Military AI Works

Recently I have been experimenting a bit with making my own traffic flight plan files. I like to review what has been done before me since you guys are the masters in this domain) and I notice that all these flight plans have a specified ETA time listed. There is something entered in the ETA Override Box, and I never understood why.

What is the reason for doing this? What negative AI behavior does this help alleviate or avoid?

I have read the section(s) that Don G wrote in his AIFP manual on the 37-minute rule, aircraft arriving late (in some cases) and all that.

There was something also about a 22 minute offset -- from DON:

" If AI traffic is more than about 20 minutes late, it is discarded. From extensive testing (by others), it has been determined that the critical time difference is 22 minutes. Given the standard 15-minute allowance for approach, landing and taxiing, the 22-minute interval equates to 37 minutes later that a user-specified arrival time. Hence, the name “37-minute problem. "

OK so now I go back and open a traffic file and sure enough, this one is showing an ETA override of 22 minutes early - as compared to what AIFP calculates.

So is that it then? Is this just considered a best practice here, so that we reduce or avoid this problem of aircraft being delayed and disappearing?

Just use AIFP calcs and then slice off 22 minutes as an override in the FP? This works best?

I will stick with AIFP here as this is what the query is based upon.
There are basically two ways to program a flightplan. Use a specific time to arrive or use a journey time.

If you are using a timetable, i.e. airline schedule, then a lot of people use the arrival time preceded with a '@'. What this does is mean that the aircraft will fly as fast as necessary to arrive at that time. Useful for airline traffic but not for formations of military traffic.
The second form is the basis of AIFP in that it works out the arrival time using the cruise_speed in the aircraft.cfg.

Now the caveats here are that AIFP does NOT use the speed in the aircraft.txt but what is in the aircraft.cfg. The airliner plans, i.e. ones with a '@' also have a convention that the speed is set to 200 KIAS. This is so that airliners would not overtake each over in flight, just like real life.

The 37 minute rule relates to an aircraft being late. It does not matter about which method you use. If it breaches the threshold it will not arrive.
So looking at things logically it makes sense to use the AIFP system to set the arrival time. Whilst it can still breach the limit it is less likely to.

Finally, why do some of our flightplans have a significant period of extra time over an arrival time? This is so that some rollers or overshoots can be carried out at the destination before it is time to land.