Flew from N Yorks to Boston today. Part of route was throgh the stub between Cranwell and Coningsby. I particularly noticed a difference of some 0.5 miles between Garmin (Jeppesen) and SkyDemon re the southern stub boundary. According to SD I reached the s Boundary about 0.5 miles before Garmin said so. One has to be wrong. Pains me to say it but suspect Jeppesen is correct.

Other than that 8410/SD worked flawlessly.

Also location of my home field, Husthwaite is wrong in SD. I know this because when you are on the runway, airfield loaction on SD is about 0.3 miles south.

Conversely, all roads are exactly right  .. going by test when just driving about.

Any thoughts Tim?

David

Thanks for this. As you see this has caught my imagination. Have done some checks as you suggest and I realise it does not matter much anyway as MATZ boundaries are not legal for us and you explained they do not have proper co-ordinates.

Doing some checks, I conclude as follows:

1. Proper CTA boundaries are in right place! Checked this via road intersections and co-ordinate cross check with MM, 1/2 mill chart. As I and you expect.
2. But while the 7mile/83 & 2NM 174 test does indeed give a leg length of 2.0 miles on your map, distance to the boundary on Flitestar (Jeppesen) is some 2.2NM. On MM its a bit over 2NM but say 2.1.
3. However, having got me interested, I then looked at the width of your MATZ stubs. On my screen at least, I wd say yours are almost all around 3.8NM. Difficult to make many = 4NM.

But in the scheme of things very trivial I accept. Just need to be aware that there may be differences re MATZ boundaries when exporting routes to Garmin.

D