One way of thinking about altitude is how many mistakes you have time to recover from before hitting the ground. The higher you are the safer you are - you haven't crashed until you hit the ground.
For a single-engine plane, 500' AGL depending on the plane and wind is enough to make a 180° turn and land on the takeoff runway if its clear. 1000' AGL will let you do it on just about any suitable surface at the airport - other runways, taxiways, grass clearings adjacent to them, etc - and give you a few seconds to be confused before deciding that you need to make an emergency landing.
Most birds fly quite low, and drone-based bird abatement at airports would be a safety win if done right (DO-178-B style software quality), but I've heard of bird strikes above 20,000', and been taught to expect that you're never flying above _all_ the birds.
Edited to reply directly to your 3000' comment like I meant to: At 3000' AGL, you can almost always glide to a safe landing point, unless you're over mountains or a dense urban area. But unless you happen to already be near an airport, you probably won't be able to glide to one. Glide ratios much higher than 10:1 are uncommon, so thats 5.7 statute miles. Lots of places are more than 5.7 miles from an airport.
That's pretty mind blowing. The top of the list there is Rüppell's vulture, which was confirmed in 1973 to have been flying at 37,000 ft, identifiable by feathers it left behind when it was ingested by a jet engine.
Unlucky bastard. You think you're safe, 7 miles above the earth, far from any predator, when WHAM. At least it was a quick death.
For a single-engine plane, 500' AGL depending on the plane and wind is enough to make a 180° turn and land on the takeoff runway if its clear. 1000' AGL will let you do it on just about any suitable surface at the airport - other runways, taxiways, grass clearings adjacent to them, etc - and give you a few seconds to be confused before deciding that you need to make an emergency landing.
Most birds fly quite low, and drone-based bird abatement at airports would be a safety win if done right (DO-178-B style software quality), but I've heard of bird strikes above 20,000', and been taught to expect that you're never flying above _all_ the birds.
Edited to reply directly to your 3000' comment like I meant to: At 3000' AGL, you can almost always glide to a safe landing point, unless you're over mountains or a dense urban area. But unless you happen to already be near an airport, you probably won't be able to glide to one. Glide ratios much higher than 10:1 are uncommon, so thats 5.7 statute miles. Lots of places are more than 5.7 miles from an airport.