Call for Science: Avenger Defense UFO

[trihero]

Despite a year of playing vanilla xcom and a few months of xcom 2, and despite many google searches and info digging, I have never figured out how the UFO detection mechanics work with great specificity. If someone has the specific information on what determines the flight time and chance to evade that would be lovely (maybe it's already known but I missed it somewhere) but in the mean time how about we as a collective get a better feel for it by recording data?

If you wish to participate, it's simple. As you're going through your 1.3 playthrough, remind yourself to write down the date at which the UFO spawns, and then the date at which the UFO catches up to you, and then whether you evade it or you had to to the defense mission. If you wish, you can list the difficulty, but I have a feeling that doesn't affect flight time/chance to evade since I'm guessing the difficulty really just affects the mission's difficulty itself.

Things which I consider irrelevant/already known: we know there is a chance to spawn the UFO after a forge/blacksite/gate mission. Not interested in that knowledge. If you wish to make a comment like "well when the UFO is out there you should be prepared with your best team at all times," this is also unsubstantive and unhelpful with answering the question at hand. I'm not concerned about how to beat or prepare for the mission, I've done it plenty of times, and there are many other threads on the tactical layer. I am interested, and I think a lot of other people are interested, in knowing when is the most likely time to get caught (flight time distribution). I have a feeling there is a minimum time as I've never had it happen before 7 days, but that is complete conjecture, and I think it's more likely to happen at the maximum flight time than not, but this is also conjecture and could be confirmation bias since I just happen to remember the the times when the UFO drags out and waits forever and forever.

Knowing this information can help us better allocate troops instead of wasting too much time holding them back during the threat of UFO.

Interestingly as a side note, in the 1.2 notes it said the max flight time is 14 days but this is demonstrably untrue as I submitted a bug report based on the following data which I collected a few days ago from my 1.3 rookie playthrough (the following is the kind of data I would like to see in the following posts unless you have hard evidence from the code itself)

UFO Spawn date: 10/30
UFO Attack Date: 11/20
Status: Did not Evade (avenger defense activated)

[trihero]

UFO spawn date: Sept 26th
UFO attack date: Oct 9th, evaded

[Dwarfling]

Spawn: Jun 25th
Attack: Jul 8th

[gimrah]

Recommend you ask participants to specify whether it's a DE ufo or a plot mission triggered one. (I haven't had one yet.)