Ask The Pilot

[jb747]

JB, how much time is there to react to something like this? Avherald does make it seem like there was very little margin to act with that one

The abort/go decision has to be literally instant. You don't have time to think about it. Just think of it as black and white...normal or not. If it crosses your mind, then you need to do something.

Looking at the numbers for the incident aircraft, its Vr was only a couple knots above V1, and V2 was only five more.... (137, 139, 144).

Vr, is the speed at which we start to rotate the nose (i.e. apply back stick), with the aim of achieving V2+10 at 50 feet. Vr is a minimum of 110% of the stall speed (and in this instance about 15%), so in this instance the aircraft was above the stall speed even when the wind change kicked in. Issues would be getting it airborne before the end of the runway, whilst simultaneously avoiding the tail scrape, which would be extremely easy to do in the circumstances.

 

[Duffa]

Over the years I've seen some pretty interesting behaviour with regard to people pushing on in very suspect conditions.

I've diverted from London (to Amsterdam) when another airline (that many of you like) most definitely landed outside of the Boeing designated limits. We treat limits as absolute, whereas they consider themselves to be at least as good as the Boeing test pilots, and so consider them advisory only. In HK I taxied away from the runway and back to the terminal, having decided that I would not take off, only to see another airline go...and they'd recently lost an aircraft in similar conditions.

My employer has always relied on their Captains to make valid calls as to the safety of an operation, and there is no come back whatsoever at any safety based decision. Others either don't have that discretion, or don't use it. Some of the hiring practices now in use (i.e. using third party companies to supply pilots) makes it very easy to bring undue pressure to bear. That's something that a mature operation won't do, but I see plenty around that vary from cranky two year olds, to sulky teenagers...

+1 to that jb747!
I'll never forget being diverted to coughet from Singapore due to thunderstorm, while on a QF flight from London.
We landed, took on a bit of fuel and set off for SIN. Three hours later, landing as smooth as a baby's bum.
And I remember thinking (whilst overhearing the "I'll miss my connection" whingers) that a big wind shear on short final could have meant that we'd all miss our next flight!!
I hate these gung-ho pilots who think they have to get there at all costs!

Duffa

 

[Duffa]

p.s. The real reason I'm on this thread is to ask why you always have sheepskin covers over your lovely leather/designer fabric seats. They always look so mingin, with all the fur in clumps, like when our Shizu needs a wash.
I had been reading the "J* gets the 787" thread and clicked through to Wiki and got a shot of the ANA 787 flight deck - sheepskin seats!
Then I remembered the news from earlier today and the shot of pup Clarke in a QF A380 coughpit and yep, sheepskin on the seats again!

What's the story?

 

[jukebox333]

JB - another question for the heart, not the head (!).

When you made the transition from military to civil aviation, were you consciously aware that you were piloting an aircraft with xx_ souls aboard, and you were responsible for thier safety?

The other day I was thinking about the drive home from the hospital with my son after he was born - thirteen years ago - I had been driving passengers around in cars since I was 17, but that very first drive with a three day old baby, I was a lot more conscious of the responsibility - and I wondered if there was an equivalent feeling for a pilot on his first commercial flight?

I assume that, just like me driving the car, you eventually are less actively aware of that feeling of people's lives being in your hands, but I did wonder if it was a bit different when you first started.

 

[jb747]

p.s. The real reason I'm on this thread is to ask why you always have sheepskin covers over your lovely leather/designer fabric seats. They always look so mingin, with all the fur in clumps, like when our Shizu needs a wash.
I had been reading the "J* gets the 787" thread and clicked through to Wiki and got a shot of the ANA 787 flight deck - sheepskin seats!
Then I remembered the news from earlier today and the shot of pup Clarke in a QF A380 coughpit and yep, sheepskin on the seats again!

Our aircraft have all had woollen seat covers for at least the last 30 years. Comfortable, don't get wet when you're really working, and last way better than leather. Not slippery either.

 

[jb747]

When you made the transition from military to civil aviation, were you consciously aware that you were piloting an aircraft with xx_ souls aboard, and you were responsible for thier safety?

I assume that, just like me driving the car, you eventually are less actively aware of that feeling of people's lives being in your hands, but I did wonder if it was a bit different when you first started.

I don't recall ever being that aware of the passengers. In the early days you have far too much else on your plate, and when old and grey you're used to it.

 

[harvyk]

When adjusting the flaps, do they start moving as the lever moves past the position, or only once it is locked into place. For example say your at 10, and you move the lever down to 25 going straight past 20. Would the flaps start moving to 20 deg as the lever is going past, or would they only start moving when the lever gets placed at 25.

 

[jb747]

When adjusting the flaps, do they start moving as the lever moves past the position, or only once it is locked into place. For example say your at 10, and you move the lever down to 25 going straight past 20. Would the flaps start moving to 20 deg as the lever is going past, or would they only start moving when the lever gets placed at 25.

Neither the Boeing or Airbus manuals are all that definite about exactly how the selections work, and in operational terms, we don't greatly care. But, the modern aircraft selectors are basically copies of the flap selectors that existed in older aircraft. I think you'll find that each of the gates is actually a switch, that sends the message to the control unit, which itself sorts out the sequencing.

In past aircraft that I've flown the selector has been more of a rheostat, with a couple of notches for particular positions, so intermediate positions could be selected (this was useful when dogfighting in the A4).

 

[Major]

After boring holes in the sky over Toowoomba last night for nearly an hour I was wondering about holding patterns.
Are they manually flown or is there a programme which is flown by the auto pilot ?
We started at about 8800m but were down to about 6600m before joining the finals queue, at what intervals would ATC descend the aircraft ?

 

[jb747]

After boring holes in the sky over Toowoomba last night for nearly an hour I was wondering about holding patterns.
Are they manually flown or is there a programme which is flown by the auto pilot ?

In the electric jets (which is pretty much all of them now), the FMC controls the autopilot to give you automatic holding patterns. The patterns themselves have to be programmed (speed, time, direction, and inbound or outbound from the fix).

We started at about 8800m but were down to about 6600m before joining the finals queue, at what intervals would ATC descend the aircraft ?

The aircraft would be spaced 1000 feet apart in the holding pattern.

There would almost certainly have been more than one holding point in use. ATC's aim, apart from running you out of fuel, is to build a sequence that allows arrivals to end up spaced about 5 miles apart.

 

[Bjet]

Which base do u stay? Sydney? If you moved to Perth and wanted Perth as your new base, you're supposed to fly with B744 but it doesnt stay in or fly to Perth (international only). It means that you have to fly to Sydney and Sydney is still your base? right?

 

[drpurpleturtle]

Hey JB,

Probably a stupid question, but in regards to in-seat power onboard I was wondering where it actually comes from (fuel or a dedicated generator)?

Thanks in advance.

 

[jb747]

Probably a stupid question, but in regards to in-seat power onboard I was wondering where it actually comes from (fuel or a dedicated generator)?

It comes from the various utility buses, which are powered by the main generators (which are in turn powered by the engines).

 

[wafliron]

Apologies that this is a little OT for the thread, but I figure the "target audience" is about right (and failing that, I'll claim it dovetails with the discussion about stalls ~20 (?) pages back ;-)):

I just watched the Megafactories episode about LearJet, and found the section where the test pilots deliberately stall the plane very interesting to watch - particularly because it shows both coughpit and external (from a spotter plane) views of what follows. There's a fair chance that the director hammed it up a bit in the edit suite, but I found seeing both the rate at which the plane starts losing altitude and the magnitude of the control inputs needed to recover from the stall both surprising and interesting.

If anyone else is interested, watch http://youtu.be/tqVW_TunVmM?t=35m55s starting at about 36:00 (which is pre-set in the link).

 

[jb747]

There's a fair chance that the director hammed it up a bit in the edit suite, but I found seeing both the rate at which the plane starts losing altitude and the magnitude of the control inputs needed to recover from the stall both surprising and interesting.

Whilst the large roll inputs don't fit with stall testing and are probably the director, stalling may well involve full control deflection... Stalling, per se, is no big deal at all. It simply means we're attempting to use more lift than we can generate. The fighter guys live on the boundary between stalled and unstalled, no matter how fast they're going....it's an angle of attack thing, not solely based on speed.

Of course, airliners, don't live there, but it should be something that both the aircraft and the pilots just handle.

 

[wafliron]

Whilst the large roll inputs don't fit with stall testing and are probably the director, stalling may well involve full control deflection...

Thanks for clarifying re the extent of the director's "artistic license" - that said, there are one or two shots where the pilot is applying a large roll input and you can also the airspeed indicator is "in the red", so perhaps he didn't entirely"make it up"? Or perhaps it is "real" footage of a stall recovery, but the director asked the pilots to ham it up a bit.

 

[jb747]

Thanks for clarifying re the extent of the director's "artistic license" - that said, there are one or two shots where the pilot is applying a large roll input and you can also the airspeed indicator is "in the red", so perhaps he didn't entirely"make it up"? Or perhaps it is "real" footage of a stall recovery, but the director asked the pilots to ham it up a bit.

Roll inputs normally result in one aileron deflecting down, and the other up (there are other ways it can be done with spoilers). The down going aileron gives the wing at that point more curvature, and will result in that section of the wing having a lower stalling angle of attack. So, using aileron around the stall angle can cause local stalling of the wing with the down going aileron, which actually results in both increased drag and reduced lift...so the roll effect is the opposite to what you've input. It's actually a way of causing a spin entry.

If you've stalled an aircraft, the recovery involves reducing the angle of attack, by pushing forward. Using any roll control at all is a no no. You can fix any roll diversions AFTER the aircraft is unstalled.

 

[Fruitcake]

jb747, prior to the days of simulators was entry into a "full" stall part of the training program for everyday airliners pilots? Or does training focus on avoiding them, and actual stalls left to certification?

 

[jb747]

jb747, prior to the days of simulators was entry into a "full" stall part of the training program for everyday airliners pilots? Or does training focus on avoiding them, and actual stalls left to certification?

I don't date back that far, but simulators have been around for a very long time. I recall having a go in the QF 707 sim back in the 70s.

I very much doubt that the big aircraft are ever stalled, even by the development test pilots. It's unlikely to prove anything other than how fragile things can be. Even in the full motion sims, we recover at the first sign of a stall, and that's normally the stall warning, which actually precedes the stall itself.

 

[HW]

I very much doubt that the big aircraft are ever stalled, even by the development test pilots. It's unlikely to prove anything other than how fragile things can be.

Boeing 787 Stall Tests - YouTube talks about 787 stall testing. There are some 747 stall test videos kicking around also that are more dramatic.