So few minutes ago I was playing in Esamir at the Tech plant (don't remember how this Tech plant called but it was a bit north from the center of the map) and I saw this sundy. So now that I know about this, if this is not a hack please tell me how.
This has already been discussed very recently, to which you can find the thread here as well as the reply the OP received from customer support confirming that currently it is not a bug nor an exploit here.
All it would take to stop sunderers getting up there would be to put some vehicle bars in front of the stairs. Since this pitifully simple fix hasn't been added, then it would seem that the devs both support it AND intend it to happen even.
Not a bug, as has already been discussed in another thread. Here's the quote from the guy who spoke to Customer Service trying to report this as such:
Earlier on in the game's life, before they put the bars on the stairs in the warpgate bases, we would drive our Flashes up to the 2nd floor, out onto the roof over the terminals, and then deliberately get it stuck in the space between two roofs. After 10-30 seconds of throttling up and down, the throttle would go crazy, and the rpms and pitch would be about triple of normal. Finally, the Flash would wiggle, then violently , and then it would break loose and fly completely across the continent and actually warp to another continent, where you would find yourself and your Flash, falling from a very high altitude. Pretty wild fun. It's great fun to explore and discover those (sometimes) harmless glitches. I would love to play a game where that was the core design: Explore, screw around, mix stuff together and see what kind of weirdness you can squeeze out of it.
Lol OP you must be really new to PS2. Sundy on that point is usual. ESF inside the biolab is a bit rare but still happens. Once I've been watching a guy on a shiny mosy farming around with Banshee inside the dome for 30 min at least. Mag and Harasser can relatively easily get onto Rashnu biolab from the cliff. And you can find guides for all of that and way more. This is NOT hacking.