Last week I accidently witnessed several planes getting stuck mid-air, while constructing an other, unrelated airport, which these planes were just overflying.
Since then I run some tests to verify this observations and was able to reproduce this incident with different plane types, see also the video below.
Planes happen to be caught on an unrelated strip/tile of taxiway when overflying it after it's next adjacent tile has been just lowered or raised. The respective plane has to have already left their last halt before the terrain modification occurs.
This plane is/planes are "caught" as they immediately loose their route and become unable to find a new one. At this stage, they also can't be reset or otherwise made to continue their flight or to return to their departure airport.
Further remarks:
- While planes are stuck over the taxiway in this manner, they can be "removed" with the destroy/remove tool (or the remove taxiway/runway tool, when applying it to only this one tile).
- After disappearing in this odd way, they can eventually re-appear randomly (from a time-space-fracture I assume ;D ), if the taxiway tile is then removed too.
After a random number of seconds they then suddenly reappear. I always observed this within less then a minute. - Planes still can be removed regularly through their vehicle's window 'remove now' button, afterward they disappear immediately and never come back, as is the normal behavior.
- When trying to reproduce this behavior with runways, instead of taxiways, planes just "bump" in to, and "bounce off" the highth-altered tile but then continue their journey, if the runway is only two tiles long. When it's longer planes just kind of "bump" into thin air, but suddenly can be find on this very runway taking off again and proceeding to their original destination
- When trying to reproduce this behavior by only modifying the terrain, planes don't even bump no more, but hover a split second in place and then continue their journey.
PS: I am aware, that it is a very specific bug, wich IMHO can be directly moved to the 'known bugs' section.
( the former message was moved from here to the original post, above, and added there )
They will reappear after searching the whole map for the tile they should have been. That can take a while.
Fixing that was easy. But one should not be able to delete flying airplanes. That bug was more work to fix. See r11332
Cool! Thank you for addressing this issue :)