From: Subject: LAX94FA383A Date: Mon, 10 Nov 2008 00:38:53 +0100 MIME-Version: 1.0 Content-Type: multipart/related; type="text/html"; boundary="----=_NextPart_000_001C_01C942CC.B5343930" X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 This is a multi-part message in MIME format. ------=_NextPart_000_001C_01C942CC.B5343930 Content-Type: text/html; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable Content-Location: http://www.ntsb.gov/ntsb/brief.asp?ev_id=20001206X02276&key=1 LAX94FA383A
NTSB Identification: LAX94FA383A
Accident occurred = Tuesday,=20 September 27, 1994 in MESA, AZ
Probable Cause Approval Date:=20 1/19/1996
Aircraft: MCDONNELL DOUGLAS 520N, registration: = N520NT
Injuries:=20 1 Fatal, 1 Serious, 2 Uninjured.

A TEST HELICOPTER (MCDONNELL DOUGLAS AH-64D, WITH 1 VHF RADIO) AND A = CHASE=20 HELICOPTER (MCDONNELL DOUGLAS 520N, WITH 2 VHF RADIOS) WERE ON A NIGHT = VFR=20 FLIGHT FROM CHANDLER, AZ, TO THE MCDONNELL DOUGLAS HELIPORT AT MESA, AZ. = THE=20 MISSION OF THE CHASE CREW (CHASE) WAS TO SURVEIL THE AREA FOR THE TEST = CREW=20 (LEAD) AND TO PROVIDE INFORMATION CONCERNING OTHER AIR TRAFFIC OR = HAZARDS. THE=20 DESTINATION HELIPORT WAS LOCATED JUST NORTH OF FALCON FIELD. DURING = ARRIVAL,=20 LEAD NOTIFIED CHASE OF A VHF FREQUENCY CHANGE TO THE FALCON FIELD TOWER = (ATCT)=20 FREQUENCY. CHASE ACKNOWLEDGED; THIS WAS THE LAST KNOWN TRANSMISSION FROM = CHASE.=20 LEAD THEN CHANGED TO THE HELIPORT'S 'APACHE RAMP CONTROL' FREQUENCY. THE = GROUND=20 CONTROL RADIO OPERATOR, MONITORING THE FREQUENCY, CLEARED THE = HELICOPTER(S) TO=20 LAND ON RUNWAY 22 AT THE HELIPORT. SOON THEREAFTER, THE CHASE HELICOPTER = COLLIDED WITH THE LEAD HELICOPTER. DURING THE MIDAIR COLLISION, THE MAIN = ROTOR=20 BLADES OF CHASE STRUCK THE LEFT WING AND WING STORES OF LEAD. LEAD = CONTINUED TO=20 A SAFE LANDING, BUT THE MAIN ROTOR SEPARATED FROM THE CHASE HELICOPTER, = AND IT=20 CRASHED. AN INVESTIGATION REVEALED THE CHASE HELICOPTER HAD CONVERGED ON = THE=20 LEAD HELICOPTER FROM THE LEFT REAR QUADRANT. AN EXPLETIVE OF AN UNKNOWN = SOURCE=20 WAS TRANSMITTED ON THE ATCT FREQUENCY AT ABOUT THE TIME OF THE MIDAIR = COLLISION.=20 TESTS OF THE RADIOS FROM THE CHASE HELICOPTER REVEALED THEY WERE BOTH ON = THE=20 ATCT FREQUENCY.=20

The National Transportation Safety Board determines the probable = cause(s) of=20 this accident as follows:

FAILURE OF THE CHASE HELICOPTER PILOT TO = MAINTAIN=20 CLEARANCE FROM THE LEAD HELICOPTER DURING A NIGHT APPROACH TO LAND. = POSSIBLE=20 FACTORS RELATING TO THE ACCIDENT WERE: DARKNESS, AND INADEQUATE RADIO=20 COORDINATION BETWEEN FLIGHT CREWS OF THE TWO HELICOPTERS.=20

Full=20 narrative available

I= ndex=20 for Sep1994 | Index = of=20 months

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