Ask The Pilot

[jb747]

Let's move away from wake turbulence...whilst still on something similar.

We all hear about aircraft taking lightning strikes, and pictures turn up every now and then. Normally it does little to no damage, though it does require an inspection.

But, what about the thunder? Can a sound be spectacular? It's certainly loud......and is probably responsible for many soiled undies.

 

[Happy Trails]

JB747, there have been a few comments on another thread about living under a flight path.
I live about 10km north east of BKK. Most evenings BA9 passes over, seemingly very fast, loud and low – definitely lower than most other departures. It’s gotten so that I now recognize the noise before I see the aircraft.
An hour or so later QF2 passes by, always higher and quieter, and at what seems to be a more sedate pace. (I’d guess about 50% higher)
Given that they’re similar aircraft on the same route I’m curious as to the different operating regimes. Or maybe it’s just my perception?

 

[serfty]

As for Thunder, on evening last December boarding began 15 minutes early at MEL T2 Gate 16 (?)(in the new 'bit') for my AirNZ flight to AKL. They had changed for the inbound from gate 7 in the hope of reducing taxi time in order to turn arounf before a line of approaching storm activity hit.

The flight was ~50% board when lightning struck the terminal - FLASH!BANG! were virtually concurrent ... certainly some may have soiled ....

In any case the gig was up, and there we sat for 45 minutes until the ramp crew could be activated.

 

[jb747]

JB747, there have been a few comments on another thread about living under a flight path.
I live about 10km north east of BKK. Most evenings BA9 passes over, seemingly very fast, loud and low – definitely lower than most other departures. It’s gotten so that I now recognize the noise before I see the aircraft.
An hour or so later QF2 passes by, always higher and quieter, and at what seems to be a more sedate pace. (I’d guess about 50% higher)
Given that they’re similar aircraft on the same route I’m curious as to the different operating regimes. Or maybe it’s just my perception?

There are a couple of different procedures that can be used when cleaning up a 747. One has cleanup starting at 1000 feet, with the power being reduced from take off to climb when flap 5 is selected. The one that QF use out of Bangkok has the power being reduced from t/o to climb at 1500 feet, with the speed then maintained at V2+10 to 3000 feet, and acceleration and clean up starting then. So, the use of the two different procedures could explain what you see.

 

[jb747]

As for Thunder, on evening last December boarding began 15 minutes early at MEL T2 Gate 16 (?)(in the new 'bit') for my AirNZ flight to AKL. They had changed for the inbound from gate 7 in the hope of reducing taxi time in order to turn arounf before a line of approaching storm activity hit.

The flight was ~50% board when lightning struck the terminal - FLASH!BANG! were virtually concurrent ... certainly some may have soiled ....

In any case the gig was up, and there we sat for 45 minutes until the ramp crew could be activated.

A strike on the aircraft is loud, to say the very least. And I'm sure that everyone on board thinks the jig is up...and then nothing happens.

Leaving Melbourne last week, multiple cells moved through. We were initially delayed by about an hour, and when we were able to ask for a clearance to push ATC wanted us to wait whilst they cleared the backlog. Problem was that we could see the situation arising in which we'd end up stuck at the gate because ground crew were under cover, even though it might be safe enough to take off. For that reason we pushed back and started, but then waited for around an hour before taxying...but it at least meant we didn't need ground crew. It did use some fuel though....

 

[Simo]

A strike on the aircraft is loud, to say the very least. And I'm sure that everyone on board thinks the jig is up...and then nothing happens.

Leaving Melbourne last week, multiple cells moved through. We were initially delayed by about an hour, and when we were able to ask for a clearance to push ATC wanted us to wait whilst they cleared the backlog. Problem was that we could see the situation arising in which we'd end up stuck at the gate because ground crew were under cover, even though it might be safe enough to take off. For that reason we pushed back and started, but then waited for around an hour before taxying...but it at least meant we didn't need ground crew. It did use some fuel though....

How much fuel would the plane use just sitting there idling?

 

[jb747]

How much fuel would the plane use just sitting there idling?

A lot. A 380 is burning about 800 kgs per engine per hour, just sitting there at idle. Normal allowance for taxying out to the runway is 1000 kgs. We used around 5 tonnes the other day.

Longest time I've ever sat on the ground in the queue would be around 5 hours, at New York. In summer when there are thunderstorms around that can become the norm. The laws that the US has enacted to punish the airlines for sitting out there in these queues rather bemuse me. There aren't enough gates for them to sit there..otherwise landing traffic has nowhere to go. But, if after 3 hours somebody wants to get off, the law requires the aircraft to return to the gate if pax request it. Trouble is that means that it will have to join the 'going to the gate queue', which can be every bit as long ... and of course, then it's at the end of the departure queue again.

In London it once took around 6 hours from landing to arriving at the gate...and we had to shut down 3 of the 4 engines, otherwise it might have become cold and dark.

 

[Simo]

A lot. A 380 is burning about 800 kgs per engine per hour, just sitting there at idle. Normal allowance for taxying out to the runway is 1000 kgs. We used around 5 tonnes the other day.

Longest time I've ever sat on the ground in the queue would be around 5 hours, at New York. In summer when there are thunderstorms around that can become the norm. The laws that the US has enacted to punish the airlines for sitting out there in these queues rather bemuse me. There aren't enough gates for them to sit there..otherwise landing traffic has nowhere to go. But, if after 3 hours somebody wants to get off, the law requires the aircraft to return to the gate if pax request it. Trouble is that means that it will have to join the 'going to the gate queue', which can be every bit as long ... and of course, then it's at the end of the departure queue again.

In London it once took around 6 hours from landing to arriving at the gate...and we had to shut down 3 of the 4 engines, otherwise it might have become cold and dark.

That is a long time to just sit there to then have to do a 8 or 10 hour flight.

Do you then run out of flying hours and the rules about how many hours you can fly/work for?

 

[flychrisfly]

Hi

I've seen/noticed that sometimes planes are turned in the air with just the tail rudder resulting in a slow wide turn. When and why is a turn like this used? (I may have it all wrong as it was quite a few years ago.)

Thanks

 

[jb747]

That is a long time to just sit there to then have to do a 8 or 10 hour flight.

Do you then run out of flying hours and the rules about how many hours you can fly/work for?

The hours limits are all part of the equation. That's why it will normally be better to at least be in the queue. But, you can run out, and I've seen many aircraft do just that...so the flight simply becomes a big wait. It's as depressing for us as it is for the passengers. Out of JFK, it's far more relaxing once you're in the air....

 

[jb747]

I've seen/noticed that sometimes planes are turned in the air with just the tail rudder resulting in a slow wide turn. When and why is a turn like this used? (I may have it all wrong as it was quite a few years ago.)

Turns like that are not used at all. The rudder pedals are, for the vast majority of the time, simply foot rests. The rudder is used in crosswinds as we flare, and in engine out cases. The rest of the time very small amounts are used to keep the aircraft balanced...basically pointed where it is going...(and that small amount is generally applied automatically).

If the rudder was used as you suggest, the effect in the cabin would be extremely uncomfortable, as there would be a g loading across the cabin for the duration of the turn.

 

[mjt57]

Turns like that are not used at all. The rudder pedals are, for the vast majority of the time, simply foot rests.

Recently I did a Flight Experience session in a B737 simulator (in Collins St, Melbourne).

Anyway, the instructor said to make a turn to simply "turn the wheel". I asked about rudder control but he said that it wasn't necessary. However, I did use it to make a small heading adjustment when on final. I'm not sure how a real B737 would react, though, but it did make it easier for me to line up the runway.

As for Flight Experience, I loved it. It was only a half hour session and ten minutes of that was being briefed on the controls that I'd be using. Still, I got to take off from JFK, do a circuit and touch and go and fly along the Hudson admiring the scenery and landed at la Guardia.

If I do it next time I'll do MEL to Avalon and back. Or I might fly out to the Valley and see if I can see my house...

 

[jb747]

Recently I did a Flight Experience session in a B737 simulator (in Collins St, Melbourne).

Anyway, the instructor said to make a turn to simply "turn the wheel". I asked about rudder control but he said that it wasn't necessary. However, I did use it to make a small heading adjustment when on final. I'm not sure how a real B737 would react, though, but it did make it easier for me to line up the runway.

The reason that you only 'turn the wheel' is because the aircraft have automatic turn coordination as a function of the yaw damper. You need VERY little rudder in a turn, and the aircraft will take care of it by itself. We put NO rudder in at all, unless we are engine out, and even then it is only necessary any time there is a power change.

Using the rudder unnecessarily makes accurate flying quite a bit harder. These aircraft all have very strong secondary effects from any rudder use....in other words, using the rudder makes them roll.

 

[mjt57]

The reason that you only 'turn the wheel' is because the aircraft have automatic turn coordination as a function of the yaw damper.

That explains it, then.

Hmm, you must be an early riser, or you're not in this time zone. My excuse, I'm at work...

 

[jb747]

That explains it, then.

Hmm, you must be an early riser, or you're not in this time zone. My excuse, I'm at work...

London....

 

[simongr]

New video here: coughpit view A380 YMML departure.mp4 - YouTube

Line up to about FL250.

Thanks for this - I was sat on the tarmac on a 763 (asleep for most of the wait).

 

[QF WP]

Also going back to the MP4 video (brilliant), I remember hearing at 1:44 the announcement "V1", which from the tone of the voice sounds like it was the Airbus "voice" (pity I don't know the right term).

Did I miss the rotate and V2 announcements or were they quieter (I didn't seem to have much audio, had to crank it up to almost full to hear the V1) ?

Enjoy the layover

 

[jb747]

Also going back to the MP4 video (brilliant), I remember hearing at 1:44 the announcement "V1", which from the tone of the voice sounds like it was the Airbus "voice" (pity I don't know the right term).

Did I miss the rotate and V2 announcements or were they quieter (I didn't seem to have much audio, had to crank it up to almost full to hear the V1) ?

The V1 call is automated, but 'rotate' is done by one of us. V2 isn't called at all.

I was a little surprised that there was much audio at all. The little camera sits within a waterproof housing, which isn't all that conducive to sound recording. We also use the intercom system on 'hot mike' at that part of the flight, so we can just about whisper and still be heard clearly by each other.

The sequence of a calls in the video is roughly....
V1
Rotate
Positive climb
Gear up
Runway track
Nav
AP1 on
Thrust de-climb 3, climb, autothrust, flap 1.....

I'm still fiddling with the camera trying to work out the best way to use it (and at this stage I'm a million miles from having the post processing sorted), but the aim by the end of the trip is to get a night take off and landing, and perhaps the departure from London.

 

[QF WP]

That explains it, then.

Hmm, you must be an early riser, or you're not in this time zone. My excuse, I'm at work...

London....

This is jb747's flight movements in February and March, so you'll know if he's posting at OMG o'clock...

 

[QF WP]

Ah good, I'm not going deaf (yet)

I wan't aware of the ones past "gear up" so thanks jb747, a little more knowledge. I always try to imagine where the V1, rotate and V2 points are on the tarmac, but I'm probably waaaay out .

The V1 call is automated, but 'rotate' is done by one of us. V2 isn't called at all.

I was a little surprised that there was much audio at all. The little camera sits within a waterproof housing, which isn't all that conducive to sound recording. We also use the intercom system on 'hot mike' at that part of the flight, so we can just about whisper and still be heard clearly by each other.

The sequence of a calls in the video is roughly....
V1
Rotate
Positive climb
Gear up
Runway track
Nav
AP1 on
Thrust de-climb 3, climb, autothrust, flap 1.....

I'm still fiddling with the camera trying to work out the best way to use it (and at this stage I'm a million miles from having the post processing sorted), but the aim by the end of the trip is to get a night take off and landing, and perhaps the departure from London.

I now have your other YouTube videos to watch...now LHR departure I'm very interested in seeing :mrgreen:.