ACCORDING TO WITNESSES, THE PILOT ATTEMPTED A FORMATION TAKEOFF WITH ANOTHER AIRCRAFT. BOTH AIRPLANES WERE OBSERVED TO BEGIN THE TAKEOFF ROLL AND LIFT OFF FROM THE SAME RUNWAY AT THE SAME TIME. DURING THE TAKEOFF ROLL, THE PILOT OF THE ACCIDENT AIRPLANE PREMATURELY LIFTED OFF AT AN AIRSPEED THAT WAS NOT ADEQUATE TO SUSTAIN FLIGHT. THE AIRPLANE AERODYNAMICALLY STALLED ABOUT 50 FEET ABOVE THE RUNWAY. IT IMPACTED SNOW-COVERED TERRAIN OFF THE EDGE OF THE RUNWAY AND WAS SUBSTANTIALLY DAMAGED. NO PREIMPACT MECHANICAL DEFICIENCIES WERE REPORTED.