Ask The Pilot

[jb747]

Another quick one if I may... I came across this photo on Twitter. https://twitter.com/coughpitChatter/status/419396421901484032/photo/1/large

It's pretty obviously what's wrong in that photo! Wouldn't there be some notification on the flight deck that the 1R door handle is in that position? Would this pose any issue for the aircraft in flight? I'm assuming not as there obviously hasn't been anything in the news about a mishap with this airline, but I was just curious. I've never seen anything like that before!

As long as it's locked from the inside, then it's locked. Might be some noise or vibration from the door, but that would be the extent of it.

 

[petercr]

They're a bit like your old favourite shoes. Replaced the uppers twice, and the soles three times, but still the same shoes.

Hasn't it been oft-quoted that some H-model B52's that are still in service are older than even some of the senior flight crew who fly them?

 

[markis10]

Hasn't it been oft-quoted that some H-model B52's that are still in service are older than even some of the senior flight crew who fly them?

Would not be hard considering production was 1952-1962, and they will be in service until 2040.

 

[mjt57]

On the ground it's relevant when taxying around. Many places have speed limits, and in Dubai there's even a guy with a radar gun.

What sort of limits are we talking about here and what penalties are applied (and to whom)?

Do they give you any leeway?

 

[jb747]

What sort of limits are we talking about here and what penalties are applied (and to whom)?

Do they give you any leeway?

Probably leeway everywhere except Melbourne....

There's only the one place I've ever heard of where they measure the speed. Don't know what enforcement action they take, but as it's in an area where I'm only going at about 8-10 knots, and the limit is 20, I'm hopefully never going to find out.

There was a signposted limit on the two bridges that cross over the entrance road at Singapore... As it was uphill, it was hard to have any speed at all, much less hit a limit.

 

[SeatBackForward]

JB,

I've read that the A380 tyres are inflated with nitrogen. Is this for weight reasons?

 

[sydstar]

Hi JB, thanks for a great thread!

What generally happens to pilots when a particular aircraft is 'retired' from the fleet? I'm thinking of the 767 here; are pilots 'encouraged' onto other types, or do they effectively become redundant? Am I correct in thinking that a lot of the 380 crew who were 747 went 747 to 380 (via the 330) thinking of the long term?

 

[jb747]

I've read that the A380 tyres are inflated with nitrogen. Is this for weight reasons?

I think it's a combination of the way it isn't reactive, and also because it tends to leak out more slowly.

 

[jb747]

What generally happens to pilots when a particular aircraft is 'retired' from the fleet? I'm thinking of the 767 here; are pilots 'encouraged' onto other types, or do they effectively become redundant? Am I correct in thinking that a lot of the 380 crew who were 747 went 747 to 380 (via the 330) thinking of the long term?

In the normal course of events, the aircraft you're on would have some form of replacement, and you'd go there. Many of the early 380 people came straight from the 747 Classic, as that aircraft was retired. The route via the 330 was only used for the the introduction.

Contract-wise, it's quite possible that the orphaned 747 & 767 people could displace pilots from other fleets.

 

[legroom]

If you're trying to defend against a warning system that doesn't work, then the only real defence would be to wear a mask at all times. But, really, we're just as reliant on those warning systems for everything (i.e. smoke, fire, etc). They're generally duplicated in some way, so as long as you actually respond to the warning, and don't sit and wonder what it means, you shouldn't have too many issues.

Being surrounded by information numbs you to it. A warning system will pick out the changes better than a person can.

Worth remembering that the 'time of useful consciousness' at FL400 is measured in seconds.

Hi JB,

It's alarming to know that the effects of hypoxia at altitude are measured in seconds, not even minutes.

I wonder if you have ever put on an O2 mask in response to a hunch, some symptoms or due to a false warning light... only to remove it afterwards.

Better be safe than wrong, so to speak given the very short period of impending loss of consciousness.

TUC (time to unconsciousness) according to ATSB

Table 1: TUC at various altitudes[1]

Altitude (Feet)	Standard Unpressurised Ascent Rate (minutes and seconds)	After Rapid Decompression (minutes and seconds)
18,000	20 to 30 minutes	10 to 15 minutes
22,000	10 minutes	5 minutes
25,000	3 to 5 minutes	1.5 to 3.5 minutes
28,000	2.5 to 3 minutes	1.25 to 1.5 minutes
30,000	1 to 2 minutes	30 to 60 seconds
35,000	30 to 60 seconds	15 to 30 seconds
40,000	15 to 20 seconds	7 to 10 seconds
43,000	9 to 12 seconds	5 seconds
50,000	9 to 12 seconds	5 seconds

---

[1] FAA Advisory Circular AC No: 61-107A, titled Operations of aircraft at altitudes above 25,000 feet MSL and/or MACH numbers (M[SUB]mo[/SUB]) greater than .75. 2 January 2003, page 11 paragraph f, Table 1-1.


Also, a little off this topic, if I may.

What sort of warnings during flight that would make you immediately sit up and take control from the FO (or the FO has to call for you ASAP) ?

Thanks

 

[jb747]

It's alarming to know that the effects of hypoxia at altitude are measured in seconds, not even minutes.

I wonder if you have ever put on an O2 mask in response to a hunch, some symptoms or due to a false warning light... only to remove it afterwards.

Better be safe than wrong, so to speak given the very short period of impending loss of consciousness.

Taking the numbers from wikipedia:
F430 - 9 to 15 secs
F400 - 15 to 20 secs
F350 - 30 to 60 secs
F300 - 60 secs to 3 minutes
F250 - 3 to 6 minutes

Pilots will use the masks for other than pressure problems. For instance any indication of smoke will also have us put them on, as you can be incapacitated just as well by fumes as by lack of air.

Never from a hunch. QF30 was the only time I've even needed the mask in an airliner. Conversely I once had a failure of the oxygen system in an A4G, in which it delivered unregulated oxygen to the mask...at about 100 psi. In that case I ripped the mask off (we wore them at all times, unlike Tom Cruise)...and was then given the problem that my cabin was at about 20,000 feet (it was pressurised to half the outside level). So the response to that was to roll inverted and pull through.

 

[Skyhigh777]

I think it's a combination of the way it isn't reactive, and also because it tends to leak out more slowly.

I'm not sure if this is part of the reasoning for using nitrogen in airplane tires, but i know that nitrogen doesn't expand as much as air does when heated. I guess if the tires heat up, it would keep the pressure more consistent.

 

[marki]

Ask The Pilot

The gas is inert and non flammable and causes the bends in humans because it does not dissolve as well in liquids. With change in pressure it will fizz much like opening a CocaCola bottle.(bends)
78% Nitrogen is in the air we breath. In its liquid form we use it in medicine for cryotherapy and preserving tissues and making flowers shatter or ice-cream really quickly !

 

[mjt57]

JB, given that the northern hemisphere is in the grip of a rather cold winter, I'm wondering how well the engines perform in low temps compared to summer days.

When we ran a gas turbine power station the engines (based on the PW ones of 707 and 737 fame) could vary in up to 40 percent output. Eg. whilst rated for 50MW, on cold winter days they'd easily romp in at 60MW+ but on days like we're experiencing this week they'd be lucky to hit 30MW max output.

Presumably, if you're doing LHR runs in the coming days or weeks, that you'd see a difference between taking off from DXB and from LHR.

Also, does the colder air affect lift much?

 

[Skyhigh777]

JB, given that the northern hemisphere is in the grip of a rather cold winter, I'm wondering how well the engines perform in low temps compared to summer days.

When we ran a gas turbine power station the engines (based on the PW ones of 707 and 737 fame) could vary in up to 40 percent output. Eg. whilst rated for 50MW, on cold winter days they'd easily romp in at 60MW+ but on days like we're experiencing this week they'd be lucky to hit 30MW max output.

Presumably, if you're doing LHR runs in the coming days or weeks, that you'd see a difference between taking off from DXB and from LHR.

Also, does the colder air affect lift much?

I was wondering this myself.

I'm currently staying near Toronto Canada, it was pretty close to -50 Celsius last week. It seemed a lot or local flights were canceled, but the long haul flights were mostly a go (Emerates A380, DXB-YYZ for instance flew in and out during an ice storm) What is it about the cold weather that would cancel a flight? is it mostly to do with runway conditions, or is there an actual danger to the plane while cruising?

Thanks

 

[jb747]

JB, given that the northern hemisphere is in the grip of a rather cold winter, I'm wondering how well the engines perform in low temps compared to summer days.

When we ran a gas turbine power station the engines (based on the PW ones of 707 and 737 fame) could vary in up to 40 percent output. Eg. whilst rated for 50MW, on cold winter days they'd easily romp in at 60MW+ but on days like we're experiencing this week they'd be lucky to hit 30MW max output.

Presumably, if you're doing LHR runs in the coming days or weeks, that you'd see a difference between taking off from DXB and from LHR.

The engines are flat rated to about 60ºC, which basically means we can achieve the full 72,500 lbs up to that temperature. The FADECs will limit them to that thrust level at lower temperatures.

Also, does the colder air affect lift much?

This should answer all of your questions Density altitude - Wikipedia, the free encyclopedia

The easiest way to think of it is that the earth sucks on hot days.....

 

[jb747]

I was wondering this myself. I'm currently staying near Toronto Canada, it was pretty close to -50 Celsius last week. It seemed a lot or local flights were canceled, but the long haul flights were mostly a go (Emerates A380, DXB-YYZ for instance flew in and out during an ice storm) What is it about the cold weather that would cancel a flight? is it mostly to do with runway conditions, or is there an actual danger to the plane while cruising?

You obviously need the runways and taxiways to be cleared. The aircraft has to be deiced. Basically ZERO ice or snow is allowed on the upper surfaces.

Toronto is pretty well prepared as far as deicing gear is concerned. Even so, operations slow to a complete crawl in those conditions, and many flights would have been cancelled simply because there would no longer have been sufficient airport capacity for them to go ahead.

Perhaps the Emirates 380 was still hot from sitting in the desert sun.....

 

[legroom]

You obviously need the runways and taxiways to be cleared. The aircraft has to be deiced. Basically ZERO ice or snow is allowed on the upper surfaces.

Toronto is pretty well prepared as far as deicing gear is concerned. ...

Hi JB,

Can I then infer that some airports are not that well equipped as far as de-icing is concerned ?

Which one in Western Europe could you name as "well prepared" or you are not in a position to do so on a public forum ?

If so, could I send you a PM instead ?

Many thanks

 

[moa999]

legroom,

Any airport where ice is not a regular occurrence will have issues with it when it occurs.
It is just too costly too invest in equipment that might be used a few days every few years (particularly in the days of corporate owned airports).

Heathrow has had numerous issues when ice has been present.

 

[Jordy992]

Hi There,

2 questions.


Do you ever fly Ga aircraft in your spare time? say out of Bankstown or morrabbin?
secondly does the captain always taxi the aircraft?