NTSB Identification: DCA84AA025.
The docket is stored on NTSB microfiche number 26503.
Scheduled 14 CFR UNITED AIRLINES
Accident occurred Thursday, May 31, 1984 in DENVER, CO
Probable Cause Approval Date: 08/30/1994
Aircraft: BOEING 727-222, registration: N7640U
Injuries: 105 Uninjured.

BEFORE TAKEOFF, THE CREW OF N7647U (UA FLT 663) NOTED CUMULUS CLOUDS & VIRGA IN THE AREA. AT 1327, A DEHAVILLAND DASH 7 CREW RPRTD A 25 KT LOSS OF AIRSPEED, BUT SVRL OTHER ACFT THEN TOOK OFF WITHOUT RPRTG A PROBLEM. DUE TO RADIO CONJESTION,THE CAPTAIN DID NOT QUERY OTHER AIRCREWS, BUT DECIDED TO CLIMB OUT AT V2 PLUS 20. WHEN THE CONTROLLER CLEARED FLT 663 FOR TAKEOFF, HE ADVISED THE CREW OF NUMEROUS WIND SHEARS IN 3 QUADRANTS, BUT USED INCORRECT TERMINOLOGY IN ISSUING THE WIND SHEAR ALERT. DURING TAKEOFF, THE ACFT STRUCK AN ILS LOCALIZER ANTENNA, 1074 FT FROM THE DEPT END OF THE RWY, & DAMAGED THE LOWER FUSELAGE. WHEN UNABLE TO PRESSURIZE THE ACFT, THE CREW RETURNED TO THE ARPT & LANDED. AN INVESTIGATIONREVEALED THE ACFT ENCOUNTERED WIND SHEAR FROM MICROBURST ACTIVITY WHICH REACHED ITS GREATEST ACTIVITY AS FLT 663 WAS TAKING OFF. THE WIND SHEARED FROM AN 8 KT HEADWIND TO 40 TO 56 KTS OVER A 44 SEC PERIOD. THE CREW NOTED A HESITATION WHILE ACCELERATING THRU 120 KTS, THEN AT OR BEYOND VR SPEED OF APRX 141 KTS, THE ACFT MOMENTARILY LOST 20 KTS.

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

WEATHER CONDITION..WINDSHEAR


Contributing Factors

OBJECT..APPROACH LIGHT/NAVAID


Contributing Factors

WEATHER CONDITION..RAIN


Contributing Factors

WEATHER CONDITION..HIGH WIND


Contributing Factors

WEATHER CONDITION..GUSTS


Contributing Factors

WEATHER CONDITION..UNFAVORABLE WIND



Contributing Factors

RADIO COMMUNICATIONS..EXCESSIVE


Contributing Factors

AIRPORT/FACILITIES..INADEQUATE


Contributing Factors

WEATHER EVALUATION..INACCURATE..PILOT IN COMMAND


Contributing Factors

INFORMATION UNCLEAR..ATC PERSONNEL(LCL/GND/CLNC)

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