Hi all Hit a problem I've never seen before in FSX today, and Google doesn't seem to yield a single result with quite the same issue I'm having. I bought PMDG's 737 NGX earlier tonight, and flew two brief 10-15 minute unplanned flights, just to get a feel for it. (Beautiful plane!) Then I went to try a somewhat planned flight. Wanted something short, so I jumped to Knoxville McGhee Tyson (KTYS). Forget which gate, but I know it was a "medium" one. Sat at the gate and fiddled with setup for 5-10 minutes, and then suddenly got a spontaneous "building crash". "Strange", thought I, but I reloaded, and noticed that by default the PMDG was loading without the parking brake set. Figured maybe it inched forward on idle and touched the building, so I set the parking brake and got back to repeating my setup work. This time, after only ~90 seconds or so, I got another building crash. It reloaded, and this time gave me a building crash immediately on a black screen (never drew anything of the airport or plane before the message), then FSX locked up altogether. This time the exact message was "You are starting in a location in which your aircraft will collide with another object. Choose a different starting location." Switched to my desktop and there was a rather bizarre popup stating "This feature requires that (smartassembly) is available on this computer". Acknowledged, restarted FSX, set up the same PMDG plane at KTYS, but this time on the active runway, and... you guessed it. Instant building crash message without ever trying to draw my location. Acknowledged and it bombed back out to the FSX startup menu, then threw up a repeat of the "building crash" message. Acknowledged it, tried to choose another airport, realized the FSX interface was locked up. Reloaded FSX, tried a different plane (Ant's Airplanes Tecnam Sierra) at KTYS on the active runway. Instant building crash, menu, building crash, lockup. Reloaded FSX, tried a Microsoft stock bizjet at a random airport I'd never been to. Loaded fine. Changed location to KTYS active runway. Building crashes and lockup again. The problem seems to be specific to KTYS, an airport I use frequently in FSX and have never had a problem with before. I haven't installed anything new into FSX (not even an AFCAD) in months, except for the PMDG 737 NGX, and McPhat's liveries for the FeelThere ERJ v2. So, I'm wondering... perhaps has a file related to KTYS specifically gotten corrupted? And if so, is there any way I can repair it without reinstalling FSX completely from scratch? I've not got a *huge* number of addons, but I do have a fair few as in my sig below, and I've never reinstalled since buying commercial addons, so I'm concerned about whether any of them will balk at being reinstalled -- especially my brand-new PMDG NGX which was only first activated a couple of hours ago. I don't honestly know if I need to deactivate addons somehow before uninstalling FSX, like I'd need to do with, say, my Photoshop plugins before reinstalling Adobe Photoshop. If it's at all possible to fix the problem without reinstalling, I'd like to do so. If not, and my only alternative is to reinstall everything, I'd be grateful if anybody experienced with the process can chip in with advice about what I need to back up, whether addons typically would need to be deactivated, or whether I'm going to need to contact each addon manufacturer before starting the deinstall / reinstall process to find out how I need to proceed. Thanks in advance for anybody who can offer assistance, as well as those of you who've no advice to offer, but took the time to read my thread and see if you could help. :-)

This is a common problem in FSX with crash detection turned on. It's one of the reasons why I turn off crash detection. I have enough frustrations on the golf course! I doubt you have a corrupted file. That's rare. I see you have Ultimate Traffic 2 installed and that's probably your problem as these AI programs usually issue an AFCAD that will work with their AI program as they develop flight plans for their AI aircraft. I don't have UT2 (well I do, but it's not installed) but use MyTrafficX. In the scenery library I have MyTrafficX located just above Propeller Objects. That way it gets loaded first and any scenery program after that (higher up in the scenery library) gets loaded afterwards and trumps any AFCAD issued in MyTrafficX. MyTrafficX has a bunch of AFCADS in the MyTrafficX/Scenery folder in the main FSX directory and sometimes I go in there and rename a conflicting airport. You may have a similar situation with UT2. You can also try disabling UT2 in the scenery library and see if that fixes your problem. I have also heard that some FS9 developed scenery is not fully compatible with FSX so, if you added scenery for this area in Tenn, that could be your problem too. Having your scenery sliders all the way to the right will also raise the areas around and on an airport too and that might cause an object, like autogen, to be higher than it was developed for FSX. There's no "magic bullet" to fix your problem (other than turning off crash detection). You'll have to investigate your system, your programs and your FSX setup on your own but at least you have some idea where to investigate. You'll have to take the knowledge of your search results in Google too to find a solution. Do a search for invisible building crashes. Best regards,Jim

I have my crash detection off as well, it gives too much headache. Like for example I was taking off, and I got clearance from the tower of course, but when I reached about 1/3 of the runway, I noticed an aircraft on the runway, heading right at me! Apparently, it just landed, but since I had crash off, I just went through it.

I have my crash detection off as well, it gives too much headache. Like for example I was taking off, and I got clearance from the tower of course, but when I reached about 1/3 of the runway, I noticed an aircraft on the runway, heading right at me! Apparently, it just landed, but since I had crash off, I just went through it.

Sometimes I'll set myself up on a ramp at an airport before taking off with my iFly or PMDG 737 and find myself surrounded by aircraft under my wings and behind me, and, in this case, I would have a crash immediately after FSX loaded. Maybe this feature will work better in future versions of flight simulator. Maybe not.... Best regards,Jim

Sometimes I'll set myself up on a ramp at an airport before taking off with my iFly or PMDG 737 and find myself surrounded by aircraft under my wings and behind me, and, in this case, I would have a crash immediately after FSX loaded. Maybe this feature will work better in future versions of flight simulator. Maybe not.... Best regards,Jim

Hopefully it's something they'll improve, Jim! I'm curious how will Microsoft Flight turn out to be.

Hopefully it's something they'll improve, Jim! I'm curious how will Microsoft Flight turn out to be.

I think everyone is anxious to see the improvements. It's not only building crashes but when you set your realism settings high and try to fly a commercial 747 like PMDG's, you'll most likely get a crash somewhere in the flight as too much stress was placed on a wing and I find that frustrating too. You spend 10-15 minutes setting a flight up, programming the FMC, take off, turn on Autopilot and the aircraft most likely crashes somewhere along the flight path telling you too much stress was placed on the wings. Even in Autopilot! No fun.... Best regards,Jim

I think everyone is anxious to see the improvements. It's not only building crashes but when you set your realism settings high and try to fly a commercial 747 like PMDG's, you'll most likely get a crash somewhere in the flight as too much stress was placed on a wing and I find that frustrating too. You spend 10-15 minutes setting a flight up, programming the FMC, take off, turn on Autopilot and the aircraft most likely crashes somewhere along the flight path telling you too much stress was placed on the wings. Even in Autopilot! No fun.... Best regards,Jim

Oh that is very annoying! It has happened to me numerous times. I ended up wasting 2-3 hours just TRYING to do a flight. Like you said you spend 10-15 mins prepping, then taxiing and lining up another 10. You take off, everything is good, fly for like 20 minutes and boom... flight wasted. That's definitely something they need to improve vastly. Regards,Matt.

I don't think "crash detection" really adds anything to the sim for me. The problem is 3d objects use a bounding box and then test to see if the user is intersecting with the box. Using the exact geometry would greatly increase the amount of math required to make the determination. scott s..

I've been having crash detection problems for some time now, at places where it never used to happen all of a sudden I crash into nothing, and even worse I've had building crashes at 3500 feet, work that one out. It's a pain but I do prefer to have crash detection switched on, I don't like airplanes that bounce off runways when they should have crashed, you don't know then if you came in too hard.

I've been having crash detection problems for some time now, at places where it never used to happen all of a sudden I crash into nothing, and even worse I've had building crashes at 3500 feet, work that one out. It's a pain but I do prefer to have crash detection switched on, I don't like airplanes that bounce off runways when they should have crashed, you don't know then if you came in too hard.

Actually, ATC will tell you indirectly if you crashed by NOT telling you to take the next exit off the runway (if you landed under control of ATC). ATC will remain silent. When you do select ATC for parking to the gates, you'll get directions even while on the runway. Normally ATC will not give you a Gate until you are completely off the runway. There are also commercial programs, like XPAX from HiFi Sims and FS Passengers, that will tell you how you landed too. Best regards,Jim

Thanks for the info, folks. Been a busy week, not had time to look into this any further yet. The strange thing, to me, is that this problem has suddenly appeared out of nowhere without me installing any new scenery, AFCADs, etc. -- the airport has been working just fine for months. Literally the only things I've installed recently are completely unrelated (liveries for one aircraft model, and another new aircraft model). And the problem occurs with models completely unrelated to those ones. And then, what makes it really, *really* weird is that I'm getting a building collision immediately upon starting *on the active runway*. Note, that's not an aircraft collision (I have those disabled) -- it's a building collision somewhere that's nowhere near any buildings. I may, I guess, be forced to disable collisions altogether next, and see if that fixes it. It seems to me, though, that this must surely be some sort of corruption, because it doesn't seem logical that the problem wouldn't have suddenly started happening 100% of the time on one single airport and runway I use regularly, with nothing relevant having been installed or changed. I presume there must be a file (or set of them) specifically related to the airport, and wondered if there was perhaps some way to extract just that file (or files) from the FSX install media... Although maybe I shouldn't expect FSX to be logical. ;-)

"and wondered if there was perhaps some way to extract just that file (or files) from the FSX install media..." Unfortunately you cannot extract a file from the FSX DVD's as in previous versions. The only method available is a "repair". I doubt there is corruption. Just moving some sliders under the scenery tab will lower or raise airport elevations. It could be as simple as that. FSX has a lot of "issues" that will not be corrected in this version. This may be the first time the problem at Knoxville has come up as I assume not many people fly in/out of Knoxville, and, if they do, they have crash detection turned off. Perhaps you can edit the AFCAD for the airport (if you can find it) and remove the obstacles. I'm sure there are many more airports that has this same problem and has yet to be discovered. Just thought of something -- what are you autogen settings? Above normal? Does the problem exist with autogen turned off? Best regards,Jim

"and wondered if there was perhaps some way to extract just that file (or files) from the FSX install media..." Unfortunately you cannot extract a file from the FSX DVD's as in previous versions. The only method available is a "repair". I doubt there is corruption. Just moving some sliders under the scenery tab will lower or raise airport elevations. It could be as simple as that. FSX has a lot of "issues" that will not be corrected in this version. This may be the first time the problem at Knoxville has come up as I assume not many people fly in/out of Knoxville, and, if they do, they have crash detection turned off. Perhaps you can edit the AFCAD for the airport (if you can find it) and remove the obstacles. I'm sure there are many more airports that has this same problem and has yet to be discovered. Just thought of something -- what are you autogen settings? Above normal? Does the problem exist with autogen turned off? Best regards,Jim

Hi Jim: thanks for the reply, in the interim I'm flying with crash detection turned off, now. What everybody seems to be missing, though, is that nothing was changed in FSX for the problem to show its head. All my scenery sliders are as they've always been, crash detection was always enabled, I've not installed any AFCADs or scenery in months, and I've used this airport very regularly without issue (it's probably the most or second-most common airport I fly from, as in the real world, it's my closest airport with scheduled passenger flights.) My autogen is set to "extremely dense", but it has been set that way for months without issue at this or any other airport with building collisions. (My PC's very capable, and with these settings it happily gives me a steady, externally frame-limited 30 fps at all but my most complex scenery (FlyTampa Kai Tak), and even there it's perfectly flyable.) I just tried disabling autogen altogether and reenabling collision detection, though, and got an instant building collision on the active runway with a stock MS aircraft.

As a followup to the above, I just tried dropping all my graphics settings to the absolute lowest possible, with the exception of resolution. I also replaced the files for my third-party KTYS scenery (I'd forgotten I had one, actually, it's been installed for so long) with a fresh copy, to be sure they weren't corrupted, and disabled / reenabled that scenery to make FSX rebuild its scenery database. I still get the instant building crash on the active runway. Strangely, if I disable that KTYS scenery, I no longer get the building crash. I say strangely because I've been using it for months now without problems. Since I know the third-party scenery hasn't gotten corrupted, I'm thinking something has to have happened to the stock scenery in the same area which now causes it to interact badly with the preexisting third party scenery. Not sure what, though...

I've had crash detection turned off for years. It takes a load off the CPU, giving better performance. Some add-on aircraft are optimized with CD turned off anyways, like belly landings, etc. It's been a long, long time since I've actually "crashed" in FSX anyway, and even if I did, I'd just get up and go make a sandwich in the kitchen, regardless of whether or not CD was turned on. Crash Detection in FSX is a buggy headache that also happens to demand more of system resources to calculate all the little invisible hit boxes. Turn it off.