Hi, thanks for the response.
At least now I know why my flight plans wouldn't work in some aircraft. I did convert the example flight plan from the original post ECHQ > EINN and with 7 letter coordinates it really changes the flight and you spend as much time fixing as converting.
All this was to get a waypoint based flight plan to work in the Salty stable B747 which currently doesn't accept 11 letter coordinates. The Salty development B747 version does.
The Example flight becomes (and route looks very different):
EGHQ N0490F260 50N005W 50N005W 51N005W 51N005W 52N005W 52N005W 53N006W 53N006W 53N007W 53N007W 52N008W EINN
7 letter coordinates are just too inaccurate for flight planning and I presume the 5 letter method would be worse. So sticking to 11 letter is best.
I will be downloading the development salty b747 to test this all out.
Thanks for all the work your doing, little navmap is great.