Comprehensive Study Guide
Fuel Consumption & Reserve Planning Study Guide
Master FAR Part 91.151 reserve rules, volumetric flow rates, mixture leaning, and unusable fuel exclusions.
Editorially reviewed by the AviCalculator team
1. Regulatory Framework & Reserve Rules
Fuel planning questions on FAA knowledge exams evaluate both statutory legal compliance and numerical endurance math.
- FAR Part 91.151 (VFR Day): Enough fuel to fly to destination threshold plus 30 minutes at normal cruising speed.
- FAR Part 91.151 (VFR Night): Enough fuel to fly to destination plus 45 minutes at normal cruising speed.
- FAR Part 91.167 (IFR Operations): Fly to destination, fly from destination to alternate airport (if required), plus 45 minutes at normal cruising speed thereafter.
2. Governing Mathematical Formula
Total Dispatch Fuel = [ BurnRate (GPH) × Total ETE in Hours ] + Statutory Reserve Fuel
3. Practical Calculation Walkthrough
Exam Scenario: ETE is 2 hr 20 min. Cruise burn rate is 10.2 GPH. VFR Day flight. Find minimum dispatch fuel load.
- Convert Minutes to Decimal Hours: 20 / 60 = 0.333 hr. Total ETE = 2.333 hr.
- Calculate En-Route Fuel: 2.333 hr × 10.2 GPH = 23.8 gallons.
- Calculate 30-Min Day Reserve: 0.5 hr × 10.2 GPH = 5.1 gallons.
- Sum Total Mandatory Fuel: 23.8 + 5.1 = 28.9 usable gallons.
4. Common Exam Mistakes
Never include Unusable Fuel in endurance math. Unusable fuel rests below tank pickup lines and cannot feed the engine safely during uncoordinated flight. Dispatch manifests rely strictly on certified usable fuel capacity.
Test Your Knowledge
You've reviewed the theory. Now apply it to real FAA/EASA checkride questions to verify your understanding.