Have a read of this, and tell me what you think the improper activity was.

THE PRIVATE PILOT AND A PILOT RATED PASSENGER WERE GOING TO PRACTICE SIMULATED INSTRUMENT FLIGHT. WITNESSES OBSERVED THE AIRPLANE'S RIGHT WING FAIL IN A DIVE AND CRASH. EXAMINATION OF THE WRECKAGE AND BODIES REVEALED THAT BOTH OCCUPANTS WERE PARTIALLY CLOTHED AND THE FRONT RIGHT SEAT WAS IN THE FULL AFT RECLINING POSITION. NEITHER BODY SHOWED EVIDENCE OF SEATBELTS OR SHOULDER HARNESSES BEING WORN. EXAMINATION OF THE INDIVIDUALS' CLOTHING REVEALED NO EVIDENCE OF RIPPING OR DISTRESS TO THE ZIPPERS AND BELTS.

The National Transportation Safety Board determines the probable cause(s) of this accident as follows:

THE PILOT IN COMMAND'S IMPROPER INFLIGHT DECISION TO DIVERT HER ATTENTION TO OTHER ACTIVITIES NOT RELATED TO THE CONDUCT OF THE FLIGHT. CONTRIBUTING TO THE ACCIDENT WAS THE EXCEEDING OF THE DESIGN LIMITS OF THE AIRPLANE LEADING TO A WING FAILURE

Moral - if you want to join the mile high club, make sure you aren't the PILOT!

*nods to http://kristopherjohnson.blogspot.com/