NTSB Identification: LAX94FA383B
Accident occurred Tuesday, September 27, 1994 in MESA, AZ
Probable Cause Approval Date: 01/19/1996
Aircraft: MCDONNELL DOUGLAS AH-64D, registration: R0324
Injuries: 1 Fatal,1 Serious,2 Uninjured.

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.

A TEST HELICOPTER (MCDONNELL DOUGLAS AH-64D, WITH 1 VHF RADIO) AND A CHASE HELICOPTER (MCDONNELL DOUGLAS 520N, WITH 2 VHF RADIOS) WERE ON A NIGHT VFR FLIGHT FROM CHANDLER, AZ, TO THE MCDONNELL DOUGLAS HELIPORT AT MESA, AZ. THE MISSION OF THE CHASE CREW (CHASE) WAS TO SURVEIL THE AREA FOR THE TEST CREW (LEAD) AND TO PROVIDE INFORMATION CONCERNING OTHER AIR TRAFFIC OR HAZARDS. THE DESTINATION HELIPORT WAS LOCATED JUST NORTH OF FALCON FIELD. DURING ARRIVAL, LEAD NOTIFIED CHASE OF A VHF FREQUENCY CHANGE TO THE FALCON FIELD TOWER (ATCT) FREQUENCY. CHASE ACKNOWLEDGED; THIS WAS THE LAST KNOWN TRANSMISSION FROM CHASE. LEAD THEN CHANGED TO THE HELIPORT'S 'APACHE RAMP CONTROL' FREQUENCY. THE GROUND CONTROL RADIO OPERATOR, MONITORING THE FREQUENCY, CLEARED THE HELICOPTER(S) TO LAND ON RUNWAY 22 AT THE HELIPORT. SOON THEREAFTER, THE CHASE HELICOPTER COLLIDED WITH THE LEAD HELICOPTER. DURING THE MIDAIR COLLISION, THE MAIN ROTOR BLADES OF CHASE STRUCK THE LEFT WING AND WING STORES OF LEAD. LEAD CONTINUED TO A SAFE LANDING, BUT THE MAIN ROTOR SEPARATED FROM THE CHASE HELICOPTER, AND IT CRASHED. AN INVESTIGATION REVEALED THE CHASE HELICOPTER HAD CONVERGED ON THE LEAD HELICOPTER FROM THE LEFT REAR QUADRANT. AN EXPLETIVE OF AN UNKNOWN SOURCE WAS TRANSMITTED ON THE ATCT FREQUENCY AT ABOUT THE TIME OF THE MIDAIR COLLISION. TESTS OF THE RADIOS FROM THE CHASE HELICOPTER REVEALED THEY WERE BOTH ON THE ATCT FREQUENCY.

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

FAILURE OF THE CHASE HELICOPTER PILOT TO MAINTAIN CLEARANCE FROM THE LEAD HELICOPTER DURING A NIGHT APPROACH TO LAND. POSSIBLE FACTORS RELATING TO THE ACCIDENT WERE: DARKNESS, AND INADEQUATE RADIO COORDINATION BETWEEN FLIGHT CREWS OF THE TWO HELICOPTERS.

Full narrative available

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