Flying Hours Calculator

Aircraft Endurance Calculator

function calculateFlyingHours() { var totalFuelCapacity = parseFloat(document.getElementById('totalFuelCapacity').value); var fuelConsumptionRate = parseFloat(document.getElementById('fuelConsumptionRate').value); var requiredFuelReserve = parseFloat(document.getElementById('requiredFuelReserve').value); if (isNaN(totalFuelCapacity) || isNaN(fuelConsumptionRate) || isNaN(requiredFuelReserve) || totalFuelCapacity < 0 || fuelConsumptionRate <= 0 || requiredFuelReserve = totalFuelCapacity) { document.getElementById('usableFuelResult').textContent = 'Not enough fuel'; document.getElementById('fuelForReserveResult').textContent = fuelForReserve.toFixed(2); document.getElementById('flyingHoursResult').textContent = '0.00'; return; } var usableFuel = totalFuelCapacity – fuelForReserve; var flyingHours = usableFuel / fuelConsumptionRate; document.getElementById('usableFuelResult').textContent = usableFuel.toFixed(2); document.getElementById('fuelForReserveResult').textContent = fuelForReserve.toFixed(2); document.getElementById('flyingHoursResult').textContent = flyingHours.toFixed(2); }

Understanding Aircraft Endurance and Flying Hours

For pilots and flight planners, calculating an aircraft's endurance – the maximum time it can remain airborne – is a critical aspect of flight safety and operational efficiency. This Aircraft Endurance Calculator helps you determine the maximum flying hours based on your aircraft's fuel capacity, fuel consumption rate, and required fuel reserves.

What is Aircraft Endurance?

Aircraft endurance refers to the total time an aircraft can stay in the air under specific conditions, primarily limited by its fuel supply. It's distinct from range, which measures the maximum distance an aircraft can travel. Endurance is crucial for missions requiring loitering, search and rescue operations, or simply ensuring a safe arrival at the destination with adequate reserves.

Key Factors in Calculating Flying Hours

Several factors influence an aircraft's endurance. Our calculator focuses on the primary determinants:

1. Total Fuel Capacity: This is the maximum amount of fuel your aircraft's tanks can hold, typically measured in gallons or liters. It's the starting point for any endurance calculation.
2. Fuel Consumption Rate: Also known as fuel burn, this is the rate at which your engine consumes fuel, usually expressed in gallons per hour (GPH) or liters per hour (LPH). This rate can vary significantly based on engine type, power setting, altitude, and aircraft weight. For planning purposes, pilots often use an average or cruise consumption rate.
3. Required Fuel Reserve: Aviation regulations (e.g., FAA, EASA) mandate that aircraft must land with a certain amount of reserve fuel. This reserve is a safety buffer to account for unforeseen delays, holding patterns, diversions, or unexpected headwinds. For Visual Flight Rules (VFR) day operations, a common reserve is 30 minutes of flight at normal cruise speed, while VFR night and Instrument Flight Rules (IFR) often require 45 minutes or more, sometimes including fuel to an alternate airport. This calculator uses minutes for simplicity.

How the Calculator Works

The calculator uses a straightforward process to determine your aircraft's maximum flying hours:

1. Calculate Fuel for Reserve: It first determines how much fuel is needed to meet your specified reserve time by multiplying your fuel consumption rate by the reserve time (converted to hours).
2. Determine Usable Fuel: This is the total fuel capacity minus the fuel required for the reserve. This is the actual amount of fuel available for your flight.
3. Calculate Maximum Flying Hours: Finally, the usable fuel is divided by the fuel consumption rate to give you the maximum time the aircraft can fly before dipping into its reserve.

Example Calculation

Let's consider a common general aviation aircraft:

• Total Fuel Capacity: 50 Gallons
• Fuel Consumption Rate: 8.5 Gallons/Hour (typical for a Cessna 172 at cruise)
• Required Fuel Reserve: 45 Minutes (0.75 hours)

Using the calculator:

1. Fuel for Reserve: 8.5 GPH * 0.75 hours = 6.38 Gallons
2. Usable Fuel: 50 Gallons – 6.38 Gallons = 43.62 Gallons
3. Maximum Flying Hours: 43.62 Gallons / 8.5 GPH = 5.13 Hours

This means the aircraft can fly for approximately 5 hours and 8 minutes before reaching its mandatory fuel reserve.

Important Considerations

• Actual vs. Planned: Always remember that actual fuel consumption can vary. Factors like wind, altitude changes, power settings, and even aircraft weight can affect your true fuel burn. Always add a personal safety margin.
• Pre-flight Planning: This calculator is a tool for pre-flight planning. Always cross-reference with your aircraft's Pilot's Operating Handbook (POH) for precise fuel consumption figures and reserve requirements.
• Units: Ensure consistency in units. If your fuel capacity is in liters, your consumption rate should also be in liters per hour. This calculator uses gallons.

By accurately calculating your aircraft's endurance, you can make informed decisions, plan safer flights, and avoid unexpected fuel emergencies.