How to Get the 'No Fly Zone' Achievement in Halo: Combat Evolved Anniversary

Continuing the theme of "Let's get a bunch of achievements on the 'Halo' level", the 'No Fly Zone' achievement should be cake for seasoned Halo veterans. All you do is destroy three out of four banshees on the level "Halo", as demonstrated by the Achievement Hunters below.

I remember that once, I shot down a banshee on this level and I had the option to pilot it. Has this happened to anyone else, or am I going insane?