How much spare fuel does a typical aircraft have?

For anyone who cares... They ended up being diverted to a mix of Cardiff, Bristol, Exeter and Birmingham. All very late, so obviously carrying plenty of extra fuel in line with the suggestions above
 
Fuel planning rules are a bit long winded but broadly speaking the minimum fuel you should have when you arrive at your destination airfield is enough to fly to an alternate destination (if you were to find your planned airport closed, for example) plus 30 minutes holding fuel (final reserve).

This would be the absolute legal minimum and if you found yourself in a situation where you where going to start burning your final reserve fuel you would have to declare a mayday to air traffic control which causes a big fuss.

In reality, flight crews will usually carry extra fuel on top of the minimum required calculated by the flight planning software. This amount would depend on things like the weather at your destination on the day. Thunderstorms, for example, would mean I would probably plan another 30-40 mins of fuel on top of the legal minimum. As a general rule I usually stick another 10 mins of fuel on top of whatever is calculated just in case, altough airlines tend to frown upon this.

In addition, the flight planning software tends to be a bit conservative and calculates for a bit extra anyway so you generally arrive at your destination airport with more fuel than the software predicts.
 
Interestingly just read this part in the navigation book, I'm studying for a helicopter PPL, so the book says for a private pilot the total fuel is the sum of;
Taxi fuel
Trip fuel (including climb/descent during cruise + arrival procedures at destination)
Contingency fuel (5% of trip fuel or 3% of trip fuel if en route alternate is available or 20mins flying based on fuel consumption history for that a/c - whichever is higher)
Alternate fuel (for a missed approach + landing, if 2 alternates, plan for the furthest)
Final reserve fuel (single engine piston 45min, helicopters 20min)
Minimum additional fuel (for 15mins of holding)
Extra fuel (commanders discretion)
Due for my first cross country soon so will have to start planning all this, solo cross country shortly after that which will be squeaky bum time!
 
Contingency fuel (5% of trip fuel or 3% of trip fuel if en route alternate is available or 20mins flying based on fuel consumption history for that a/c - whichever is higher)

I might be wrong, but I think this should be 5% or 3% ERA or 5 mins whichever is higher. (20 mins seems a lot for contingency fuel, which is essentially for things like the winds aloft being different to the forecast, or flying at a slight different altitude to which planned)

Also:

Final reserve fuel (single engine piston 45min, helicopters 20min)
Minimum additional fuel (for 15mins of holding)

Its been a long time since I flew light aircraft so I honestly can't remember, but this is lumped into a single 30 mins final reserve figure for category C and D transport aircraft.
 
Only large aircraft can dump fuel, typically B777, B747, A380 etc. Medium range aircraft like the B737 or A320, probably the most common short haul aircraft types have no capability to dump fuel. Plus its highly frowned upon.
 
Psycho Sonny said:
how so? they can dump the fuel if need be
Click to expand...

I'm no pilot and am willing to stand corrected. However 'full tanks' (which is what started the sub-discussion) wouldn't be routinely dumped before landing for several fairly obvious financial, environmental and other reasons. Just because a craft isn't already in a mayday situation on approach - and thus has foreknowledge to dump its fuel - doesn't mean a landing can't go wrong before the plane hits the tarmac, or as it hits the tarmac, or whatever. A full tank of aviation fuel isn't something I imagine one wants routinely sloshing/spraying/combusting during any such accident.
 
esmozz said:
Contingency fuel (5% of trip fuel or 3% of trip fuel if en route alternate is available or 20mins flying based on fuel consumption history for that a/c - whichever is higher)

I might be wrong, but I think this should be 5% or 3% ERA or 5 mins whichever is higher. (20 mins seems a lot for contingency fuel, which is essentially for things like the winds aloft being different to the forecast, or flying at a slight different altitude to which planned)

Also:

Final reserve fuel (single engine piston 45min, helicopters 20min)
Minimum additional fuel (for 15mins of holding)

Its been a long time since I flew light aircraft so I honestly can't remember, but this is lumped into a single 30 mins final reserve figure for category C and D transport aircraft.
Click to expand...

You may well be correct as the book is riddled with errors, but that's what is printed in it!
 
From EASA Part-CAT 150b

Contingency fuel, except as provided for in (b), which should be the higher of:
(i) Either:
(A) 5 % of the planned trip fuel or, in the event of in-flight replanning, 5 % of
the trip fuel for the remainder of the flight;
(B) not less than 3 % of the planned trip fuel or, in the event of in-flight
replanning, 3 % of the trip fuel for the remainder of the flight, provided that
an en-route alternate (ERA) aerodrome is available;
(C) an amount of fuel sufficient for 20 minutes flying time based upon the
planned trip fuel consumption, provided that the operator has established a
fuel consumption monitoring programme for individual aeroplanes and
uses valid data determined by means of such a programme for fuel
calculation; or
(D) an amount of fuel based on a statistical method that ensures an
appropriate statistical coverage of the deviation from the planned to the
actual trip fuel. This method is used to monitor the fuel consumption on
each city pair/aeroplane combination and the operator uses this data for a
statistical analysis to calculate contingency fuel for that city pair/aeroplane
combination;
(ii) or an amount to fly for 5 minutes at holding speed at 1 500 ft (450 m), above the
destination aerodrome in standard conditions.
Click to expand...
 
(C) an amount of fuel sufficient for 20 minutes flying time based upon the
planned trip fuel consumption, provided that the operator has established a
fuel consumption monitoring programme for individual aeroplanes and
uses valid data determined by means of such a programme for fuel
calculation

I stand corrected, although to be fair, I don't think I've ever seen this definition used in practise.

Edited to add: A B737 burns approximately 40 kg/min so for 20 minutes thats 800kg extra of fuel. Airline planners must have some way round that particular definition because rarely have I seen that much contingency fuel.
 
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They're probably going to opt for ii) 5 min at holding speed at 1500ft!

There's a lot in the book that won't be used in practice, how often do you whip out the CRP to work something out? There's an app for that..
 
I fly the Boeing 777. If we get to an airport and we are going to land with less than 30 minutes of fuel we MUST declare an emergency. There will be a lot of paperwork. I have never got that low on fuel and never wish to!

On a normal flight we have enough fuel to divert to another airport plus about 20 minutes spare to hold as well as 30 minutes emergency fuel.

If there is bad weather, lots of traffic we are planned to take extra and if we want we can add extra fuel on top of that too.


With regards to dumping fuel, if it's a time critical problem, like we just lost an engine after take off, we would not dump fuel but land overweight, the aircraft should be fine but the brakes will most likely get hot. Either way, the plane is going into the hangar for a while after an engine just failed....

On a very long sector at maxiumm take off weight and full tanks we will have to dump 100 tonnes of fuel to land without being overweight, that would take about 60 minutes.
 
Aircraft have max landing weights. In reality they would be fine landing heavy in most scenarios.

As stated above, it would be reported in an engineering handover book or something like that and the aircraft would be subjected to an extra "heavy landing" check above any standard maintenance.

I was also under the impression that if any aircraft is controllable and in no immediate danger, it would be most likely to just burn up fuel in a circuit if landing weight was a concern, gear that wont or cant be locked out for example.
 
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