Running out of fuel is one of the most avoidable ways to lose an aircraft, which is why the rules never let you carry only what the trip itself needs.
This is general educational information, not operational, legal, or regulatory advice. Rules differ by authority and change over time. Always verify against current official sources and follow your operator's approved procedures.
The principle, and the ICAO baseline
Fuel planning answers a simple question with a margin built in: enough fuel to fly the planned route, reach an alternate if you cannot land at the destination, and still have a reserve untouched on arrival. The international baseline is ICAO Annex 6, which requires that a flight not begin unless it carries enough fuel to complete it safely, taking account of the conditions and of alternates, and which frames the modern fuel-planning schemes. The detailed figures, though, are written by each authority, and they differ, so attribute every reserve time or percentage to its source.
The FAA rules
In the United States the reserves are stated as flat times, in 14 CFR Part 91 for general operations and Part 121 for airlines:
- VFR, aeroplanes (14 CFR 91.151): enough fuel to fly to the first point of intended landing and then, at normal cruising speed, for at least 30 minutes by day or 45 minutes by night.
- IFR (14 CFR 91.167): enough to fly to the first airport of intended landing, then, where an alternate is required, from that airport to the alternate, then for 45 minutes at normal cruising speed (with a different figure for helicopters). Note the singular: a Part 91 flight plans against one alternate, the one it has filed, not against the most distant of several.
- Domestic airline operations (14 CFR 121.639): enough to fly to the destination, then to the most distant required alternate, then for 45 minutes at normal cruising fuel consumption. The "most distant alternate" wording is a Part 121 feature; do not carry it back into 91.167.
The alternate leg in 91.167 is conditional, and the condition is the FAA's well-known 1-2-3 rule. Under 14 CFR 91.167(b) the alternate fuel is not required at all if the first airport of intended landing has a published standard instrument approach procedure and, for at least 1 hour before to 1 hour after the estimated time of arrival, the appropriate forecasts give a ceiling of at least 2,000 ft above airport elevation and visibility of at least 3 statute miles. Meet all of that and the requirement collapses to destination fuel plus the 45 minutes; miss any of it, including the published-approach limb, and you fly the alternate leg. The same 1-2-3 test decides whether you must file an alternate in the first place, which our guide to choosing an alternate aerodrome works through.
These are the FAA's figures; they are not EASA's and they are not universal.
EASA for general aviation: NCO.OP.125
If you fly a light aeroplane privately in Europe, the rule that binds you is Part-NCO, not the airline rules in the next section, and it is much closer to the FAA's than the "EASA has no reserve time" folklore suggests. NCO.OP.125 requires the commander to be satisfied, before departure, that the aeroplane carries enough fuel and oil to complete the flight safely, taking the conditions into account. The planning criteria that put numbers on that sit in AMC1 NCO.OP.125(b), and on top of the fuel to reach the destination (and an alternate, where one is required) they set a final reserve:
- 30 minutes at holding speed at 1,500 ft above the destination aerodrome, in standard conditions, for VFR by day;
- 45 minutes at holding speed at 1,500 ft, for VFR by night and for IFR;
- 10 minutes at maximum continuous cruise power at 1,500 ft for a local VFR flight by day that takes off and lands at the same aerodrome and always stays within sight of it. Note the different condition: this one is set at cruise power, not at holding speed.
So EASA does set a flat final reserve for general aviation, and the reader of this article is almost certainly the pilot it applies to. If you are planning a European VFR cross-country, 30 minutes by day and 45 minutes by night is the number, from AMC1 NCO.OP.125(b), and it happens to line up with the FAA's Part 91 figures without being the same rule.
The EASA fuel scheme for commercial air transport
The rules usually quoted as "the EASA fuel rules" are the commercial air transport ones, and they govern an airline, not a private light aeroplane. Here EASA does not lean on a single reserve time. Its Air Operations rules, restructured by Regulation (EU) 2021/1296 and now in CAT.OP.MPA.180 and CAT.OP.MPA.181, require the usable fuel (or energy) to be built from named components:
- Taxi fuel for ground movement before take-off;
- Trip fuel to fly from take-off to landing at the destination;
- Contingency fuel to cover unforeseen deviations from the plan;
- Destination-alternate fuel to reach the alternate where one is required. Where no alternate is required, this component does not fall to zero: the scheme still asks for enough to hold for 15 minutes at 1,500 ft above the destination aerodrome in standard conditions;
- Final reserve fuel, a protected minimum based on a holding time at the alternate (or destination) that you should not plan to use;
- Additional fuel, where the type of operation demands it;
- Extra fuel, to cover anticipated delays or specific operational constraints that can be predicted at planning;
- Discretionary fuel, where the commander requires it.
The last three are three separate components, which is worth keeping straight: "extra" is the planning-side allowance for delays and constraints you can foresee, while "discretionary" is the quantity carried at the sole discretion of the commander, and collapsing them into one line loses the distinction the regulation is drawing.
The exact percentages and times attach to these components in the regulation, and they are revised over time, so read the current EASA Air Operations rules for the figures rather than memorising a number. The structure is what makes the commercial EASA scheme different from the FAA's Part 121 rule. It is not evidence that EASA declines to set a reserve time, because for general aviation, as the section above shows, it plainly does.
Conceptually the components stack up into the fuel an airliner loads: taxi fuel for the ground movement, then trip fuel for the planned flight, then contingency fuel for the unexpected, then destination-alternate fuel to divert, then the final reserve that should still be there on arrival, with any additional, extra and discretionary fuel on top. Seen that way, the value of the scheme is plain: it forces every part of the journey, including the parts you hope not to fly, to be accounted for in its own right rather than buried inside a single round figure.
Why the margin is never optional
Reserves are minimums, not targets. The real fuel figure has to absorb headwinds stronger than forecast, a runway change that lengthens the taxi, holding for traffic or weather, a missed approach and diversion, and the simple fact that the unusable fuel in the tanks cannot be burned. A tank that is physically full is not the same as a flight that is legally and sensibly fuelled, because what matters is fuel against the planned route and its contingencies, not litres in the wings. When the plan is tight, the answer is more fuel or a shorter leg, not optimism.
Common pitfalls
- Treating the reserve as usable. Final reserve fuel exists to still be there on arrival, not to extend the flight.
- Assuming one number fits. The FAA's 30 and 45 minutes are Part 91 figures; EASA's Part-NCO final reserve is 30 minutes for VFR by day and 45 for VFR by night or IFR; the EASA commercial scheme is component-based; airline rules differ again. Attribute every figure.
- Reading the EASA airline scheme as the rule for your private flight. CAT.OP.MPA.180 and 181 govern commercial air transport. A private light aeroplane in Europe is flown under Part-NCO, which does set a flat final reserve.
- Carrying Part 121's "most distant alternate" into Part 91. 91.167 plans against the one alternate you file; the most-distant wording belongs to 121.639.
- Forgetting the second limb of the 1-2-3 rule. The alternate leg drops out under 91.167(b) only if the destination also has a published instrument approach, not on the weather alone.
- Assuming no alternate means no alternate fuel. Under the EASA commercial scheme, a flight with no required alternate still carries enough to hold for 15 minutes at 1,500 ft above the destination.
- Ignoring the conditions. Wind, weather, holding, and a possible diversion all push the required figure above the bare minimum.
- Forgetting unusable fuel and the figures change. Some fuel cannot be used, and the regulations are amended, so check the current rule for your operation.
In Pilot EFB
Pilot EFB does not calculate fuel or reserves, and it is not a certified Electronic Flight Bag. It is a study and planning aid that keeps your weather, NOTAMs, flight time, and logbook in one offline-first place, which helps you judge the conditions a fuel plan has to survive. Work the fuel itself from the approved aircraft data and your operator's fuel policy, and treat the regulation for your operation as the binding requirement. Saved data stays readable offline; pulling fresh data needs a connection.