our city says 4750, and there is plenty of signs around as you drive that say 5200 and similar, about 20 minute drive there is one that says 7000, its a curvey mountain switchback, but yeh i think were pretty high, i still get short of breath moving to quik(haha), i think the fx91 may be just enough if i prop it right, it spins a 15-6 pretty good, i see there is a 16-4w apc out there too, i think that would be perfect, i don't think it would be a rocket, but as long as i could hover down low and harrier the rudder to scrape along my runway i'd be happy, i'll have to check out that flip, i think it was 259 last i looked, so it was a really quick look