NTSB Identification: FTW94FA102B
Accident occurred Saturday, March 19, 1994 in SAN ANTONIO, TX
Probable Cause Approval Date: 12/07/1994
Aircraft: INTERSTATE S-1B1, registration: N46951
Injuries: 4 Fatal.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

THREE AIRPLANES, A TAYLORCRAFT (L-2), AN INTERSTATE (L-6), AND A PIPER (L-3) WERE FLYING A PHOTOGRAPHIC FORMATION FLIGHT THAT WAS PLANNED AND BRIEFED. THE BRIEF CALLED FOR THE L-6 TO LEAD THE FLIGHT WITH THE L-2 FLYING IN THE LEFT WING POSITION AND THE L-3 IN RIGHT WING FORMATION WITH ABOUT A TWO WING SPAN SEPARATION. THERE WAS NO PLAN FOR ANY SIGNALS BETWEEN PILOTS. A PHOTOGRAPHER IN THE L-6 WAS TO TAKE PICTURES OF THE L-3, WITH THE CITY IN THE BACKGROUND. THE FORMATION HAD EXECUTED TWO LEFT HAND ORBITS, WITH THE L-2 INSIDE THE TURNS, WHEN THE LEAD AIRPLANE INITIATED ANOTHER LEFT TURN. DURING THAT TURN, THE L-2 COLLIDED WITH THE L-6. THE THIRD AIRPLANE WAS NOT INVOLVED. THE LEFT WING SEPARATED FROM THE L-6 AND THE EMPENNAGE OF THE L-2 WAS DAMAGED. FOLLOWING THE COLLISION BOTH AIRPLANES WENT OUT OF CONTROL AND IMPACTED THE GROUND.

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

THE FAILURE OF THE PILOT OF THE OTHER AIRCRAFT TO MAINTAIN ADEQUATE CLEARANCE DURING FORMATION FLIGHT. A FACTOR WAS THE PILOT'S INADEQUATE PREFLIGHT PLANNING AND PREPARATION REGARDING INFLIGHT FORMATION PROCEDURES.

Full narrative available

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