The pilot of a crop-dusting plane probably did not see a meteorological tower before he crashed into it and died in Contra Costa County last year, and more such accidents are possible unless such towers are better marked, federal investigators have concluded.
Stephen Allen, 58, of Courtland (Sacramento County) died when his S-2R Thrush Commander crashed into the tower on Webb Tract Island the morning of Jan. 10, 2011. The island is in the Sacramento-San Joaquin River Delta northeast of the Antioch Bridge.
Allen was applying seed at the time and probably didn't know the tower was there, said a report issued last week by the National Transportation Safety Board. The tower was 198 feet tall, just two feet shorter than the height that would require it to be marked and lighted under Federal Aviation Administration regulations, the board said.
The tower on Webb Tract Island was erected in April 2009, the report said. "The pilot likely had limited opportunity to become aware of the (tower) before the flight, and his ability to detect it visually in flight was extremely limited," the report said.
The Federal Aviation Administration issued recommendations last year on marking meteorological towers, including painting towers white and a bright color known as "aviation orange."
However, the agency said it would be impractical to recommend that towers be illuminated because the remoteness of many towers "does not allow for pre-existing power sources."
The agency's suggestions are only advisory, the safety board noted, and the structures "will likely continue to meet only the minimum requirements and, thus, will remain a hazard to pilots operating at low altitudes."
Source: http://www.sfgate.com
NTSB Identification: WPR11LA094
14 CFR Part 137: Agricultural
Accident occurred Monday, January 10, 2011 in Oakley, CA
Probable Cause Approval Date: 01/17/2012
Aircraft: ROCKWELL INTERNATIONAL S-2R, registration: N4977X
Injuries: 1 Fatal.
The pilot was initiating an aerial application to a field when the airplane collided with a 198-foot-tall, unpainted metal meteorological evaluation tower (MET). No information about the MET was distributed in any Federal Aviation Administration (FAA) notices or other publications for pilots, and the MET was not equipped with any markings or obstruction lights for visual conspicuity. For these reasons, the pilot likely had limited opportunity to become aware of the MET before the flight, and his ability to detect it visually in flight was extremely limited. Although the pilot’s toxicological results were positive for dextromethorphan (an over-the-counter cough suppressant) and dextrorphan (a metabolite of dextromethorphan) in the urine, the substances were not noted in the blood; therefore, it is likely that some time had passed since the pilot had used the medication. Additionally, these substances would not normally be expected to result in any impairment.
METs are used to measure wind data throughout the United States. They can be assembled quickly and can be constructed of galvanized tubing with guy wires used as support. Because many METs (like the accident MET) are just below the 200-foot threshold at which FAA regulations would require the applicant to notify the FAA of the MET and to provide a lighting and marking plan for FAA assessment, many METs are unmarked, unlighted, and not referenced in any FAA notices or publications for pilots. Although the FAA in 2011 approved an update to Advisory Circular (AC) 70/7460-1K, Obstruction Marking and Lighting, that will provide recommended guidance on marking METs, ACs are only advisory in nature. Because of this, MET constructions will likely continue to meet only the minimum requirements and, thus, will remain a hazard to pilots operating at low altitudes. In March 2011, the NTSB published Safety Alert SA-016 to educate pilots about the flight-safety issues presented by METs. The Safety Alert is available at the NTSB’s website at http://www.ntsb.gov/safety/safety_alerts.html.
The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
An in-flight collision with an unmarked meteorological evaluation tower (MET) during an aerial application flight due to the pilot's failure to see and avoid the obstacle. Contributing to the accident was the lack of visual conspicuity of the MET and the lack of information available to the pilot about the MET before the flight.
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