What is alternate airport planning in aviation?

It is the process of selecting and preparing for a suitable airport to divert to if landing at the destination becomes impossible.

How do you choose an alternate airport?

Select an airport that meets regulatory requirements, is operationally available, and has suitable weather, facilities, and approach aids.

What are the EASA alternate airport rules?

EASA requires checking operational status, weather minima, navigation aid availability, and ensuring minimum fuel reserves for the alternate.

How is alternate fuel calculated?

By considering the distance to the alternate, expected winds, and landing mass, then referencing aircraft performance tables.

What is the minimum fuel on arrival at an alternate airport?

For turbine aircraft, at least 30 minutes at holding speed at 1500 ft above the alternate aerodrome elevation.

Alternate Airport Planning

Hard4 min readFlightplanning

Moderately Examined

Why this matters

Alternate airport planning is essential for ensuring a safe outcome if your destination becomes unavailable, directly impacting passenger safety and operational reliability. Good planning prevents fuel emergencies and supports sound in-flight decision-making.

Alternate airport planning ensures that, if landing at your intended destination becomes impossible, you have a safe and suitable backup aerodrome available. This process involves selecting alternates based on weather, operational status, fuel requirements, and regulatory rules. Correct alternate airport planning is a core skill for safe, compliant, and efficient flight operations.

Quick Check

When planning for an alternate airport, which factors must be checked for the alternate's suitability under EASA rules?

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In depth

Explanation

Key Principles of Alternate Airport Planning

Choosing an alternate airport is not just a regulatory formality—it's a proactive safety measure. The selection must consider:

Weather minima: The alternate must meet forecast weather criteria at the expected time of arrival.
Operational status: Confirm opening hours, NOTAMs, work in progress, available navigation aids, and any special procedures or obstructions.
Facilities: Ensure the alternate supports the required approach types and has necessary services (e.g., fuel, fire cover).
Regulatory compliance: EASA alternate airport rules dictate when alternates are required and what criteria they must meet, including for isolated aerodromes and predetermined point (PDP) fuel planning.

Fuel Planning for Alternates

Accurate alternate airport fuel calculation is critical. You must determine:

Trip fuel to alternate: Based on distance, wind, and expected landing mass at the alternate.
Contingency and final reserve fuel: As per EASA policy, including special rules for turbine and piston aircraft.
Additional fuel: For holding, expected delays, or other operational considerations.

Special Cases

Isolated aerodromes: If the nearest suitable alternate is so far away that alternate and final reserve fuel exceeds 2 hours at normal cruise (for turbine aircraft), special planning rules apply.
Predetermined point (PDP): For some routes, you must plan so that, upon reaching a specific point, you have enough fuel to continue to either the destination or the alternate.

Practical Steps

Check NOTAMs and AIP for the latest status of all candidate alternates.
Verify all required navigation and communication facilities are operational during your ETA.
Use aircraft manuals and flight planning tools to calculate fuel requirements, always using landing mass at the alternate for accuracy.

Exam Focus

Expect questions on how to choose an alternate airport, calculate alternate fuel, and apply EASA alternate airport requirements in various scenarios, including isolated aerodromes and PDP procedures.

The essentials

Key Points

Alternate airport planning is mandatory for most commercial flights under EASA rules.

Alternates must meet specific weather and operational criteria at the expected arrival time.

Fuel for the alternate is calculated using distance, wind, and landing mass at the alternate.

Special rules apply for isolated aerodromes and predetermined point (PDP) procedures.

Always check NOTAMs, AIP, and facility status for all alternates.

EASA requires minimum fuel reserves for alternate planning, differing for turbine and piston engines.

The alternate must support required approach types and have adequate services.

Watch out

Exam Traps & Typical Mistakes

Assuming any nearby airport qualifies as an alternate without checking weather or operational status.

Calculating alternate fuel using departure or destination landing mass instead of the alternate's landing mass.

Forgetting to include contingency and final reserve fuel in alternate fuel calculations.

Misapplying isolated aerodrome rules—these only apply if the nearest alternate is over 2 hours away (turbine aircraft).

Overlooking NOTAMs or temporary facility outages that could disqualify an alternate.

Test yourself

Example Exam Questions

Question 2Medium

For a turbine-engine aircraft, what is the minimum final reserve fuel required when planning to an alternate airport?

Question 3Medium

When calculating fuel to the alternate, which data must be used to enter the Aircraft Operating Manual?

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