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Airmann
1st Aug 2019, 15:28
In the notes for Manchester Airport there is a note regarding the turning pads, which mentions that they are suitable for aircraft "up to a ....." And the aircraft are A380 for one runway and the B767 for the other. What exactly does it mean when it states that it is suitable for aircraft "up to" a given type? Does it mean the wing span? Weight? Gear Spacing?
Thanks

DaveReidUK
1st Aug 2019, 19:49
In the notes for Manchester Airport there is a note regarding the turning pads, which mentions that they are suitable for aircraft "up to a ....." And the aircraft are A380 for one runway and the B767 for the other. What exactly does it mean when it states that it is suitable for aircraft "up to" a given type? Does it mean the wing span? Weight? Gear Spacing?

The usual way that airports express limitations like that is to specify the ICAO Aerodrome Reference Code letter, which is based on a combination of wingspan and outer main gear wheel span.

So "up to A380" would mean aircraft with code letters A to F (span < 80 m and gear < 16 m), whereas "up to 767" would be codes A to D only (span < 52 m and gear < 14 m).

KingAir1978
2nd Aug 2019, 18:44
If I remember correctly from an aerodrome design manual that I've glanced over, a margin of 4,5 m on each side of the main gear is required to certify a taxiway. So, for example a Code E airplane has a maximum wheel base of 12 meters, thus requiring a taxi way that is 12 + 4.5 + 4.5 = 21 meters wide.

Airmann
2nd Aug 2019, 19:03
So why didn't they just mention the aircraft code rather than a specific type? Of course I know how big my aircraft is in relation to the 767 but is that a requirement for pilots? Just seems strange way to present the limitation.

DaveReidUK
2nd Aug 2019, 19:06
If I remember correctly from an aerodrome design manual that I've glanced over, a margin of 4,5 m on each side of the main gear is required to certify a taxiway. So, for example a Code E airplane has a maximum wheel base of 12 meters, thus requiring a taxi way that is 12 + 4.5 + 4.5 = 21 meters wide.

Yes, per Annex 14 the recommended margin for Code D/E/F aircraft is 4.5 m either side of the outer main gear.

For Code E aircraft (gear width < 14 m), the recommended taxiway width would therefore be 23 m.

gatbusdriver
3rd Aug 2019, 14:21
So why didn't they just mention the aircraft code rather than a specific type?

Maybe because there is an assumption that some out there don't realise what code F means, but you are right, that would be the best way to describe it.

DaveReidUK
3rd Aug 2019, 16:43
Maybe because there is an assumption that some out there don't realise what code F means, but you are right, that would be the best way to describe it.

Particularly as the current Manchester AIP contains other references to codes D, E and F.

Airmann
4th Aug 2019, 01:27
Maybe because there is an assumption that some out there don't realise what code F means, but you are right, that would be the best way to describe it.

Might be. I see a lot of airports refer to aircraft limitations by wing span rather than code. But I wonder if that is because code includes wing span and wheel spacing and the airport is only interested in span limits?

DaveReidUK
4th Aug 2019, 08:28
Might be. I see a lot of airports refer to aircraft limitations by wing span rather than code. But I wonder if that is because code includes wing span and wheel spacing and the airport is only interested in span limits?

If the main concern is wingspan, it still makes sense to use the code letter.

The only reason I can think for using actual wingspan is if an airport needs to make a finer demarcation than the code letter allows - for example code D (FAA Group IV) covers a huge range of spans from 36 m (118') to 52 m (171').