a generational change of all of the aircraft. 10 years perhaps.

I've been flying on instruments for so long now that I don't really think about them. I don't lose spatial awareness...I just can't see outside. All that I need is displayed in front of me. Of course, when you're learning it's very different...your inner ear will be sending all sorts of spurious signals, and you must learn to ignore them. It's why so many light aircraft pilots who've self taught get into trouble within about 2 minutes if they ever end up IMC for real. When they've been 'practicing', they still have outside cues, so they never get the inner ear involvement. Real cloud...almost straight away. If they follow what they feel, they lose control almost immediately.

I only realised the speed of the plane at 3:45 (just prior to touchdown) - but can you tell roughly what speed they were doing?

I expect they're fully configured for most of the approach. So, something around 125 knots. Turn radius is obviously important, and being low over that sort of terrain at any speed, especially if not configured for landing, will give rise to GPWS warnings.

 

[jb747]

Hi JB,

I flew from SYD to CNS the other day in J and there was two QF pilots seated in front of us. I assumed they were QF pilots because their hand carry items had some QF badges etc. These same two pilots (ones in the cabin) then flew us back CNS to SYD the next day and then onward to MEL. (had a 1 hour connection in SYD).

What was their roster like? Why were they flying to CNS just to fly back the plane the next day? Any insight into how the rostering system works would be appreciated! The aircraft was a 767.

The company doesn't have you swanning around the countryside if they can possibly avoid it. If they were in uniform it would mean that they had already been flying that day, so they may not have had the available hours to fly the aircraft Cairns. The permutations involved in crew planning are extremely complex. Maximum daily flight time limits, duty limits, minimum rest periods, total hours in a week, a month, a year....all have to be considered.

 

[markis10]

Maximum daily flight time limits, duty limits, minimum rest periods, total hours in a week, a month, a year....all have to be considered.

Not mention people have a habit of picking the wrong day to get sick as an old boss of mine used to say. :shock: