Scott D. wrote in message
...
Another thing to think about is, could they have been practicing a
simulated engine out and setting up for an emergency landing, then
recovering at 500 agl.

I don't see how that would be legal in a congested area. Unless you intend
to land, you're not allowed below 1000' AGL. (Flying a low approach over a
runway appears to be an unwritten exception to this rule, however.)

--Gary