Ask The Pilot

[anat0l]

Another switch to recall when busy. There are various pros and cons to this...but I'd have to admit that I belong to the anti camp. Many things are said which would worry people without the appropriate knowledge, or context.

It was United Airlines that had this feature. I believe it is (was) channel 9.

Many people (obviously avgeeks and FTers) are quite vehement subscribers to this channel. When some plans to get rid of channel 9 were floated, you can imagine the reaction. (And no, it was not a mass order placed for tiny violins).

There's a weight criteria, which I can't recall, but basically 767 and up, with the 757 also included, even though it is below the nominal weight. The 380 is 'super'...though I'd prefer 'fatso'.

I'm sure ATC would get a crack out of that.

(Of course, I think Australia would be the only place you could ever pull off something like that)

 

[markis10]

Another switch to recall when busy. There are various pros and cons to this...but I'd have to admit that I belong to the anti camp. Many things are said which would worry people without the appropriate knowledge, or context.



There's a weight criteria, which I can't recall, but basically 767 and up, with the 757 also included, even though it is below the nominal weight. The 380 is 'super'...though I'd prefer 'fatso'.

ICAO designation:

• Light – MTOW of 7,000 kilograms (15,000 lb) or less;
• Medium – MTOW of greater than 7,000 kilograms, but less than 136,000 kilograms (300,000 lb);
• Heavy – MTOW of 136,000 kilograms or greater.

FAA uses their own:

• Super - A380
• Heavy - Aircraft capable of takeoff weights of 300,000 pounds (140,000 kg) or more whether or not they are operating at this weight during a particular phase of flight.
• Large - Aircraft of more than 41,000 pounds (19,000 kg), maximum certificated takeoff weight, up to but not including 300,000 pounds (140,000 kg) .
• Small – Aircraft of 41,000 pounds or less maximum certificated takeoff weight.

Ref ICAO Doc 8643

 

[harvyk]

This is probably something that is unique to Microsoft Flight Sim, however every so often the "ATC" comes on and states there is a plane of type at say 9'oclock within 4 miles and then asks the "pilot" to confirm visual contact (really difficult when the plane is at say 7o'clock and thus you can't see it). I would imagine this is something which MS has taken some artistic license in doing? (As a side note "ATC" does nothing to try and move planes away from each other, it just gets more and more frantic asking if you can see the other plane)

In real life if two planes are within a certain distance of each other, what is ATC likely to say? I'd imagine ATC would state the course of action they would like the planes to take, would they advise the two planes their distance apart? (Obviously ATC would do everything they could to stop this situation from happening in the first place).

 

[jb747]

I'm sure ATC would get a crack out of that.

(Of course, I think Australia would be the only place you could ever pull off something like that)

The UK controllers have a sense of humour, and they can be extremely quick with a response.

One story from years ago, (and like all such stories, probably apocryphal)....Air India on arrival is told, 'I need you to lose a minute, just do an orbit in present position'. AI responds with...'ah but if I do an orbit, I'll lose two minutes'. To which ATC come back with...'ok, well do a 180, and come in backwards'.

 

[anat0l]

I got asked this question by my sister recently and I didn't know how to answer it:

What is the speed of an aircraft (let's say A380) as it takes off? And what is its speed as it touches down?

I realise there must be some environmental conditions factored into that, plus things like load etc.



Also, what kinds of major factors can affect the length of the take off roll (I hope I used that term correctly: the length of runway traversed before an aircraft lifts off the ground)?

 

[markis10]

This is probably something that is unique to Microsoft Flight Sim, however every so often the "ATC" comes on and states there is a plane of type at say 9'oclock within 4 miles and then asks the "pilot" to confirm visual contact (really difficult when the plane is at say 7o'clock and thus you can't see it). I would imagine this is something which MS has taken some artistic license in doing? (As a side note "ATC" does nothing to try and move planes away from each other, it just gets more and more frantic asking if you can see the other plane).

Getting a pilot to report sighting another aircraft is often used as a method of separation - visual separation, often followed by an instruction, for instance, Behind the Beluga on short final, line up!

In the case of Tower separation, generally this is only done when the tower is in sight of both, when the lead aircraft is not a 757 and wake turbulence separation is not required, it can also be done enroute for traffic below FL180, however the 757 requirement does not apply in this case.

Sometimes pilots will be asked to report sighting and passing traffic before a clearance to change levels is given, this negates any procedural hold in place for routes that dont have radar coverage, allowing quicker facilitation of pilots requests whilst maintaining separation.

 

[harvyk]

Is this method of separation used above FL180?

 

[markis10]

Is this method of separation used above FL180?

Only sighting and passing AFAIK, breaking the procedural constraints on the traffic that can be quite conservative. Its based on common sense, you cannot hit something that is travelling away from you.

 

[jb747]

I got asked this question by my sister recently and I didn't know how to answer it:

What is the speed of an aircraft (let's say A380) as it takes off? And what is its speed as it touches down?

I realise there must be some environmental conditions factored into that, plus things like load etc.

The numbers vary enormously. For an A380, and using Singapore 02L (4000 metres) (nil wind, 25C, 1013 mb)
569 tonnes:
V1 = 136 kts
Vr = 161 kts
V2 = 167 kts
Flex 38
Flaps 2

But, if I use Flaps 1+F
V1 = 139
Vr = 164
V2 = 171
Flex 39
Flaps 1+F

Same weight (and weather) out of LAX 24L
Can't do it with that weather and weight...so
Packs off

V1 = 136
Vr = 155
V2 = 163
Flaps 2
TOGA

Alternatively with packs on and flap 3
V1 = 135
Vr = 150
V2 = 158
Flaps 3
TOGA

Today, out of Melbourne to Singapore the weight will be about 455 tonnes
So, actual current conditions (hot, light southerly)
V1 = 130
Vr = 153
V2 = 158
Flex 65
Flaps 2

In days past, V2, was an engine out safety speed, but these days, the aircraft performance is such that a range of speeds are available that will give the performance results that are needed.
V1, is the first speed at which the option to continue the take off with an engine out becomes available, and it is also used as the refusal speed.
Vr is the speed at which you initiate rotation, with the aim of achieving V2 at 35 feet. At light weights V1 and Vr may be equal.

Because modern aircraft invariably employ derating (in our case up to 33% of the available power), runway distance used isn't much of an indication of the aircraft weight or performance. We'll use about the same today at 455 tonnes as we would at 569, but we'll do so with much less power, an lower target airspeeds.

On approach:
If you were forced to land immediately after take off, and hadn't dumped any fuel, say..
565 tonnes Vapp = 169 knots
391 tonnes (MLW) Vapp = 143 knots
365 tonnes (normal) Vapp = 139 knots

From what I remember, the 747 numbers are all 5-10 knots higher.

Also, what kinds of major factors can affect the length of the take off roll (I hope I used that term correctly: the length of runway traversed before an aircraft lifts off the ground)?

Weight, wind, temperature, elevation, flap setting, derate, anti ice, packs, runway condition....and so on.

 

[harvyk]

JB, do you simply trust what the FMC tells you based on the data you've entered in regards to weights? Or do you still sit down with pen and paper (or at least a calculator \ previous knowledge in similar conditions) and work out the speeds yourself?

Also how often would you press the TOGA button, as appose to manually opening the throttle?

 

[moa999]

jb747,
Some interesting posts here on fuel cost, fuel burn etc.

As a question from a pure 'efficiency' point of view, if fuel keeps going up do you see a potential return to multi-hop flights even if for a quick splah'n'go.
Obviously this would need to be counterbalanced by the extra cost (maintenance mostly I assume) from an extra landing/takeoff cycle.
eg. A380 flying SYD-HNL-LAX with a landing, taxi to a remote fueling station, then quick return for takeoff

--

PS. As you head off on QF31 tomorrow say hello if you get a chance to the QF127 pilots who will be winging me to HKG... Have you flown this route yet or does LHR remain the preferred?

 

[rechoboam]

Another switch to recall when busy. There are various pros and cons to this...but I'd have to admit that I belong to the anti camp. Many things are said which would worry people without the appropriate knowledge, or context.



There's a weight criteria, which I can't recall, but basically 767 and up, with the 757 also included, even though it is below the nominal weight. The 380 is 'super'...though I'd prefer 'fatso'.

Talking about avgeeks...my simulator has this button on the 737.

 

[jb747]

JB, do you simply trust what the FMC tells you based on the data you've entered in regards to weights? Or do you still sit down with pen and paper (or at least a calculator \ previous knowledge in similar conditions) and work out the speeds yourself?

Also how often would you press the TOGA button, as appose to manually opening the throttle?

The FMC doesn't calculate the TO data, though it does work out the approach speed, but then that's just a function of weight. TO calculations are done on what we call the OIT, which is a separate computer system run by a couple of laptops. That's the only way we can work out the data...there are no paper performance graphs at all.

There is no TOGA button in the Airbus. The thrust levers have a number of gates, the forward most one is TOGA...so the levers are always pushed to that position if you want TOGA. Most take offs are at the next level down...FLEX/MCT.

On the 747-400, the levers are pushed up to about 25% (I forget the exact number), and when stabilised, the TOGA button (which is on the thrust levers) is pushed and then the autothrottle will take the levers up to the preset power. Once it reaches that position, power is removed from the lever servo (to stop any further movement). If we want more power, we can just push the lever further forwards. As long as it is serviceable, the autothrottle is always used for TO. On landing most disconnect it at the same time they disengage the autopilot.

On the 380, the autothrottle is always used, from start of take off roll to the flare, whether flying manually or not.

 

[jb747]

As a question from a pure 'efficiency' point of view, if fuel keeps going up do you see a potential return to multi-hop flights even if for a quick splah'n'go.
Obviously this would need to be counterbalanced by the extra cost (maintenance mostly I assume) from an extra landing/takeoff cycle.
eg. A380 flying SYD-HNL-LAX with a landing, taxi to a remote fueling station, then quick return for takeoff

Whilst multi hop may use less fuel, and offer more payload, I doubt that the passengers would be interested, and the landing fees and other costs would offset any gain.

As you head off on QF31 tomorrow say hello if you get a chance to the QF127 pilots who will be winging me to HKG... Have you flown this route yet or does LHR remain the preferred?

Change of plan. I swapped that trip for another, and am now operating a day earlier...and on the 9 ex Melbourne. So, we got the joy of being delayed by this afternoon's thunderstorms.

 

[simongr]

So, we got the joy of being delayed by this afternoon's thunderstorms.

You and me both...

 

[jb747]

You and me both...

I've got a GoPro video of the entire departure, from push back to reaching a nice blue sky. When I've got it edited, and reduced in size to something reasonable, I'll add it to the youtube site.

 

[el_rooto]

Why do the cabin lights get dimmed/turned off before landing?

 

[jb747]

Why do the cabin lights get dimmed/turned off before landing?

Well, I think the general theory is that it means your eyes might be better adjusted to the darkness that could ensue if something goes wrong. Possibly it just seems like a good idea (at the time).....

 

[anat0l]

Well, I think the general theory is that it means your eyes might be better adjusted to the darkness that could ensue if something goes wrong. Possibly it just seems like a good idea (at the time).....

As a little kid we used to fly to Malaysia every year to see my mum's family. This consisted of usually a 747/777/330 flight from BNE to KUL, then a 737 flight from KUL to KBR.

When I was small I can never remember the BNE-KUL flights having the lights dimmed before take off, but on the KUL-KBR flights I could clearly remember it.

My mum used to tell me that the lights were dimmed on the 737 to save power that might be needed.


Sounds like it wasn't that true, but it was plausible enough when I was a little kid.

 

[harvyk]

Whilst I suspect I already know the answer to this one, it would be nice to get a pilots validation.

Do military aircraft always take off with full fuel tanks, or do they take off with only enough fuel to cover the mission at hand (plus standard reserves)?