Ask The Pilot

[D747]

Amazing how plans change sometimes...I walked through scheduling on Thursday night to sort out a minor issue from a couple of weeks ago, and I was planning to go home to Melbourne on the 10pm flight. Barely arrived and I was asked if I felt like going to Hong Kong today...so now I'm in HK, and head back tomorrow. All of which means I'll have New Year at home too...almost unheard of.

Good karma for all the great work you do on this site?

 

[Simo]

Glad you got Xmas with your family and also hope you have New Years with your Family as well.

Thanks for you efforts in the Forum.

 

[oz74]

What will NYE involve for you this year jb? Nice to see the rostering gods smiling on you. Have a good one and thanks for all the work you have put into this thread

 

[AVC]

JB, our last flight was in an A330, from BKK, in the pointy end. That would be the pointy end where the tailplane is

Now, as you would expect it was noisy as hell (great for those overnight flights).

The one thing I noticed (apart from it being bumpy) was that every now and then the engine noise would ramp up for maybe half a minute then quieten down. Is this due to the auto throttling?

 

[jb747]

The one thing I noticed (apart from it being bumpy) was that every now and then the engine noise would ramp up for maybe half a minute then quieten down. Is this due to the auto throttling?

The engine power normally doesn't move very much in the cruise. If the increase only happened a couple of times, then it was most likely step climbs.

 

[mjt57]

I was curious that the Captain disconnected the autothrust, and flew the approach using manual thrust. The 380 is really meant to have autothrust engaged at all times...there's no reason to disconnect it, as it does a good job.

When Autothrust is active, what methods or modes of speed control do you have? I noticed that the guys were making adjustments on the panel (such as heading, altitude, etc) for the autopilot. How does autothrust work in relation to this?

Do you simply dial in a speed setpoint for approach and fine tune it as required, or is there other auto functions which control thrust (and therefore airspeed, altitude, etc.)?

 

[jb747]

When Autothrust is active, what methods or modes of speed control do you have? I noticed that the guys were making adjustments on the panel (such as heading, altitude, etc) for the autopilot. How does autothrust work in relation to this?

There are only two things we ever want from the thrust system. Either the thrust to maintain a desired speed, or a particular level of thrust (be it 'climb', 'idle', or a take off setting). The autothrust system works interactively with the autoflight system (which, in manual flight, is simply the flight director), to give an appropriate thrust setting/mode. So, if we select an 'open climb', the autothrust will select 'climb' power. If we select a particular vertical speed (V/S), the autothrust will give the power needed for a given airspeed.

The control being used on the mode panel is the speed dial. When pulled, it opens a window, and allows you to select a given IAS (target for the autothrust). When pushed, the window closes, and the aircraft goes back to 'managed' speed, in which case the speed target is generated by the FMC, and will have been pre-programmed.

Do you simply dial in a speed setpoint for approach and fine tune it as required, or is there other auto functions which control thrust (and therefore airspeed, altitude, etc.)?

Ideally you want the aircraft to be in managed speed. In practice, you're not in managed at all times, but the aim is to get back to it as soon as you can. In managed, during approach, the aircraft automatically slows with each new flap selection. When on final approach, managed will normally be Vref+5 knots. A function called 'ground speed mini' comes into play which automatically, and constantly, adjusts the target IAS to allow for the difference between the current actual wind that the aircraft is experiencing, and the tower reported wind on the ground...that provides some protection against windshear.

 

[Flying Fox]

Hi JB

Merry Christmas & Happy New Year to you and your family.

Wondering when you fly the A380, do you notice significant performance differences when flying a ferry flight vs. a passenger flight?

And if so, can you quantify it for us non-pilots?

Thanks

 

[jb747]

Hi JB

Merry Christmas & Happy New Year to you and your family.

Wondering when you fly the A380, do you notice significant performance differences when flying a ferry flight vs. a passenger flight?

And if so, can you quantify it for us non-pilots?

You probably don't notice weight changes within the normal operating range as much as you might imagine. Between about 400 tonnes and max weight, any weight change is masked by the derate. So, if the aircraft is lighter, we're using less power anyway.

The take off derate stops at 67% (which is about the power you'll use on a departure from Oz to Singapore). Once you get to weights which could give a theoretical derate below that figure, the performance starts to increase. At very light weights (Sydney-Melbourne ferry), the pitch attitude after take off will have increased by about 6-7 degrees, and the rates of climb are very sporting....though not anywhere near what something like a 767 manages.

At the other end of the flight, at light weights the approach speeds are very low (I've seen it go below 120 knots), and the aircraft is very inclined towards floating in the landing.

 

[AVC]

The engine power normally doesn't move very much in the cruise. If the increase only happened a couple of times, then it was most likely step climbs.

My estimate is that it happened at least 10 times. Would any sort of turbulence affect the auto thrust (although it wasn't like a roller coaster ride, more a bumpy car ride. On a dirt road.)

Do the electric jets not use assymetric power during banking or course changes?

As the aircraft gets lighter (from fuel burn off), how is this managed incrementally? Would the aircraft be creeping faster, and then you would climb to to next highest FL that your weight would allow?

Thanks in advance.

 

[jb747]

My estimate is that it happened at least 10 times. Would any sort of turbulence affect the auto thrust (although it wasn't like a roller coaster ride, more a bumpy car ride. On a dirt road.)

Well, you certainly wouldn't do that many steps. Five would be a lot. Normal power changes in the cruise are quite minor, though it can get up there if you're experiencing a few bumps and near the max altitude.

Do the electric jets not use assymetric power during banking or course changes?

Nothing uses asymmetric power...unless you have an engine shut down.

As the aircraft gets lighter (from fuel burn off), how is this managed incrementally? Would the aircraft be creeping faster, and then you would climb to to next highest FL that your weight would allow?

The autothrust always has a target speed, generally provided by the FMC. As it becomes lighter, the target speed is reduced, so the aircraft slows. About the time the speed reduction reaches .02 mach, it then becomes viable to climb to the next step, and the speed goes back to the faster cruise. In the 380 that range is normally .85 reducing to .83. A330 is about .04 (or so) slower.

 

[RooFlyer]

Greetings JB

I am doing a fair bit of flying in Canada at the moment and regularly am on planes that go through the wretched (but necessary!) de-icing routine. I wonder if you've had much experence of it?

Seems to me that given the flight crew can't see much of the surfaces involved, the Captain may yield some of the otherwise total (I think) authority over the plane?

For instance, who decides how much de-icing will be done? (I've experienced 3 broad grades : 'a bit over the wings and tail surfaces'; 'a bit all over' and 'total saturation'.

Who decides that the amount of de-icing done is adequate?

How does the flight crew decide if the plane needs to be re-dosed if there is more than expected time between de-icing and top of the runway for take-off?

Gawd, but the Canadian airline system descends into chaos when normally snow-less Vancouver cops a heavy snow storm, as it did the week before Christmas!

 

[jb747]

I am doing a fair bit of flying in Canada at the moment and regularly am on planes that go through the wretched (but necessary!) de-icing routine. I wonder if you've had much experence of it?

It doesn't come up in our operation very often, but you can see it at just about all levels. London doesn't get much but handles it badly, and Frankfurt has pretty decent snowfalls and ice....though probably Canada can beat them all. I never saw any in my operations to Toronto or Vancouver.

Seems to me that given the flight crew can't see much of the surfaces involved, the Captain may yield some of the otherwise total (I think) authority over the plane?

You're right, we can't see any of it...unless we send someone expendable outside to have a look. It's basically a maintenance function, and will be signed off in the book as such.

For instance, who decides how much de-icing will be done? (I've experienced 3 broad grades : 'a bit over the wings and tail surfaces'; 'a bit all over' and 'total saturation'. Who decides that the amount of de-icing done is adequate?

NO ICE is allowed. So, there really isn't any decision to be made. The deicing crew have to remove ALL of the ice, and the timing will be decided by a table that gives allowed times for the different deicing solutions vs. the actual conditions. It is quite possible that the time from the start will have expired by the time they get to the end...in which case you won't be going anywhere. Something like the 380 is very problematic in that regard.

How does the flight crew decide if the plane needs to be re-dosed if there is more than expected time between de-icing and top of the runway for take-off?

Depending upon the conditions and the deicing fluid being used, we are allowed certain amounts of time...from the start of the deice procedure. Basically, we have to be airborne before that time runs out.

 

[RooFlyer]

Thanks! Scares the willies out of me when there is ice about. I watch them in their cherry-pickers squirting the de-icing fluid over the plane and just hope the guys controlling it aren't new on the job.

I gather the de-icing is just to do that - de-ice already accumulated stuff. Is it supposed to have any preventative function? That is, prevent any accumulation during taxi-ing?

Before Christmas, I was waiting for a plane from YVR to arrive at YYC to take me to YVR for a trans-pac connection. It was 3 hours late arriving. YVR was hit by a large snow storm and the airport never copes with this. Th plane I was waiting for had this sequence at YVR:

* Long wait for de-icing (too few de-icing machines);
* Got the job done, then long delay for take-off;
* Had to go back for de-icing;
* Too long in the de-icing queue; had to go back for fuel before second de-icing accomplished;
* Back to de-icing for third try;
* Got it done, managed to take-off before the whole circus started again.

Crew and pax on board for about 3 hours before actually lifting off.

Moral of the story: Always allow at least 4 hours for connections during winter in Canada!

 

[jb747]

Thanks! Scares the willies out of me when there is ice about. I watch them in their cherry-pickers squirting the de-icing fluid over the plane and just hope the guys controlling it aren't new on the job.

I gather the de-icing is just to do that - de-ice already accumulated stuff. Is it supposed to have any preventative function? That is, prevent any accumulation during taxi-ing?

Only to a small degree. Minutes in any real snow.

Before Christmas, I was waiting for a plane from YVR to arrive at YYC to take me to YVR for a trans-pac connection. It was 3 hours late arriving. YVR was hit by a large snow storm and the airport never copes with this. Th plane I was waiting for had this sequence at YVR:

* Long wait for de-icing (too few de-icing machines);
* Got the job done, then long delay for take-off;
* Had to go back for de-icing;
* Too long in the de-icing queue; had to go back for fuel before second de-icing accomplished;
* Back to de-icing for third try;
* Got it done, managed to take-off before the whole circus started again.

Crew and pax on board for about 3 hours before actually lifting off.

Moral of the story: Always allow at least 4 hours for connections during winter in Canada!

Snow and ice manage to stop most operations.

 

[defurax]

Snow and ice manage to stop most operations.

Except at YUL : 70 Years - No Snow Closure | Team Eagle Ltd. ~ Your Airfield Solutions Partner Amazing airport in winter!!!

 

[jb747]

Well, it sounds like they are more organised than most. On the other hand, there is a difference between keeping the airport open, and being able to deice all of the offered flights.... Snow is disruptive. I guess you'd really expect the Canadians to be better at it than most.

 

[RooFlyer]

Except at YUL : 70 Years - No Snow Closure | Team Eagle Ltd. ~ Your Airfield Solutions Partner Amazing airport in winter!!!

Compare and contrast with Vancouver, where there is a guy with a tank of de-icing fluid and a large water pistol.

 

[MEL_Traveller]

this talk about de-icing reminds me of the story someone told for a (winter) departure ex Melbourne. apparently the captain said the plane needed de-icing, so a tug came, pushed the plane back from the terminal into the sunshine and it it stayed there for 15 minutes until it was ready to leave (dunno how much of that is true or not but it makes a nice story)

 

[Major]

With a strong crosswind, do you anticipate the aircraft movement after rotation and be prepared to provide correction or is it automatic in FBW acft ?

Is landing worse than take off in strong crosswinds or are they both a PITA ?