% of fuel used in take of and landing

Jesper

What percentage of fuel is used in take off and landing of a flight on a standard to short flight. I've heard somewhere that its 90%?? Is this possible? I've also got to win a bet!

WeeDiddly

Not necessarily. It depends on the lenth of the flight and weather conditions etc.(to a certain extent)
There is no way take-off and landing alone would use 90%
Take a typical flight from Knock Airport to Heathrow(My figures are approx. because you haven't specified the type of plane)
The airline, will say that because the route isn't a very popular one, we will only need to fill the aircraft to about 70% capacity because thats all we need and also for safety reasons.
Then, during take-off the turbolence may add a certain amount of consumption.... just like the wind pushing against you on a bike...so lets take it that it uses 35% of the fuel at take-off... and after it reaches an altitude of whatever, the engines will constantly be running therefore constantly using fuel. When it lands, it uses very little fuel because the engines aren't needed. it should have abvout 10-15% fuel left over by the time it lands.

My cousin is the guy who programmed the system for British Airways which calculates how much fuel is required for each flight/route by comparing the number of passengers/weather conditions to the amount of fuel required. This is necessary because it must not have too much fuel when landing in case there is a crash landing... (regulations in england)

Jesper

thanks. I'm still not convinced though. anyone want to put percentages to this would be great.

shanew

there are some formula at this link if you're interested ....

http://www.b737.org.uk/rulesofthumb.htm

using a B737 as an example it looks like approx 30kgs/hour - and this
is reduced during the landing phase.

I would image that besides the actual take-off run the climb to altitude
(which would need some power) would last much longer than take-off
and therefore use more fuel.

there is also a B737 fuel planner at -

http://www.metacraft.com/737NGFP/

I have not used this - maybe be this will be able to give you
some figures ...

Shane

jmayo

Fuel used on landing much less than fuel used on takeoff.
From GA perspective an aircraft would have listed fuel ammount necessary to climb to say 2000 ft at best climb speed. Now this amount can be affected by weather (winds, temperature, altitiude of airfield), the weight of pasengers/freight and fuel on board.

Does your 90% include fuel used to get to cruising altitude?
Think about it, if 90% of fuel used on takeoff you would not get very far

WexCan

Also remember for commercial flights, a certain amount of contingency fuel is required in case you need to hold/divert. This figure is usually over 10% so that would leave no fuel for the cruise if 90% was accurate.

astrofool

Either way, it shows how environmentally unfriendly the Shannon stopover is/was (big jets taking off twice).

jmayo

astrofool wrote: »

Either way, it shows how environmentally unfriendly the Shannon stopover is/was (big jets taking off twice).

Haven't heard that used before as reason to axe it

Every flight be it commerical or pleasure has to have reserve fuel on board.
Flying a single engine small aircraft may not mean you are in hold in the traffic pattern of Heathrow, but it could mean having to divert to another airfield due to weather.
You also have to factor in taxi fuel as well as take off fuel, fuel for the climb, cruise and landing and the reserve.

Maybe the 90% referred to the space shuttle ?

highlydebased

WeeDiddly wrote: »

Not necessarily. It depends on the lenth of the flight and weather conditions etc.(to a certain extent)
There is no way take-off and landing alone would use 90%
Take a typical flight from Knock Airport to Heathrow(My figures are approx. because you haven't specified the type of plane)
The airline, will say that because the route isn't a very popular one, we will only need to fill the aircraft to about 70% capacity because thats all we need and also for safety reasons.
Then, during take-off the turbolence may add a certain amount of consumption.... just like the wind pushing against you on a bike...so lets take it that it uses 35% of the fuel at take-off... and after it reaches an altitude of whatever, the engines will constantly be running therefore constantly using fuel. When it lands, it uses very little fuel because the engines aren't needed. it should have abvout 10-15% fuel left over by the time it lands.

My cousin is the guy who programmed the system for British Airways which calculates how much fuel is required for each flight/route by comparing the number of passengers/weather conditions to the amount of fuel required. This is necessary because it must not have too much fuel when landing in case there is a crash landing... (regulations in england)

There are no NOC-LHR flights at all.

Would want to be a very uneconomical aircraft to use 35% of its fuel at takeoff!!! Would not even use 1%.

In busy airports, the have "taxi fuel"......fuel they burn off during the taxi. In the likes of LHR and JFK, this is quite high.

FlutterinBantam

All airlines use standard taxi fuel figures for calculating fuel consumption.

Typically for a B747 this would be 500k - half a tonne.

B737 apx 150 kgs and so on.

Average fuel burn off (trip fuel) for an a330 Dub-JFK would be around 37000kgs.

Depending on operational conditions, at the destination, the fuel at take off would be around 41/42k .

The take off phase of the flight of course will use the most fuel,but nowhere near 90%.

Price of fuel would also be a factor in planning short haul fuel loads.
It would make sense to take on the minimum in dear airports and tanker up in airports where fuel is cheap.

WeeDiddly

Neon-Circles wrote: »

There are no NOC-LHR flights at all.

Would want to be a very uneconomical aircraft to use 35% of its fuel at takeoff!!! Would not even use 1%.

Yep, I know. I live in Westport. If we should be so lucky! Maybe Stanstead/Gatwick might be a much better example, but anyway...thanks for pointing that out

As regards the 35%, I was speaking that 35% would be 35% of the total amount of fuel, but Knock to Gatwick/Stanstead would be considered a short flight anyway therefore less fuel capacity is required, and take-off would take a pretty large chunk of fuel, to climb to correct altitude.

Nev.

Jesper

Some good point thanks. But to clarify if a plane is going to use 100 tonne of fuel over its full journey (i.e. no reserves etc.) would 60 tonne be used gaining the correct alltitude then maybe 15 for the journey then 35 for decent park up etc.
I'm clutching at straws here but would love to win this argument.

Foggy43

A 747-400 LHR to JFK will depart with 90,000kgs of fuel. Chocks to chocks is roughly 7 hours. The engines will burn 2.5 tonnes per hour each, a total of 10 tonnes per hour. At shut down there will be 15,000 kgs remaining.

The figures are approximate. Weather, freight and holding conditions. Aprox 60 tonnes of the 75 will be burnt in cruise. So 80% approx used in cruise. Engines only run at full power for 5 to 10 minutes.

Say the same aircraft had to return to LHR shortly after takeoff due to an emergency. It would have to dump fuel. This is prevent stress on the landing gear and wings. On take off, lift is taking away the stress from the wing mounting bolts. On a landing the you have lift generated under the wing forcing it down along with the weight of the fuel. The aircraft manafacturer will give guidelines on safe landing weights.

Tenger

Deleted at Tengers request by Mod

FlutterinBantam

Sorry Bramble , but those figs are totally off the mark.

The trip fuel for an a320 Dub-Lhr would be apx 1900 to 2100kgs

What the consumption breakdown for the take off/cruise/approach and landing phases are exactly I cannot say.

So if it takes off with 7000 kgs it will land in Lhr with apx 5000kgs.

rest of your points are accurate enough.

Tenger

Deleted at Tengers request by Mod

FlutterinBantam

Good man. The loadsheet will only tell you the trip fuel/take off fuel, and the various rtow limitations associated with those figures.The RTOW of a Dub-Lhr will nearly always be limited by the landing wt maximum.

You'll get the T/o weight/landing wt. and empty tank weight plus a few other things.

For fuel consumption you need to get a flight plan to have any idea.