On January 10, 2011, at 1057 Pacific standard time, N4977X, a Rockwell International S-2R, impacted a meteorological evaluation tower (MET) while initiating an aerial application on Webb Tract Island, Oakley, California. The airplane sustained substantial damage. The commercial pilot was fatally injured. Alexander Ag Flying Service Incorporated was operating the airplane under the provisions of Title 14 Code of Federal Regulations Part 137. Visual meteorological conditions prevailed, and no flight plan was filed.

According to the Federal Aviation Administration inspector that responded to the accident site, the pilot was conducting an aerial application when the accident occurred. Witnesses indicated that the pilot overflew the area and then began the first pass over the field. The airplane then impacted a MET. Witnesses did not report seeing the airplane perform any evasive maneuvers prior to the impact. The tower was unpainted metal, and was not equipped with obstruction lights or markings.

The land owner indicated that the MET on Webb Tract Island was erected in April 2009. According to Contra Costa Country personnel that approved the construction of the MET, the permit was approved in August 2008, and applicable until August 2009. There was no extension on the permit.

The project description stated that the tower stood 197 feet 8.25 inches tall, and was designed specifically for wind resource measurements. Additionally, it stated "The 60-meter (197 feet) tower is lower than the 200 feet threshold set by the FAA, and as such meets FAA regulations."


The pilot, age 58, held a commercial pilot certificate for airplane single and multi-engine land with an instrument rating. He held a second-class airman medical certificate issued on October 13, 2010, with no limitations. The pilot reported 26,000 total flight hours on his last medical application.


An autopsy was performed on the pilot on January 11, 2011, by the Office of the Sheriff- Contra Costa County Coroner's Division. The autopsy attributed the cause of death to trauma sustained in the aircraft accident.

Forensic toxicology was performed on specimens from the pilot by the FAA Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma. The toxicology report was negative for carbon monoxide, cyanide, and ethanol. The toxicology report indicated that dextromethorphan, dextrorphan, and ibuprofen were detected in urine. The dextromethorphan and dextrorphan were not detected in blood.


Meteorological Evaluation Towers (METs)

METs are used nationwide to measure wind data. According to a National Agricultural Aviation Association article on METs, "Met testing towers are used for gathering wind data during the development and siting of wind energy conversion facilities. The met towers consist of galvanized tubing assembled at the site, and raised and supported using guy wires. Agricultural pilots, emergency medical services (EMS) operations, Fish and Wildlife, animal damage control, aerial fire suppression, and any other low-level flying operation may be affected. The fact that these towers are narrow, unmarked, and grey in color makes for a structure that is nearly invisible under some atmospheric conditions."

Review of accident data involving aircraft colliding with METs showed that in addition to this accident, two other fatal accidents occurred. One was in 2005 in Ralls, Texas (NTSB accident number: DFW05LA126) and the other was in 2003 in Vansycle, Oregon (NTSB accident number: SEA04LA027).

State Actions

Prior to FAA action, numerous states took action to mandate requirements for METs at the local level. Examples of these actions include South Dakota requiring that METs be marked, and Wyoming maintaining an online database of METS and requiring all METs to be registered and marked so that they are visible from a distance of 2,000 feet. State and national industry groups also worked with the FAA on recognition of the hazards posed by METs to aircraft operating at low altitudes.

FAA Guidance on METs

Title 14 CFR Part 77.13 "Construction or alteration requiring notice" states "(a) Except as provided in 77.15, each sponsor who proposes any of the following construction or alteration shall notify the Administrator in the form and manner prescribed in 77.17: (1) Any construction or alteration of more than 200 feet in height above the ground level at its site."

In January of 2011, the FAA issued a notice of proposed rulemaking (docket number FAA-2010-1326) to update Advisory Circular (AC) 70/7460-1K, Obstruction Marking and Lighting, to recommend the marking of METs. In June of 2011, the FAA approved the recommended guidance for voluntary marking of METs to be provided in the update AC 70/7460-1K. ACs are advisory and not regulatory.

Regional FAA FAAST teams have been educating operators about the dangers of METs. This has been accomplished through presentations, as well as through distribution of brochures highlighting the issue.

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