Adequate vs Suitable Aerodrome: What Is the Difference?
Flight planning uses both words, and they do not mean the same thing. An aerodrome can be adequate and still not be suitable for a particular flight.
Adequate aerodrome
An adequate aerodrome is one that can handle the aeroplane in principle: the landing performance requirements can be met and the aerodrome has the facilities needed. For EDTO en-route alternates, requirements include, but are not limited to, at least one approach aid and a minimum rescue and firefighting category of 4. Adequacy describes the aerodrome and does not change with the weather.
Suitable aerodrome
A suitable aerodrome is an adequate aerodrome where, for the anticipated time of use, weather reports, forecasts or a combination of both indicate that the weather will be at or above the required aerodrome operating minima, and runway surface condition reports indicate that a safe landing will be possible.
The difference in one line
Adequate describes what an aerodrome can do. Suitable describes whether it can be used on this flight, at this time, in this weather.
Why the time of use matters
Weather is checked for a window around the time the aeroplane could arrive at the alternate. An aerodrome that is suitable at 10:00 may not be suitable at 14:00 if fog is forecast. Planners therefore check the forecast for the whole period when the alternate could be needed.
Where it appears
- Choosing destination and en-route alternates for a flight plan.
- EDTO planning, where the list of adequate en-route alternates is set for each route, and suitability is checked against weather and runway conditions for each flight.
Always follow your authority's and operator's exact definitions and minima.
FAQ
Can an aerodrome be adequate but not suitable?
Yes. If the forecast weather is below the required minima, or the runway condition makes a safe landing doubtful, an adequate aerodrome is not suitable for that flight.
Who decides which aerodromes are adequate?
The operator selects them according to the State's rules and its approval, and they are listed for each route.
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For training and reference only. Check official sources before any real flight.