ARDMORE, OK, USA
N9448B
CESSNA 208B
STRUCTURAL ICE ACCUMULATED ON THE AIRPLANE AT A RAPID RATE WHILE THE PILOT WAS EXECUTING A PROCEDURE TURN DURING AN NDB APPROACH TO HIS DESTINATION AIRPORT. THE PILOT APPLIED MAXIMUM AVAILABLE POWER BUT WAS UNABLE TO ARREST THE RATE OF DESCENT. THE PILOT MAINTAINED 110 KNOTS DURING THE APPROACH AND AFTER BREAKING OUT INTO VISUAL CONDITIONS ELECTED TO PERFORM A FORCED LANDING IN AN OPEN FIELD 2 MILES SHORT OF THE DESTINATION AIRPORT. THE PILOT WAS UNABLE TO ARREST HIS DESCENT AND THE AIRPLANE IMPACTED THE GROUND IN A 5 DEGREE NOSE DOWN ATTITUDE. THE PILOT ALSO STATED THAT HIS FORWARD VISIBILITY WAS COMPLETELY OBSCURED BY THE ACCUMULATION OF CLEAR ICE ON THE WINDSHIELD. THE AIRPORT MANAGER INFORMED THE PILOT THAT FREEZING DRIZZLE WAS PRESENT AT THE AIRPORT WHEN THE PILOT CALLED THE UNICOM DURING THE INITIAL PORTION OF THE INSTRUMENT APPROACH.
HISTORY OF FLIGHT On March 2, 1995, at 0815 central standard time, a Cessna 208B, N9448B, was substantially damaged during a forced landing near Ardmore, Oklahoma. The instrument rated commercial pilot suffered minor injuries. The airplane, operating under the callsign Martinaire 633, was owned by Cessna Finance Corporation, of Wichita, Kansas, and operated by MartinAire of Dallas, Texas. Instrument meteorological conditions prevailed for the 14 CFR Part 135 cargo flight. According to the operator, the airplane departed the Tulsa International Airport (TUL), at 0715 with a payload of 1,300 pounds of cargo, destined for the Ardmore Downtown Executive Airport (1F0). A weather briefing was received and an instrument flight plan filed. The pilot stated he was cleared for the NDB Runway 35 Approach to Ardmore while level at 5,000 feet. The pilot further stated that as he proceeded from the VOR to the NDB for the procedure turn, the airplane accumulated ice at a rapid rate. The pilot stated that he added maximum available power, as he continued to cycle the wing/strut deicing boots. The pilot stated that the airplane was configured with flaps up, airspeed at 110 knots when he broke out into visual conditions at approximately 400 feet AGL. The pilot further stated that he was unable to arrest the 400 to 500 fpm rate of descent to hold altitude. The airplane impacted in an open pasture in a nose low attitude. The nose landing gear separated, the mains collapsed, and the cargo pod was crushed. PERSONNEL INFORMATION The pilot who is home-based at Tulsa, Oklahoma, stated that he had been on duty since 2130 the previous night, and had flown a total of 4.2 hours during the same duty period. His last training session and check ride were completed on February 24, 1995. AIRCRAFT INFORMATION The 1988 model airplane was issued a normal category airworthiness certificate on September 22, 1988. The airplane was certified as a single pilot aircraft, certified for flights into known light to moderate icing conditions. The airplane was not equipped with deicing boots for the nosecap of the cargo pod or the landing gear struts. A review of the airframe and engine records by the FAA inspector, did not reveal any anomalies, uncorrected maintenance, or overdue airworthiness directives. All of the aircraft's deicing and anti-icing systems were reported as operational prior to the flight. The pilot had not reported any maintenance anomalies prior to the flight; however, during a post-accident interview the pilot stated that forward visibility through the detachable electric windshield anti-ice panel was inadequate, and his forward visibility was completely obscured by the accumulation of clear ice on the windshield. A review of the loading of the airplane revealed that at the time of the accident, the airplane was being operated within the prescribed weight and balance limits. METEOROLOGICAL INFORMATION The Automatic Weather Observation System (AWOS) weather report for Ardmore for 0700 CST was reported as sky partially obscured, 700 overcast, with a mile and a half visibility in drizzle. Temperature was 26 degrees, with a dew point of 25 degrees. The weather minimums for the NDB Runway 35 approach were 638 feet and 1 mile visibility. COMMUNICATIONS The pilot informed the airport manager on the Unicom frequency, that he had the current AWOS weather, and he was executing the NDB Runway 35 approach. The airport manager stated that he informed the pilot that freezing drizzle was present and the pilot acknowledged the transmission. His last radio transmission occurred when the pilot reported "procedure turn inbound" to the Unicom. WRECKAGE AND IMPACT INFORMATION The airplane impacted on an open pasture approximately 2 miles south of the approach end of runway 35, and one mile west of the extended centerline. Ground scars were found at the initial point of impact on a measured heading of 155 degrees. Chunks of rime and mixed ice contoured to the shape of several parts of the aircraft were found at the initial point of impact. The nose wheel strut and several other components associated with the nose wheel were found within 20 feet of the initial point of impact. After sliding for approximately 100 yards, the airplane came to rest on a measured magnetic heading of 330 degrees. All three composite blades separated at the hub. The spinner and hub assembly remained attached to the propeller shaft. The two main landing gears were found pushed aft and up, touching the respective wing strut. The belly cargo pod was crushed up and to the left. The wing flaps were found extended to 20 degrees. The elevator trim was found in the full nose up position. The engine inertial separator was found in the bypass mode. ADDITIONAL DATA The wreckage was released to the owner's representative on March 2, 1995, following completion of the field portion of the investigation. A teardown of the propeller was performed at the propeller manufacturer's facility. A copy of the examination report is enclosed.
THE PILOT'S CONTINUED FLIGHT INTO ADVERSE WEATHER CONDITIONS. FACTORS WERE THE ICING CONDITIONS PREVAILING AT THE DESTINATION AIRPORT, AND THE PILOT'S INABILITY TO MAINTAIN VISUAL LOOKOUT DUE TO WINDSHIELD ICING.
Source: NTSB Aviation Accident Database
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