Alternate requirements (is an alternate required, and if so, how much fuel is required?)
Type of fuel at destination and alternate (what fuel is provided, and is it self or full-serve?)
Fuel availability (are the pumps working?)
Aircraft weight limits relative to required performance (is a lighter weight required to takeoff?)
VFR Fuel Requirements:
No person may begin a flight in an airplane under VFR conditions unless (considering wind and forecast weather conditions) there is enough fuel to fly to the first point of intended landing and, assuming normal cruising speed:
During the day, fly after that for at least 30 minutes; or
At night, fly after that for at least 45 minutes
No person may begin a flight in a rotorcraft under VFR conditions unless (considering wind and forecast weather conditions) there is enough fuel to fly to the first point of intended landing and, assuming normal cruising speed, to fly after that for at least 20 minutes
IFR Fuel Requirements:
No person may operate a civil aircraft in IFR conditions unless it carries enough fuel (considering weather reports and forecasts and weather conditions) to:
Complete the flight to the first airport of intended landing;
Fly from that airport to the alternate airport; and
Fly after that for 45-minutes at normal cruising speed or, for helicopters, fly after that for 30-minutes at normal cruising speed
Although the 45-minute rule above will never change, pilots may omit the requirement to carry enough fuel to fly from an alternate airport if:
A standard instrument approach procedure to, or a special instrument approach procedure exists at the first airport of intended landing; and
Appropriate weather reports or weather forecasts, or a combination of them, indicate the following:
Aircraft Other Than Helicopters:
For at least 1 hour before and for 1 hour after the estimated time of arrival, the ceiling will be at least 2,000 feet above the airport elevation, and the visibility will be at least 3 statute miles
Helicopters:
At the estimated time of arrival and for 1 hour after the estimated time of arrival, the ceiling will be at least 1,000 feet above the airport elevation, or at least 400 feet above the lowest applicable approach minima, whichever is higher, and the visibility will be at least 2 statute miles
Pilots must plan for enough fuel to fly to the point of intended landing, considering wind and weather, and 30 minutes (day), or 45 minutes (night) after that
No alternate airport is required
Governed by FAR 91.151
Instrument Flight Rules:
Pilots are required to plan for fuel to a destination, to an alternate, and after that for 45 minutes at normal cruising speed or, for helicopters, fly after that for 30 minutes at normal cruising speed
Governed by FAR 91.167
Fuel Planning for Alternate Airports:
Visual Flight Rules:
There are no requirements within the Federal Aviation Regulations to select and plan for an alternate
This does not preclude you from being prepared
Instrument Flight Rules:
FAR 91.169 can generally be summed up using the 1-2-3 rule:
If the weather is forecast between 1 hour before to 1 hour after ETA to be below 2000' ceiling or less than 3 miles visibility, an alternate is required
In addition to the 1-2-3 rule, if your destination does not have an instrument approach procedure published, an alternate must be chosen in case the field was to fall into instrument meteorologic conditions
If an alternate is required, the alternate airport must have an instrument approach while meeting certain criteria:
800' ceiling, 2 miles visibility, if non-precision approach
600' ceiling, 2 miles visibility, if precision approach
If no approach exists for the alternate runway, descent from cruising altitude must be possible under Visual Flight Rules
Note that minimums published for approaches may differ
Fuel Planning Tips:
Be present every time during aircraft fueling. Verify fuel grade, quantity, and tanks to be filled
Check for water or contaminants
Secure fuel caps after you check the tank and double-check them before the engine start
Determine available fuel in hours and minutes instead of gallons and pounds, and plan to land with at least an hour of usable fuel
Lean the mixture to achieve the best performance, range, and endurance
Recalculate range and endurance hourly to maintain adequate reserves
Understand how and when to use boost pumps, auxiliary tanks, fuel transfer pumps, and switch tanks before reaching pattern altitude
Use a timer to remind you to switch tanks during flight
Despite VFR pilots being exempt, plan for an alternate in case of unplanned weather, airport closure, or if fuel becomes unavailable