I have done this many times, got caught out being complacent.
I was leaving a planet. boosted. turned off FA so it would continue on its own while I did something else ( make a brew
). while I was away I heard my ship. BANG it had nose dived on its own and rammed the planet so hard my A+ 3 SB's shields disintegrated. lucky for me I had military grade hull and hull reinforcement package. bounced of planet with 12% hull left. I had to return to base, red-faced due to me only just leaving. then on my way back I saw a NPC do the same twice. lol that cheered me up. its not just me to make a boob 
I was leaving a planet. boosted. turned off FA so it would continue on its own while I did something else ( make a brew