Ask The Pilot

[suze2000]

I'm sure this question has been asked before, but with every single information display reliant on full electronics, are there any old-fashioned dials and gauges in case everything fails? I mean, I work with a lot of equipment that keeps on working even when it appears the computers controlling it are kaput, and I would guess that the same applies to a modern airplane - upon reboot or recovery, everything's chugging along fine, but what happens in the meantime?

 

[jb747]

I'm sure this question has been asked before, but with every single information display reliant on full electronics, are there any old-fashioned dials and gauges in case everything fails? I mean, I work with a lot of equipment that keeps on working even when it appears the computers controlling it are kaput, and I would guess that the same applies to a modern airplane - upon reboot or recovery, everything's chugging along fine, but what happens in the meantime?

Computers that can have any input to the flight control system are never rebooted. If they play up, they are turned off. In the case of the A380, there are six totally separate flight control computers, any one of which can provide all that is needed to fly the aircraft.

Electronics are provided by 4 generators on the engines, another on the APU (there are two, but only can be used in flight). And in the worst case there is an air driven turbine. As failures progress, many of the screens in the coughpit will be sacrificed, ending with just a couple on the Captain's side. Individual failures of screens will result in their contents simply being moved to another screen.

A loss of all electrics, and their backups, would make the aircraft unflyable. But, a short term total failure invokes a seventh, very limited flight control computer, which gets its power from a small generator driven by the hydraulic system. That exists to handle any gap between system failure and backup activation. There is more redundancy than there is in (for instance) a 747.

 

[gaz0303]

Yesterday I was stuck in traffic in a Dash8 waiting for other aircraft to pushback at SYD T3 due to the one in one out limitation of the taxiway. Is there a favourite airport design amongst our pilots that limits this problem? Is there an upside to the SYD T3 setup?

 

[jb747]

Yesterday I was stuck in traffic in a Dash8 waiting for other aircraft to pushback at SYD T3 due to the one in one out limitation of the taxiway. Is there a favourite airport design amongst our pilots that limits this problem? Is there an upside to the SYD T3 setup?

Airports like Sydney, Melbourne, Los Angeles suffer from being old. Virtually nothing about them is efficient. Short of razing them to the ground, and starting again, there's not really a cure. The issues start before you even get inside the airport.

The T3 taxiways are effectively the same as any other finger design...they are always one way. The solution would be to remove the QF hangars...but they need to be somewhere.

Best design? I've not seen anything I consider likely to be a 'best'. Terminals that are effectively islands (London T5, or much of Dubai) probably work quite well, but you need underground access via rail, NO CAR access, and lot of land. I have no faith in Australia ever seeing anything decent.

 

[por930]

jb, when you taxi in, and turn on the APU prior to stopping at the gate, do you leave it running until you get the external power connected, and then shut the APU down? Is the Co policy to always use external power and air conditioning where possible to save fuel and noise from the APU for ground handlers?

 

[jb747]

jb, when you taxi in, and turn on the APU prior to stopping at the gate, do you leave it running until you get the external power connected, and then shut the APU down? Is the Co policy to always use external power and air conditioning where possible to save fuel and noise from the APU for ground handlers?

Funny that you should mention APUs.

The normal deal is to turn it on approaching the gate. Shut down and transfer power and air to the APU. Then when the engineers connect external power to the aircraft, we take that. If there is external air available, shut the APU down after the engineers hook it up. But, as the aircraft are often going to be towed after arrival, it varies from day to day as to whether the engineers actually want us to shut it down or leave it running.

Why is it funny...well, this morning on arrival, the APU had different ideas. It started normally approaching the gate, and initially took the loads as the engines were shut down...but then it decided to auto shutdown itself. That left us without any power, apart from a few batteries. So it went a tad dark in the cabin, and most of the coughpit shut down too. We restarted it, and it took the loads, but just about every computer on the aircraft was still going through a cold restart when we handed over to the engineers. It was, it Douglas Adam's terms, now an SEP.

 

[Captain Halliday]

@jb747 how are you looking for the September Singapore runs, or have you not been to the DAME yet?

 

[jb747]

@jb747 how are you looking for the September Singapore runs, or have you not been to the DAME yet?

The op was delayed by a month, so it looks like I'll be doing them, and perhaps another LA shortly thereafter. Then I'll drop off-line until about November.

The current plan (always open to change), is that I'll do my last trip in about mid February.

 

[Captain Halliday]

The op was delayed by a month, so it looks like I'll be doing them, and perhaps another LA shortly thereafter. Then I'll drop off-line until about November.

The current plan (always open to change), is that I'll do my last trip in about mid February.

Fair enough. I figured I'd miss you on the 35 in Sept either way. Maybe I'll catch you on the 36 on Jan 26. Likely my last chance.

 

[opusman]

Surely we should organise an AFF excursion on JB's last flight

 

[lastrow]

A while ago I watched a SIM demonstration of the ability of an airbus aircraft to correct a stall situation. The instructor deliberately put the aircraft into a stall and then asked the pilot to regain control using normal flying techniques which he failed to do. On the second try the instructor told the pilot to let go of everything and the aircraft will rescue itself.
Can an airbus do this? And Is this something that is included in SIM training ?

 

[jb747]

A while ago I watched a SIM demonstration of the ability of an airbus aircraft to correct a stall situation. The instructor deliberately put the aircraft into a stall and then asked the pilot to regain control using normal flying techniques which he failed to do. On the second try the instructor told the pilot to let go of everything and the aircraft will rescue itself.
Can an airbus do this? And Is this something that is included in SIM training ?

Sim training includes stalling, which we do at high and low level.

Firstly though, in normal law, the aircraft cannot be stalled. If you hold full aft stick it will angle of attack limit at max alpha. Once you leave normal law, it can be stalled just like any other aircraft, but its behaviour is also quite normal too.

So, whilst it would be possible to get the aircraft into such a deep stall that recovery would take so much altitude that you'd run out before recovery, the aircraft cannot recover itself from that situation.

Basically, if you are able to stall it, then whatever smarts the aircraft had, have already been used up.

 

[jb747]

Surely we should organise an AFF excursion on JB's last flight

I might not tell you...

 

[I love to travel]

Are air routes in Australia ever closed because of bad weather. Was on the US East Coast last week and lots of summer storms. Flight from DCA to JFK held at DCA for 3.5 hours because of thunderstorms . We then sat at the beginning of the take off queue for another hour because in our taxi time pilot said they had closed the route.
As an aside about the 55 min mark pilot told FA to give us water. She started to do it then 3 minutes later told to sit down as we were taking off. One minute later take off roll began. Very bizzare

 

[jb747]

Are air routes in Australia ever closed because of bad weather. Was on the US East Coast last week and lots of summer storms. Flight from DCA to JFK held at DCA for 3.5 hours because of thunderstorms . We then sat at the beginning of the take off queue for another hour because in our taxi time pilot said they had closed the route.

No, I’ve never heard of Australian airways being closed, though an airport may be, which will normally result in aircraft being held on the ground.

I think the issue in the USA is that there are so many aircraft, and airports, that it’s pretty much impossible for ATC to manage aircraft when each pilot is making his own decisions about how to avoid patches of weather. So, ATC move or stop, entire streams of aircraft as a management tool. In Oz, there’s plenty of empty sky, and very few destinations.

As an aside about the 55 min mark pilot told FA to give us water. She started to do it then 3 minutes later told to sit down as we were taking off. One minute later take off roll began. Very bizzare

No, it’s a consequence of non aviation people making edicts about passenger ‘care’. Even worse is the ruling about how long people can be held on the aircraft. When it can take hours to get from the gate to the runway, all you need is one person who says they want to get off...then you need to go back to the gate (which could also take hours). It’s effectively a veto on the flight. I know why it was enacted, but it’s poorly thought through, and can have outcomes the opposite of what is wanted.

 

[dxwell]

Can a passenger land a plane? An interesting video 15 minute video - I won't spoil the answer.

 

[QF WP]

Some have - lots of other YouTube videos. I love the interaction between ATC and the “pilots”.

 

[747sp]

I was landing recently in Sydney on a 747 400er and was watching the wing. I noticed that they mostly used the inboard ailerons ( is that the flapperons?) to keep the plane level as we landed. What are the advantages and disadvantages of using inboard ailerons and do you get to choose if you want to use them when flying or is it all automatic?

 

[jb747]

The hurdle that would stop most is actually the very first one. I've been asked this question quite a few times, by cabin crew, over the years. All have the idea that if they can get in touch with someone, then they might have a chance. So, I've simply asked them to select the switch that they will press to call for help. The favourite choice has been the autopilot disconnect.

A passenger with some flying time would have a chance. The more flying time the better. Even some of the gamers would have a fair chance, but in their case only if they could keep the autopilot engaged. I've given a mate who falls into the category of very avid flight simmer a go in the 747-400 sim. I think it's fair to say that he didn't do as well as he'd hoped, but he did somewhat better than I expected.

 

[jb747]

I was landing recently in Sydney on a 747 400er and was watching the wing. I noticed that they mostly used the inboard ailerons ( is that the flapperons?) to keep the plane level as we landed. What are the advantages and disadvantages of using inboard ailerons and do you get to choose if you want to use them when flying or is it all automatic?

In the jumbo, control surface use is mixed automatically, and varies with control column deflection, and IAS.

The manual doesn't provide a great deal of detail, but it has this to say...

Rotating either Control Wheel positions ailerons and spoilers to provide roll control. An aileron lockout system locks the outboard ailerons in the neutral position at high airspeeds and permits full travel of the outboard ailerons at low airspeeds. This prevents overcontrolling at high airspeeds and provides the required roll authority at low airspeeds.

All spoilers, except the inboard spoiler on each wing, function as flight spoilers which operate with the ailerons to provide roll control. Spoiler mixers combine Speedbrake Lever and Control Wheel inputs allowing roll inputs to deflect spoiler panels up or down from their deployed positions when speedbrakes or ground spoilers are in use.

Aileron positions display on the EICAS status display. Separate pointers indicate the inboard and outboard aileron positions on each wing. A full scale deflection of the position indicator corresponds to maximum aileron travel.

The control wheels connect through an override mechanism which allows either wheel to move independently if the other wheel jams and significant manual force is applied to the free wheel. Roll control is then available through the ailerons on the wing corresponding to the free wheel. Approximately half of the flight spoilers are also available for roll control under these conditions.

Each side of the mechanical system also incorporates shearouts which may allow the jammed control wheel to be freed when a significant manual force is applied to the jammed wheel.

I've long forgotten the points at which ailerons are locked out, and I think it varied depending upon then aircraft model (Classic, SP, 400). But, from what little I recall, I expect the outboards are locked out once the flaps are retracted, and above about 230 kias.

Ailerons, whilst giving roll control, also give adverse yaw (i.e. they make the aircraft yaw the wrong way). That's because the downward deflected aileron makes both more lift, and more drag. At high angles of attack, you can actually stall the downward deflected aileron, in which case you'll end up with a roll response in the wrong direction..and is why any response with aileron when learning to stall a light aircraft is such a bad idea. Spoilers used for roll control, always give both correct yaw and roll response...but of course they do spoil some of the lift.