 Here is an interesting video where these two guys take their small engine plane up and do a anti-grav dive. Now I always thought you had to have a big plane like a 747 to be able to have enough mass to get the no gavity effect but apparently I must have been smoking crack in physics class. The plane these two guys are in seems to be either a small one engine or a two engine plane. The catch is they have a dog in the back. When they hit the zero grav the dog floats up into the air and can't figure out what the hell is happening. Some of the other items in the plane also float. The dog ends up floating upside down until they come back into gravity. Oops.
Watch this dog get freaked out by zero gravity. Source: Fugly.com | 
