Essentially: I have a tower on the ground. There's two ways to get into the tower. One a hidden underground entry, the other nearer being a vertibird which you can use to travel with by activating the left or right side of the control panel. One takes you to the top, and bottom of the tower, the other just for immersion without being game breaking quite takes you near Goodsprings, and back. To further add on to this, there's a hidden entry you must find, to get the key to enter another hidden entry far away in the last room of enemies, and in the final room unlocked only by a key through the hidden entry, you get the keys to the vertibird. This prevents someone from exploiting the vertibird without doing some searching, or going into the more dangerous parts of the building interior. At the same time it rewards a character who can fight or sneak or (run??) their way past. With having easy access to the top, and bottom that's believable.

I also spent quite a bit of time on the interiors... It would be a real shame to lose the optional vertibird transport which is like the icing on the cake. So anyways here's what happens. Two companions follow me from ground level, to the top balcony/platform directly multiple times. And I go to ground level then back up, exiting in and out randomly to test... Things go fine. I fly to Goodsprings without getting out near Goodsprings, then fly back to both places testing. Things go fine. I fly to Goodsprings, exit, re-enter, and then fly back... Bad stuff happens. Always with the door connecting the highest vertibird to what's basically a tower. The companions stop teleporting to the top ledge, or the game freezes the second I leave the door of the top vertibird. And it seems directly related to entering, and exiting the vertibird in Goodsprings before entering the one near Novac. It it helps matters at all here's the crash report.

"Problem signature: Problem Event Name: APPCRASH Application Name: FalloutNV.exe Application Version: 1.3.0.452 Application Timestamp: 4daf4b02 Fault Module Name: FalloutNV.exe Fault Module Version: 1.3.0.452 Fault Module Timestamp: 4daf4b02 Exception Code: c0000005 Exception Offset: 0065e9c4 OS Version: 6.1.7601.2.1.0.768.3 Locale ID: 1033 Additional Information 1: 0a9e Additional Information 2: 0a9e372d3b4ad19135b953a78882e789 Additional Information 3: 0a9e Additional Information 4: 0a9e372d3b4ad19135b953a78882e789 Read our privacy statement online: http://go.microsoft.com/fwlink/?linkid=104288&clcid=0x0409 If the online privacy statement is not available, please read our privacy statement offline: C:\Windows\system32\en-US\erofflps.txt".

So if I can't figure something out, I guess I just must sacrifice the vertibirds?? I honestly don't know what's up with the cell in Goodsprings causing this, and I think I even tested it as an ESM earlier for further clarity. I'm afraid I may have to sacrifice the vertibirds? Before I do so though, I feel I should see if there's some way to figure out what's causing this, as I don't take sacrificing them from the mod I've been working on lightly.