A good place to do this is Aeropuerto General Benítez in the far southeast section of the map on Islas Intichayes. There are always a few planes coming and going, and you need to chase one down and run into it in your own plane. The plane you crash into must actually be in the air; I did try crashing into a jet that was taxing on the runway, and it didn't pop. You are allowed to get killed by the explosion, so don't bother trying to eject. The achievement should pop as soon as you crash.
A faster military plane will make this easier since you might be able to run down any plane in the sky with a fighter jet. However, I was able to get a head-on collison to unlock the achievement by just taking a slow passenger jet. The eastern runway seems to usually be for landings, and the planes tend to come in from the south. So you can circle around the airport and keep flying over that runway from north to south. The next time you see a plane coming in for a landing, just smash into it before it can complete its landing.