measure time between events



sorry if it's been asked before, but could not find it on the forum.

I'm making a simple mission for the hip (for the huey too, later) to improve the times I spend taking off, transit and land to deploy troops.
The idea is very simple, I turn on a flag as soon as I take off, then turn it off on landing in a certain zone.
On landing, a message displays the elapsed time.

My intention was to measure the time between flag 1 =on and flag 1=off, possibly up to tens of seconds.

Basically a stopwatch using the internal clock.
If it possible, I'd like to do this without scripting.

Also, if there is an even simpler way to accomplish this without using flags, I would prefer it.

I'm pretty sure that there must be a simple way, but can't find it in the mission editor.

Another thing that is not very clear to me is how to display the content of a "variable" (in this case, the elapsed time), in a "message to all" text.

Thanks in advance