NEWARK, NJ, USA
N99838
AEROSPATIALE ATR42-300
FLIGHT 3444 ENCOUNTERED SEVERE TURBULENCE AND ICING CONDITIONS WHILE ON APPROACH TO RUNWAY 4R AT NEWARK INTERNATIONAL AIRPORT. AN ANALYSIS OF THE WEATHER REVEALED THAT THERE WERE 'STRONG HORIZONTAL GUSTS' AND SEVERE TURBULENCE IN THE NEWARK AREA BELOW 5,000 FEET. ALSO, THE FLIGHTCREW STATED THAT THEY HAD BEEN FLYING IN ICING CONDITIONS THAT CONSISTED OF A MIXTURE OF RIME AND CLEAR ICE. THE CAPTAIN STATED THAT HE OBSERVED ABOUT 3 INCHES OF ICE ON TOP OF THE WING, BEHIND THE LEADING EDGE WING BOOT. APPROVED PROCEDURES FOR FLIGHT IN ICING CONDITIONS REQUIRE THE PROPELLER SPEED BE MAINTAINED AT 86 PERCENT OR HIGHER TO PREVENT UNEVEN ICE ACCUMULATION OF THE WING. THE DFDR INFORMATION REVEALED THE CREW HAD THE PROPELLER SPEED AT 77 PERCENT, 9 PERCENT THE REQUIRED MINIMUM.
ON MARCH 4, 1993, AT 1704 EASTERN STANDARD TIME , AN AEROSPATIALE ATR-42-300, N99838, REGISTERED TO BRITT AIRWAYS AND OPERATING AS CONTINENTAL EXPRESS FLIGHT 3444, EXPERIENCED AN IN-FLIGHT UPSET WHILE ON APPROACH TO NEWARK INTERNATIONAL AIRPORT, NEWARK, NEW JERSEY. THE UPSET OCCURRED WHILE THE AIRPLANE WAS FLYING IN REPORTED "SEVERE" TURBULENCE AND ICING CONDITIONS. THE FLIGHTCREW STATED THAT THEY ENCOUNTERED ICING CONDITIONS WHILE DESCENDING OVER YARDLEY INTERSECTION, ON THE APPROACH TO RUNWAY 4R AT NEWARK. THE FLIGHTCREW STATED THAT AIRFRAME ICE WAS BEING SHED FROM THE PROTECTED AREAS, BUT THEY ALSO NOTED THAT THERE WAS AN ACCUMULATION OF ICE ON TOP OF THE WING, AFT OF THE LEADING EDGE BOOT. THE CREW ALSO STATED THAT THEY HAD BEEN IN THE ICING CONDITIONS FOR APPROXIMATELY 10 TO 15 MINUTES. THE CREW DESCRIBED THE ENVIRONMENTAL CONDITIONS AS CLOUDS TOPS BEING AT 10,000 TO 11,000 FEET, THE TEMPERATURE WAS ABOVE FREEZING AT ABOUT 3,000 FEET, HOWEVER, THEY WERE FLYING IN FREEZING RAIN CONDITIONS WHILE BEING VECTORED. THE ALTITUDES WHERE ICING CONDITIONS HAD BEEN ENCOUNTERED WERE BETWEEN 5,000 AND 11,000 FEET. THE CAPTAIN DESCRIBED THE ICING CONDITIONS AS LIGHT TO OCCASIONAL MODERATE, AND THAT THERE WAS MIXED RIME AND CLEAR ICE. HE STATED THAT THE ICE ACCUMULATED TO ABOUT 3 INCHES AFT OF THE PROTECTED SURFACES, AND AS FAR AFT AS HE COULD SEE. THE ICE WAS OBSERVED TO BE ONLY ON TOP OF THE WING. IN ADDITION, THERE WAS MODERATE TURBULENCE IN THE ICING ENVIRONMENT, INCLUDING WINDSHEAR OF ABOUT 10 KNOTS. THE DFDR REVEALED THAT WHILE THE AIRPLANE WAS ON APPROACH, THE AUTOPILOT HAD DISCONNECTED AND THE AIRPLANE ROLL ABOUT 48 DEGREES, RIGHT WING DOWN, WHILE AT A SPEED OF 168 KNOTS. THE INITIAL ROLL EXCURSION WAS FOLLOWED BY SEVERAL MORE THAT WERE RECORDED TO BE BETWEEN 22 AND 27 DEGREES RIGHT WING DOWN. THE LAST ROLL EVENT OCCURRING AT 190 KNOTS. FURTHER INVESTIGATION OF THE FLIGHTCREW'S OPERATION OF THE AIRPLANE, AND INFORMATION REVEALED ON THE DFDR INDICATE THAT THE CREW HAD THE PROPELLER SPEED AT 77 PERCENT DURING THE FLIGHT IN ICING CONDITIONS. ACCORDING TO CONTINENTAL EXPRESS AND ATR, THE PROCEDURES FOR OPERATING IN ICING CONDITIONS REQUIRE THE PROPELLER SPEED TO BE AT 86 PERCENT OR HIGHER TO REDUCE THE POSSIBILITY OF UNEVEN ICE ACCRETIONS ON 100 PERCENT OF THE AERODYNAMIC CHORD OF THE WING. FURTHER EXAMINATION OF THE WEATHER REVEALED THAT "SEVERE TURBULENCE AND STRONG HORIZONTAL GUSTS" OCCURRED IN THE NEWARK AREA BELOW 5,000 FEET.
THE FLIGHTCREW'S FAILURE TO FOLLOW APPROVED PROCEDURES THAT REQUIRED A MINIMUM PROPELLER SPPED WHILE FLYING IN ICING CONDITION. CONTRIBUTING TO THE LOSS OF ROLL CONTROL WERE THE ENCOUNTERS WITH SEVERE TURBULENCE AND ICING CONDITIONS.
Source: NTSB Aviation Accident Database
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