Ask The Pilot

[jb747]

I was watching the procession of take-offs whilst waiting at SYD for my flight on New Year's Day.

The departures were all to the North, across the inner west and then turning as required.

What I did notice was how much flatter the QF A380 take off's were compared to say a CX B777. From my seat, even early in the climb it was obvious the bigger aircraft were in no hurry to gain altitude.

Is that an aircraft type specific thing, an ATC factored thing, or a destination/fuel load governed thing? (or none of the above?)

Pretty much any 380 departure from Sydney, by a 380, will be going a long way, and will be near max take off weight. A CX777 is on a short hop...hardly worth pulling the wheels up.

After take off, power is changed to climb thrust. There are multiple levels of climb thrust available...we normally use the two least powerful ones. I don't know what CX use, but it's likely to be relatively more, especially given their more moderate weight.

Operating on the same long range sector, the 380 will always be able to go higher.

 

[Sprucegoose]

You guys are several thousand feet in the air, in a very 3 dimensional environment, moving very quickly.

That well could be a 4D environment !

 

[jb747]

Wow, fascinating reading.

I'd like your opinion on a few points in that article but perhaps would be much easier to ask in person than type it.. So I'll hold back a bit.

Simple, possibly stupid question but need to ask. When the captain entered the coughpit having not been aware of the indications failing prior to his entry, wouldn't he have seen a massive nose up attitude on the PFD(?), a large rate of descent and stall warnings? Leading to a clear stall indication?? You cannot speak for the man but can you perhaps speculate on his apparent confusion at what I'd (very laymans) consider to be an obvious situation?

You have to remember that the stall warnings were not consistent. They were always accurate, but when the angle of attack became quite extreme, the system stopped believing them, and the warnings stopped. That led to the situation of pushing down, and having the warning return. The attitude and shuddering should have been more than enough warning. I don't think the penny dropped with the others until Bunin said that he'd had back stick in the whole time...but then it was too late.

Why do you suppose Bonin continued with his inputs on his stick after Roberts clearly said "I have control"? His dialogue indicated that due to his lack of understanding about what was happening that he was looking to Roberts (perhaps because of his seniority status) as someone who could help/fix the situation. But when Roberts intervened with the correct input, Bonin simply reversed that input without a word??

I have no idea why Bunin did what he did, and I'm astounded that he pushed the button and locked out the other guy's inputs. He clearly had no idea of what he was doing. In no world does a high nose attitude at altitude make the slightest sense.

This sort of thing should be a non event. Do nothing probably would have worked quite well.

Should there perhaps be some kind of system where pilots are required to fly in conventional aircraft that aren't so automated for a period of time (say x thousand hours) before allowing them into such automated setups to allow them to understand aviation first and machines second? Of course I have no idea how this would be implemented in the real world.

That is pretty much what has been mandated in the USA, but here the vested interests are pushing cadets and MCIR. Cheap tickets don't mate with expensively trained pilots, but that seems a choice that people are happy to make.

 

[ermen]

This was posted in another thread, but it makes interesting reading. I think the translation is most likely not all that accurate, but it certainly touches on many of the hardware factors that we've been talking about.

Should Airplanes Be Flying Themselves? | Vanity Fair

what i don't understand is as a lay person is that couldn't the pilots have just said, screw all this instruments and noise, we are flying this plane manually and try to re-establish control that way?

they seemed to be fixated at maintaining some form of altitude for some reason. in my view, even level flight at 10,000 ft would have made for a better outcome that this.

i guess its easy to criticise as an arm chair person - must have been a very stressful situation out there...

 

[jb747]

what i don't understand is as a lay person is that couldn't the pilots have just said, screw all this instruments and noise, we are flying this plane manually and try to re-establish control that way?

they seemed to be fixated at maintaining some form of altitude for some reason. in my view, even level flight at 10,000 ft would have made for a better outcome that this.

i guess its easy to criticise as an arm chair person - must have been a very stressful situation out there...

I think many of the references to altitude in the article are really talking about pitch (i.e. attitude). I certainly hope so, otherwise almost nothing that was said makes sense.

Screw the instruments...then what else do you have to fly on? You can't fly without them...the problem is deciding which ones are telling lies, and then removing them from your responses.

As for flying manually...when the aircraft reverted to alternate law II at the start of the event, they were flying manually. When that happens the autopilot drops out, and the control laws stop being 'smart'. You just fly it like a Cessna. Sadly, holding back stick (and up to full back stick apparently) is indicative of someone who a) doesn't recognise the situation b) can't fly c) thinks they are still in normal law. Or all three.

 

[flychrisfly]

In a balanced turn (which should be all of them), that's exactly the case. The overall 'g' vector remains perpendicular to the floor.

Assuming level, 1 g flight....as you roll into a turn, the overall amount of lift being made stays the same. But, it is no longer vertical to the ground, so, you can resolve that into two vectors, one perpendicular to the ground, and one towards the centre of the turn. The one towards the centre is what makes the turn happen...but, the component that is vertical is no longer generating sufficient lift for us to maintain level...so we'll need a bit more backside to get a slightly greater angle of attack to make that part of our vectors equal to 1g again. In level turns, the component of lift that is in the vertical must always equal 1g.

If someone talks about a 2g level turn, it means that they have sufficient bank applied for a total of 2g to be needed, but to make that 1g of vertical (60º BTW). As the bank increases, we'll eventually get to a point around. At around 84º of bank you'll hit the 'g' limit for things like the F16...so a level turn beyond that is basically impossible.

A bit more discussion of vectors, and why they are important, here http://www.avweb.com/news/airman/190089-1.html

Thanks JB, to confirm, "a bit more backside" means pitch up/bum down?

So in manual flying, a level bank means both tipping the stick to one side and pulling back a bit? Is this done by feel and is it a case of practice makes perfect?

 

[por930]

I recall some time ago, seeing the TV ad for the airbus A350-900 flying in formation. Here is the clip of the flight being made. A lot of pre-planning and few briefings and they pulled off pretty good in the end. https://www.youtube.com/watch?v=gI4jWYZLeHQ#t=108

How do you think you would go JB or Boris, a fun session?

 

[Boris spatsky]

I recall some time ago, seeing the TV ad for the airbus A350-900 flying in formation. Here is the clip of the flight being made. A lot of pre-planning and few briefings and they pulled off pretty good in the end. https://www.youtube.com/watch?v=gI4jWYZLeHQ#t=108

How do you think you would go JB or Boris, a fun session?

I alluded to this in another post. The basics of formation flying are essentially the same regardless of aircraft type - obviously the larger aircraft have more momentum but ultimately the skill set is similar.

Formation is always fun; but i am not high enough up the food chain to get a look in even if we did do it.

 

[Boris spatsky]

Thanks JB, to confirm, "a bit more backside" means pitch up/bum down?

So in manual flying, a level bank means both tipping the stick to one side and pulling back a bit? Is this done by feel and is it a case of practice makes perfect?

I would suggest this was a typo - 'backstick' intended, rather than backside. But yes, in a level turn you need to increase the backward pressure to maintain level.

 

[jb747]

I would suggest this was a typo - 'backstick' intended, rather than backside. But yes, in a level turn you need to increase the backward pressure to maintain level.

I thought I'd fixed that .... 'damn you autocorrect'.

It's actually more complicated than that.

You need an aileron input to start the roll. The amount of aileron controls the roll rate. As the roll increases, you need to smoothly increase the back pressure (i.e. nose up pitch). You then need to remove the aileron input to stop the roll. But now you have a situation in which the outside wing is following a slightly longer path than the inside, and so must be going slightly faster. As such it will make a little more lift, which has the effect of trying to increase the roll angle. So, in your established turn, a very small amount of aileron has to be carried to counter that.

When you apply aileron, the wing that has the down-going aileron (i.e. the wing you want to go up), will be making a bit more lift than the other. That will cause it to have a little more drag, and that in turn will cause it to yaw in the opposite direction to the roll input. Whilst a small a amount of rudder would correct this, in large aircraft that isn't necessary, as they all have automated rudder input to counter 'dutch roll'.

In part you learn the feel of the amount of control that you need, but mostly it's an exercise in trial and error. You make an input, and then correct it until it gives you what you want. But, because it's such a dynamic environment, that final state will be fleeting.

And in an Airbus...well, at less than 30º angle of bank, you don't need any backstick because it will simply assume you want to be level. So, you simply roll it to where you want, and then let go of the stick. Normally...

Flight control surfaces - Wikipedia, the free encyclopedia

Dutch roll - Wikipedia, the free encyclopedia

 

[Boris spatsky]

It's actually more complicated than that

Ahh yes, i was going for the simplified layman answer

 

[clazman]

How do you think you would go flying a C152 now where you do get any help

 

[jb747]

Ahh yes, i was going for the simplified layman answer

Come on Boris, I'm sure you could add to the complication....

 

[jb747]

How do you think you would go flying a C152 now where you do get any help

Thankfully I've never flown a C152, and I have no intention of changing that. But, if you can find me a CT4 or a Macchi, I'm sure I could suitably embarrass myself in that.

 

[jb747]

I recall some time ago, seeing the TV ad for the airbus A350-900 flying in formation. Here is the clip of the flight being made. A lot of pre-planning and few briefings and they pulled off pretty good in the end. https://www.youtube.com/watch?v=gI4jWYZLeHQ#t=108

How do you think you would go JB or Boris, a fun session?

Formation flying, by a bunch of people who don't do it regularly, is a youtube opportunity in the making. I would most likely be running in the other direction....

 

[clazman]

Macchi jet, worked on them back in 85 at Hawker De havilland, still have a wing bolt as a paper weight on my desk.

Remember sitting in the back as they tested the engine after the rebuild... wow thought we were going to go VSTOL on the chocks.

 

[mjt57]

Thankfully I've never flown a C152, .

Why is that (the "thankfully" bit)?

 

[jb747]

Why is that (the "thankfully" bit)?

Rather like cars...some I'd like a drive of, others I'd rather not.

 

[FlyboyAl]

For JB and Borris - do you guys actually know each other? As in coffee together in the staff canteen so to speak?

 

[Dmac6345]

Hi Pilots,
As flying into/around storms is a hot topic at the moment, I have a couple of questions.
Has there been a time when the current (flying) weather conditions have worried (scared/concerned) you as the captain?
Is there a time when things could potentialy get that bad, that you need to turnaround and head back home?
Thanks for your time with answering any questions on this thread. It is just awesome!