Thanks for the invaluable feedback Glenn.
Initially the aim was to create a single 2000m plate, but as you rightfully pointed out the game doesn't like that.
Green Hell airfields use 2000m X 2000m plates.
I think single plate runways at lower lengths is possible but very difficult to get the scale and also detail close up with the texture being spread over such a large area.
The typical runway plate we currently use is 40m x 40m, with 40 or more being used to make a single airstrip.
Whereas my plate is 1000m X 50m and only 2 are required.
The whole purpose is to avoid repetition and give the opportunity of adding things like oil stains, skid marks and pot holes without seeing it endlessly repeated.
For a dirt strip like this one, a more realistic length and width would be 1200m X 30m which could be made from two 600m plates.
Having the smaller plates would certainly help detail at ground level.
It doesn't help not being able to have normal, displacement and the various other maps available to transform a flat texture into something more 3 dimensional.
I will be adjusting the Ambient setting and adding at least one more LOD in future versions so thanks for the suggestions there.
Obviously the plates have to be placed on terrain that's been leveled, will the flickering go away if it was given a hook and/or align to land?