Remember the hiker who they found dead when the broken down car he was riding in backfired as the driver tried to restart it. The hiker fell dead straight away from a boomerang which he had thrown and was watching. When the car backfired, the hiker turned away to look where the bang came from. The boomerang killed him instantly & went into the river.
Then the mysterious man who died in the car crash was shown with Inspector Greg. The dead man must have already boarded his flight because he had a napkin and biscuit with the airline's logo on his person & I believe his passport had been stamped. However, he ended up dead in the trunk of his car very near the airport from which he was departing. It almost seemed they wanted you to think he fell from the sky.
"The Woman" Irene Adler, betrayed/tricked Sherlock by having him decode the top secret message she had obtained from a person that she "knew what he liked." Remember SHERLOCK decoded the message in a mere 8 seconds - after he heard Myecroft on the phone the day before stating that Bond Air was "a go" and it all clicked for him. It was Flight #007 (Bond Air) from Heathrow to Baltimore. Myecroft's two years of planning of the Coventry air flight of the dead was ultimately ruined by Sherlock's desire to impress "The Woman", who was feeding Moriarity critical information. As a result, Myecroft's flight of the dead never could take place. Sherlock saved Miss Adler from beheading in the Middle East and the way they did it was really slick & a great ending!!!
There were rumors there had been one previous flight of the dead that was successful during WWII. It is one of my favorite episodes. "The Woman" forever changed SHERLOCK.