This is just a new way of limiting an elapsed time task. Normal way is to set close for task (or tps) at a given time of the day.
You need to set it relative to the pilot’s start-time.
Would it be ok to use the last time a pilot leave the (first) turnpoint as start-time?
The task definition would then be either “Elapsed time” or “Open distance”.
The addition will simply be a field for spesifying max elapsed task time.
The difference from what you’re asking is that we do not attempt to find out when the pilot leaves the ground. So the pilot is free to start the task at any time once of the ground (just like any ordinary elapsed time task).
Stein-Tore