NTSB Identification: LAX03FA069.
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Accident occurred Wednesday, January 08, 2003 in FLAGSTAFF, AZ
Probable Cause Approval Date: 09/13/2005
Aircraft: Piper PA-23-250, registration: N135LA
Injuries: 4 Fatal.
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.
The airplane collided with trees and mountainous terrain after encountering adverse weather conditions, including clouds, rain, and moderate rime icing. The airplane was on a cross-country flight across northern Arizona and was receiving VFR flight advisories from Albuquerque Air Route Traffic Control Center (ARTCC). While en route near Flagstaff at 11,500 feet mean sea level (msl), the pilot advised the controller that he was unable to maintain visual flight due to clouds, rain, and ice, and requested an IFR clearance into Flagstaff. Review of the recorded air-to-ground communications tapes disclosed that the transmission from the airplane was scratchy and of poor quality. The investigation later determined that on the morning of the accident, an underground fiber optic communication line was cut, which disrupted the quality of air-to-ground and ground-to-air communications in northern Arizona, causing broken and garbled services. Landline communications were also affected, which required a nearby Flight Service Station to relay land line messages between the tower and the ARTCC. The controller advised the pilot of rime ice reports at 13,000 feet on his course, and the pilot responded that his altitude was 12,000 feet and he was accumulating some ice. The controller advised the pilot of the airport's location. The pilot's reply was broken and unreadable. The controller asked the pilot if he had the airport in sight, and the pilot responded that no he was in some clouds. The pilot then requested to go to the tower frequency and land, and the controller issued a VFR transponder code and handed the flight off to the tower. About 2 minutes later the pilot reported back to the controller and advised that he was unable to get a visual on the ground and would like to get an IFR clearance into the airport. The controller advised the pilot to climb to 11,000 feet. and enter the published holding pattern southeast of the FLG VOR on the 113-degree radial. The pilot acknowledged the clearance and this was the last communications received from the aircraft. The wreckage was located 10 miles north of the VOR at 8,900 feet msl. Impact signatures and ground scars showed the aircraft collided with mature pine trees in a near wings level attitude while in a shallow descent. A post crash fire destroyed the cockpit, including the navigation radios and related instrumentation. On December 6, 2002, the Flagstaff visual omni range (VOR) navigational aid frequency was changed from 108.2, to 113.85. A partially burned Phoenix sectional chart dated November 1, 2001, was recovered from the wreckage that listed 108.2 as the VOR frequency. No other navigational reference material was recovered from the burned wreckage.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: the pilot's failure to comply with his instrument clearance route instruction and to maintain his assigned altitude. A factor in the accident was the poor quality of radio communications due to the severance of underground fiber optic voice and data lines for the ARTCC, which also affected inter and intra facility landline communications. Full narrative available
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