Choose your plane carefully in winter.

chillidoggy

This kind of makes me wonder just how much reserve fuel the things have. I was led to believe that they use more fuel taking off and reaching cruising altitude than the entire rest of the flight. I also imagine that once at altitude, they're constantly throttling back as the fuel burns off, but I'm not sure about that one. Where's the resident Bruce Dickenson wannabee, Emp when you need him?

http://mashable.com/2015/01/09/boeing-757-flight-diversions/

Gassage

chillidoggy said:

This kind of makes me wonder just how much reserve fuel the things have. I was led to believe that they use more fuel taking off and reaching cruising altitude than the entire rest of the flight. I also imagine that once at altitude, they're constantly throttling back as the fuel burns off, but I'm not sure about that one. Where's the resident Bruce Dickenson wannabee, Emp when you need him?

It normally depends on routing. However, 1.25 hrs is pretty mandatory. Re throttling back, they'll cruise. They also have a little in th schedule normally and throttling back is as much to save engine wear as fuel.

chillidoggy

Re the throttling back, what I'm banging on about there, is presumably as the plane gets lighter and lighter as its fuel burns off, then less and less power is required to keep it flying at the same speed? I'm talking very small throttling back adjustments, obviously made by a flight computer of some kind. Or do they simply not bother, and it gets faster and faster?

Gassage

I would suggest that AP will deal with that. And, I'd also assume (to be corrected) that the flight plan would be pre filed.

Don't forget the fuel and power effects of head and tail winds - pilots crave the jet stream behind the plane!

randomhandclaps

The airlines have carried out careful economic research and it has repeatedly shown that a crashed plane burns the least fuel and evokes virtually zero refund claims for the obvious delay.

mike_l

Aviation law (IIRC) says you must have enough fuel to reach you airfield, and your diversion airfield, if you cannot land at your primary.

Elwood

The volume of extra fuel is ultimately decided by the Captain/FO when on the aircraft based on know weather, expected delays for take off and landing. The further the distance and the large the distance between airports the more reserve fuel is carried.

As I understand it they are required to have enough in reserve for two attempted landings at their destination, divert to the nearest airdrome and two more landing/take off runs. Shorthaul it's calculated to be quite close as fuel is one of the biggest business costs. Though now fuel prices will have dropped and that will shortly translate into cheaper ticket prices.

Which airlines/aircraft types do you consider less safe in the winter?

chillidoggy

Apologies to everyone, the link didn't appear the first time around, and all will become clear now. Hopefully.

Emp_Fab

chillidoggy said:

Where's the resident Bruce Dickenson wannabee, Emp when you need him?

I'm free ! (/John Inman).

Sorry.... what was the question ?  Yeah, they'll use less fuel per hour as the overall weight drops during flight, but the flight computer deals with all that.  They don't speed up, they throttle back.  As for the article.... I'm not even sure what point they were trying to make !  It's irrelevant really - each airline has it's own fuel policy, but as has been pointed out, it's usually enough for the journey, plus enough to reach at least one alternate airport and a degree of hold time.  In Ryanair's case, it's enough to get you to the airport that isn't where you thought it was and half a gallon more. ;-)

Any captain who loads insufficient fuel to meet all of those requirements is heading for the dole queue.... or.... the rapidly approaching ground along with all his/her passengers !

The only thing I would factor in in picking an aircraft type for a long flight over water would be (after comfort !) the number of engines.  Whilst multiple engine failures are incredibly rare, I'd rather be on a four engined plane than a twin.

mike_l

It's only relatively recently (inside the last 20 years) that 2-engined aircraft have been permitted for passengers over the Atlantic.

Before it was 4.

ICBM

Because of improving engine reliability.

Single engine failures on four-engine planes are actually more likely, simply because there are twice the number of engines so twice the chance of *a* failure. Although as far as I know any four-engine plane can fly on two, so they are still safer overall since they can still fly after two failures, whereas a two-engined one can only glide...

As far as I know, the only two-engine failure over water so far in a two-engine plane was the one that had to glide to the Azores, and did land safely - and that was due to a fuel leak followed by misdiagnosis and crew error, in pumping fuel from the good side to the leaking side, not engine failure.

If the type of aircraft seems to make a difference as to whether a fuel divert is necessary or not applies it may be down to airline policy rather than the plane, since it's perfectly possible to operate larger aircraft without full fuel load - in fact normal, since it's more efficient.

Sambostar

mike_l said:

It's only relatively recently (inside the last 20 years) that 2-engined aircraft have been permitted for passengers over the Atlantic.

Before it was 4.

This.  Cheaper to half fill two twin engine planes than a quarter full 4 engine.

I wouldn't be flying to the East coast at the moment, likely to run out of fuel with that headwind.

http://www.dailymail.co.uk/travel/travel_news/article-2903168/British-Airways-flight-hits-powerhouse-jet-stream-New-York-London-reaching-near-supersonic-speeds-745mph.html

I thought they generally have around 800km of spare fuel, but that is eliminated completely with headwinds of 77mph. 80mph as an average and you won't make the Heathrow Chicago direct flight and will have to divert.

chillidoggy

It was speed over ground, not speed through the air. So the supersonic claim is a bit misleading. But they still got home a damned sight faster!

Emp_Fab

All this stuff about running out of fuel due to headwinds is utter bollocks !  They know the winds and the forecasts before they even calculate the fuel requirements, let alone take off !  They factor this stuff in.  It's not rocket science.

chillidoggy

Steady on old chap, who said anything about running out of fuel? It's the possibility of getting diverted to refuel during winter headwinds that the article's about, thereby adding a shedload of inconvenience to an already tedious long-haul flight. Actually, I bet the refuellers are coining it.

Emp_Fab

Same argument.  Why would you need to refuel if you've worked out correctly what you need in the first place ?

ICBM

Emp_Fab said:

Same argument.  Why would you need to refuel if you've worked out correctly what you need in the first place ?

Exactly. It will be an airline policy of carrying minimum fuel, or using an aircraft type whose maximum range even fully fuelled is just a bit too short to cope with a small change in conditions (which is what I think the article is about). ie cost-cutting, rather than aircraft safety.

Pilots don't want to die any more than the rest of us and don't want to lose their jobs either, you can be quite sure they wouldn't even take off if they didn't think they were going to make it to the destination with not only enough fuel to get there but the minimum safety reserve as well.

VimFuego

I pity the poor sod who's got to go outside mid-flight with a jerry can and top up the tank.

chillidoggy

Emp_Fab said:

Same argument.  Why would you need to refuel if you've worked out correctly what you need in the first place ?

 The article is about planes which would ordinarily have enough fuel to complete their journey but have to divert and refuel due to adverse headwinds. So they might have worked it out correctly in the first place, but the unexpected headwinds balls-up their calcs. You are therefore more likely to be diverted and refuel if you ride long-haul in a 757 in winter across the pond.

hugbot

Re planes and fuel

Axe_meister

They just ran out of G&Ts in first class.