In 2010, an office building burned out of control in Austin, Texas. What triggered the blaze?
The pilot, Joseph Stack, deliberately flew his single-engine plane into the building because it housed the Internal Revenue Service.
Prior to his suicide mission, he posted this message online: "Well, Mr. Big brother IRS, take my pound of flesh and sleep well."
In 2007, a house in Indiana was torn apart when a small plane smashed into it and it was no accident.
Eric Johnson was in the midst of a bitter divorce with his wife, Beth. He boarded a single-engine plane along with his eight-year-old daughter, Emily, then took to sky, and deliberately crashed his plane into his mother-in-law's house, killing himself and taking his daughter with him.
His mother-in-law's house is right next to a runway. Instead of coming in for a landing, he crashed into the home.
This week's disaster in the French Alps has people wondering why any pilot could deliberately crash a plane.
In 1999, an Egypt Airlines flight was deliberately crashed by a co-pilot off Nantucket, killing 217 people.
And two years ago, a Mozambique Airlines plane bound for Angola was intentionally crashed by the pilot, killing all 33 on board.
It's still a rare occurrence. Over a ten-year period, only eight were determined to be suicides according to the FAA. Of those eight, all the pilots were men, aged 21 to 68, four had been drinking, and two were on anti-depressants.
Psychiatrist Gail Saltz told INSIDE EDITION, “Depression is an illness that does change your judgment, and it does change the way you think."
A depressed pilot who wore a paper bag over his head to conceal his identity, became an internet sensation in 2010.
With a bag over his head, he said, “I am forced by society to hide my face in shame."
Then, he revealed himself on INSIDE EDITION and declared “I am the Prozac pilot."
Collin Hughes walked away from his high-paying job as a charter jet pilot five years ago because he was diagnosed with depression. At that time, the FAA barred anyone on anti-depressants from flying.
He left us with a chilling thought when he said, "There are thousands of pilots who suffer from depression."