Ask The Pilot

[jb747]

Re: Ask the pilot

Would AF447's outcome have been different if each pilot knew what the others input was.

Most likely. The flying person's input was so appalling that it should have been immediately obvious. I'm surprised that the other guy didn't take it anyway, as he was much more experienced.

 

[mjt57]

Re: Ask the pilot

I probably prefer the sidestick, but I'd like the control laws to be different. If I had the power though, I would change the thrust levers to a 'driven' system.

Could you elaborate on this, please? What is a "driven thrust lever system?

Is it anything like the B737 system? I ask because I had a play in the Flight Experience 737 sim a couple of years ago.

 

[defurax]

Re: Ask the pilot

Quick question on safety. Is having the window shades up in the cabin for take off and landing a country specific requirement? I had a few flights last month in the US with AA, UA and DL and the number of window shades that remained down for the whole flight varied from 10% to 90% (90% was on UA...)

 

[jb747]

Re: Ask the pilot

Could you elaborate on this, please? What is a "driven thrust lever system?

Is it anything like the B737 system? I ask because I had a play in the Flight Experience 737 sim a couple of years ago.

In the Airbus, when the auto thrust is engaged, the levers just sit in the CLB gate, and don't move. In a Boeing, there is a servo that drives the levers, so that they are always in a position that matches the auto thrust setting. So, if you disconnect the A/T, there will be no power change. But, in the AB, you always have to pull the levers out of the gate, and roughly position them before disconnecting the A/T, otherwise, the power will immediately go to CLB. Silly system, but I expect it saves the weight of the servo.

 

[jb747]

Re: Ask the pilot

Quick question on safety. Is having the window shades up in the cabin for take off and landing a country specific requirement? I had a few flights last month in the US with AA, UA and DL and the number of window shades that remained down for the whole flight varied from 10% to 90% (90% was on UA...)

Just about everything is country specific. I think the idea with the shades is that it allows the rescue people to look in, but whether it makes a real difference, I couldn't say.

 

[MEL_Traveller]

Re: Ask the pilot

Just about everything is country specific. I think the idea with the shades is that it allows the rescue people to look in, but whether it makes a real difference, I couldn't say.

another theory is that is allows cabin crew and passengers to be acclimatised to the outside light conditions. Going from darkness to full light, or vv, could cause momentary confusion (as most will attest to if you open the shades during the day to have a peek outside!)

 

[Quickstatus]

Re: Ask the pilot

JB, the first Cabin bell after TO is not "seat belt sign off. What is it for?

 

[jb747]

Re: Ask the pilot

JB, the first Cabin bell after TO is not "seat belt sign off. What is it for?

It's automatic. I didn't even know it existed until recently. It does something useless, like telling the cabin crew that the aircraft is airborne. Basically the air-ground logic switching from ground to air....

 

[Quickstatus]

JB,
assuming an infinitely long R-way.

Will an aircraft like the 747/380 eventually take off without the pilot needing to rotate. If so what would that V be as a proportion of the first decision speed

 

[jb747]

JB,
assuming an infinitely long R-way.

Will an aircraft like the 747/380 eventually take off without the pilot needing to rotate. If so what would that V be as a proportion of the first decision speed

The aircraft would not take off without some form of rotation. On the ground, the pitch attitude is basically 0, whilst in level flight, about the minimum you ever see is 2.5º nose up.

If you accelerated enough, you'd probably reach a point at which the tailplane would generate enough downforce to cause a rotation, but that would be at a speed appreciably higher than the norm, and I have no idea what it might be.

 

[Boris spatsky]

It's automatic. I didn't even know it existed until recently. It does something useless, like telling the cabin crew that the aircraft is airborne. Basically the air-ground logic switching from ground to air....

On some airframes it is manual - after T/O in this instance its an indication from the flightdeck to the cabin crew that they can unstrap and commence cabin duties.

 

[Caversham04]

When flying on SQ's A330's and A380's, it always feels / looks as if the landing roll is quite short, whereas on VA or QF's 737's, there's a lot of noise from the thrust-reversers but it seems to take ages to slow down to taxiing speed. I'm assuming that this is just an illusion as I'd (perhaps simplistically) expect a 737 to need much less runway for landing? Can anyone give estimated landing distances for ADL-SIN (A330), SIN-LHR (A380) and let's say PER-ADL (737)?

 

[jb747]

When flying on SQ's A330's and A380's, it always feels / looks as if the landing roll is quite short, whereas on VA or QF's 737's, there's a lot of noise from the thrust-reversers but it seems to take ages to slow down to taxiing speed. I'm assuming that this is just an illusion as I'd (perhaps simplistically) expect a 737 to need much less runway for landing? Can anyone give estimated landing distances for ADL-SIN (A330), SIN-LHR (A380) and let's say PER-ADL (737)?

Landing distance is, like so many things in aviation, like asking about the length of a piece of string. We never show you a minimum landing distance, but rather the braking is chosen to give us an exit that we want.

Reverse thrust doesn't really do all that much to stop an aircraft. Braking is used simultaneously. Lots of reverse, but a long roll, sounds like a landing on 34L, where you actually want to roll through as far as ATC will let you.

 

[anat0l]

Reverse thrust doesn't really do all that much to stop an aircraft. Braking is used simultaneously. Lots of reverse, but a long roll, sounds like a landing on 34L, where you actually want to roll through as far as ATC will let you.

It must do something enough for it to be used, my guess. Put another way, could you viably dispense of the reverse thrust and just use brakes?

Does the effect of reverse thrust become more significant near the end of landing (i.e. as the aircraft approaches its speed of taxi and exits the runway)?

 

[jb747]

It must do something enough for it to be used, my guess. Put another way, could you viably dispense of the reverse thrust and just use brakes?

It has been discussed many times previously. Largely it cancels the forward thrust that would exist at idle, and it tends to blast water off the runway. The overall negative thrust is very small fraction of forward thrust. Airbus did want to dispense with it entirely on the A380, but was forced to include it (on inner engines only) by the US regulatory authorities.

Does the effect of reverse thrust become more significant near the end of landing (i.e. as the aircraft approaches its speed of taxi and exits the runway)?

No, it's the other way around. It's most effective at high speed. It's generally idle, or even cancelled, by about 70 knots.

 

[mjt57]

Re: Ask the pilot

another theory is that is allows cabin crew and passengers to be acclimatised to the outside light conditions. Going from darkness to full light, or vv, could cause momentary confusion (as most will attest to if you open the shades during the day to have a peek outside!)

I would've thought that having the shades up would give the cabin natural light, thus allowing us to evacuate in light rather than in dark (aside from other theories about looking in, acclimatising, etc.).

 

[mjt57]

Re: Ask the pilot

But, in the AB, you always have to pull the levers out of the gate, and roughly position them before disconnecting the A/T, otherwise, the power will immediately go to CLB.

When going from auto to manual, do you have any indication on where the levers should be positioned? ie. would there be some sort of deviation indication that when reading zero means that the position is balanced? Or is it simply a matter of placing them where you think that it might be then making adjustments afterwards?

 

[straitman]

Re: Ask the pilot

I would've thought that having the shades up would give the cabin natural light, thus allowing us to evacuate in light rather than in dark (aside from other theories about looking in, acclimatising, etc.).

Actually that is a good idea.

In the event of an accident/incident having the shades up allows people to look out and see if there is fire and/or smoke on their side in the event of needing to evacuate the aircraft.

 

[mikenz]

Re: Ask the pilot

Does the max landing weight differ by airport/runway length? Or is it the max weight that the aircraft can safely handle? Or are there limits for both?

Thanks

 

[Boris spatsky]

There is a structural recommended max landing weight but dependant on runway length and missed approach climb gradients you may be more limited than that weight.

Each runway will have a max landing weight which depends on current ambient conditions (temp, barometric pressure), wind, slope, aircraft serviceability (changes if things like anti skid are not working), anti icing on or off, and can be limited a number of ways by, for example, missed approach climb gradient or runway length.

So you may have a max weight for landing on a specific runway, but if the conditions change and you have to use the other end of that runway (the reciprocal), the max weight might be significantly less.