Fuel — Time and Quantity
Correct fuel planning is not only safety-critical but also legally binding. The reference for non-commercial VFR in EASA states: NCO.OP.125 Fuel and oil supply — aeroplanes.
Consumption terms
| Term | Definition |
|---|---|
| Fuel burn / fuel flow | instantaneous consumption (l/h or gal/h, per POH) |
| Trip fuel | required for the planned leg (flight time × cruise consumption) |
| Taxi fuel | for taxi before take-off and after landing |
| Contingency fuel | unforeseen extra burn (e.g. non-standard wind, long approach) |
| Alternate fuel | leg to alternate aerodrome, if planned |
| Final reserve fuel | legal minimum at destination — day VFR: 30 min holding at 1500 ft AGL; night VFR: 45 min |
| Extra fuel | PIC discretion, per assessment |
EASA Part-NCO minimum requirement (NCO.OP.125)
Day VFR (NCO.OP.125 (b)(1)):
Trip fuel + 30 minutes holding reserve at 1500 ft above aerodrome under standard conditions.
Night VFR (NCO.OP.125 (b)(2)):
Trip fuel + 45 minutes holding reserve at 1500 ft above aerodrome under standard conditions.
Plus: contingency and alternate fuel if applicable (alternate optional for VFR).
Source: EASA Easy Access Rules for Part-NCO, NCO.OP.125 (status 2024).
Calculation example
Cessna 172, cruise consumption 9 USG/h. Plan: 2
h flight, day, VFR.- Trip fuel: 2.0 h × 9 USG = 18 USG
- Taxi/start: about 0.5 USG
- Contingency (5 % of trip): 0.9 USG → round up to 1 USG
- Final reserve (30 min × 9 USG/h): 4.5 USG
- Total fuel on board (FOB) required: 18 + 0.5 + 1 + 4.5 = 24 USG
C172 standard tank: 53 USG, of which ~50 USG usable (POH). → Ample reserve; partial fill may suffice (mass & balance!).
Practical rules of thumb
- Always include the reserve — no "it'll be fine" margins.
- Re-check with current wind/TAF — headwind extends flight time.
- In-flight fuel check every 30 min — read tank gauges, compare with plan.
- Tank switching per POH — for twin or tank-switching procedures, strictly follow.
What to do with low fuel?
- Immediately reduce consumption: choose best L/D speed (POH), optimise altitude.
- Head for the nearest suitable airport — not necessarily destination.
- Inform traffic: declare "minimum fuel" — NO priority, but advisory to ATC.
- If necessary "Mayday Mayday Mayday Fuel" — priority over everything.
Fuel pre-flight check
- Water drain sample: from each tank drain — check for water/sediment.
- Correct fuel grade (avgas 100LL for most piston engines; Jet A-1 for turbines).
- Functioning fuel gauges — verify before each flight (POH).
- Visual check of quantity (stick or sight gauge) rather than relying on gauge alone.