It's the long suppressed Philadelphia Experiment scenery!
No, seriously, Pete's right. It's "unique" file names that aren't really unique.
In order to have add-on scenery that doesn't conflict, it's necessary that every scenery object have a unique file name. This doesn't just mean unique names for each BGL file; it also means unique names for every object contained within every BGL file. If you peek inside any BGL file you'll see that the included library objects have very long file names composed of long strings of nonsense letters and numerals.
When multiple developers are creating scenery with the same software, duplication is avoided by having those long strings of characters assigned by a random character generator built into the modeling software. When these objects are created and assembled, the software assigns those long identifiers. With so many characters, both letters and numerals, the odds of two objects getting the same name is almost nil. I read somewhere that the probability of that happening is less than once within the anticipated lifetime of the physical universe.
Yeah, well as our understanding of randomness tells us, just because something might average one occurrence every umpteen gazillion centuries, that doesn't mean it won't happen for that long every time. That would be very orderly, and random is the opposite of order. There's nothing that says it can't happen twice in the same afternoon, then not again for however many times umpteen gazillion centuries.
In fact, this happened within a few years of FS9 being released. We saw it back then. I remember the screenshots of ships in the desert. On the flip side, I had jetways floating in the ocean among the Virtual Navy's Task Force 16. I don't know what Israeli airport scenery was involved, but I'm pretty certain that the ships come from TF16.
If you don't have TF16, then the ships must come from somewhere else. Likewise, if you don't have any airports in Israel, then this is a new occurrence, not a repeat of the earlier one.
There's an easy way to test this. Simply reverse the order of the two sceneries in your scenery stack. If the conflicting sceneries are the ones I propose, then you'll find no ships at that airport, but you'll find jetways floating in the ocean among the ships of TF16. For an even quicker test, just inactivate TF16 and see if the ships disappear from that airport.
If you just have one installation of FS9 (like I did when the problem first appeared) there is no permanent solution to this conflict, but there is a temporary one. When you're going to fly to or from that airport, deactivate the TF16 scenery, and if you're going to fly to or from TF16, inactivate the airport scenery.
If you have multiple FS9 installations depicting different time periods (like I do now) then you probably want TF16 in a WW2 era sim and maybe a Classic Era sim, and that modern airport in a modern sim. I have multiple sims like that, I just went into the AddOn Scenery folders of my old timey sims and deleted every BGL file that had the word jetway in its file name. I just used Windows search mode to search for "jetway" and deleted everything it found. They didn't have jetways at WW2 or classic era airports, so nothing I wanted was lost. Likewise, there were no task forces of straight-deck carriers in the period covered by my Jet Age sim, so I don't have TF16 in that one.
I might mention that I don't have any Israeli airports in any of my FS9 installations, but back in the days when I only had one FS9, I still had jetways in the ocean, so apparently the guilty jetway bgl is also included in other airport sceneries. That would suggest that you might have ships at other airports too, though I have no ideas which ones.