History of Flight
On January 10, 2011, at 1057 Pacific standard time, a Rockwell International S-2R, registration N4977X, 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, who was the sole occupant, was fatally injured. Alexander Ag Flying Service Incorporated was operating the airplane under 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 who 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, after which the airplane impacted the 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 stated that the MET was erected in April 2009. Contra Costa County personnel who approved the construction noted that the permit was granted in August 2008 and was applicable until August 2009. No extension on the permit was issued.
Tower Description
The project description stated that the tower stood 197 feet 8.25 inches tall and was designed specifically for wind resource measurements. It also stated, "The 60-meter (197 feet) tower is lower than the 200 feet threshold set by the FAA, and as such meets FAA regulations."
Pilot Information
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. He reported 26,000 total flight hours on his last medical application.
Medical Information
An autopsy performed on January 11, 2011, by the Office of the Sheriff-Contra Costa County Coroner's Division attributed the cause of death to trauma sustained in the accident. Forensic toxicology performed by the FAA Bioaeronautical Sciences Research Laboratory was negative for carbon monoxide, cyanide, and ethanol. The toxicology report indicated that dextromethorphan, dextrorphan, and ibuprofen were detected in urine, but 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, "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."
A review of accident data involving aircraft colliding with METs showed two other fatal accidents: one in 2005 in Ralls, Texas (NTSB accident number: DFW05LA126) and another in 2003 in Vansycle, Oregon (NTSB accident number: SEA04LA027).
State and FAA Actions
Prior to FAA action, numerous states took action to mandate requirements for METs at the local level. Examples 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.
Title 14 CFR Part 77.13 states that notice to the FAA is required for any construction or alteration of more than 200 feet in height above ground level. In January 2011, the FAA issued a notice of proposed rulemaking to update Advisory Circular (AC) 70/7460-1K to recommend the marking of METs. In June 2011, the FAA approved the recommended guidance for voluntary marking of METs. Advisory circulars are advisory and not regulatory. Regional FAA FAAST teams have been educating operators about the dangers of METs through presentations and distribution of brochures.