History of Flight
On July 23, 2016, about 0745 Pacific daylight time, two Air Tractor AT-502Bs, N502WC and N5044N, collided in-flight near Zamora, California. N502WC was operated by Farm Air Flying Services, and N5044N was operated by Growers Air Service. Both flights were conducted under Title 14 Code of Federal Regulations Part 137 as aerial application flights. Visual meteorological conditions prevailed, and company flight plans had been filed for both flights.
The pilot of N502WC had finished spraying mosquito repellant and was traveling eastbound en route to Farm Air Flying Services. The pilot of N5044N had finished spraying a rice field and was traveling southbound en route to Growers Air Service.
During a postaccident interview, the pilot of N5044N reported that he could not recall his altitude but stated that it would normally have been at least 500 ft above ground level. He added that he observed N502WC on his right side traveling toward him when he maneuvered his airplane and ascended; however, N502WC contacted the undercarriage of his airplane and subsequently collided with terrain. The pilot of N5044N was unable to maintain altitude and subsequently performed a forced landing to an open field. According to the pilot of N5044N, the pilot of N502WC would have been traveling toward the sun and likely did not see him before the collision.
Personnel Information
The pilot of N502WC, age 25, held a commercial pilot certificate with a rating for airplane single engine land. He also held a mechanic certificate with airframe and powerplant ratings. His most recent second-class FAA medical certificate was issued on March 30, 2016, with no limitations. On the application, he reported 2,250 total hours of flight experience, with 450 hours in the previous 6 months. According to his logbook, the most recent flight review was performed on February 16, 2016.
The pilot of N5044N, age 64, held a commercial pilot certificate with ratings for airplane single-engine land and instrument airplane. His most recent FAA second-class medical certificate was issued on October 1, 2015, with the limitation to wear corrective lenses. He had been flying for Growers Air Services for the past 27 years. His flight experience was not determined.
Aircraft Information
Both airplanes were painted yellow with blue trim. N502WC, serial number 502B-2830, was manufactured in 2012 and equipped with a 750-shaft horsepower Pratt & Whitney Canada PT6A-34AG engine. The most recent annual inspection was completed on May 1, 2016, at an airframe total time of 967.5 hours. N5044N, serial number 502B-0452, was manufactured in 1997 and equipped with the same engine model. The airplane Hobbs hour meter indicated 1,533.8 hours' time-in-service. The airplane logbooks were not made available for review.
Meteorological Information
According to the sun position chart, sunrise was at 0600. The sun's azimuth at 0745 was 64°, at an elevation of 18° above the horizon.
Wreckage and Impact Information
The accident sites were separated by about 2/3 mile. N502WC came to rest partially intact in an organic rice field on a magnetic heading of 280°. The vertical stabilizer and rudder separated from the empennage and were not located. The propeller hub with blades separated and was located near the main wreckage. The top portion of the nose and cockpit canopy separated. The main landing gear remained attached. The airplane was equipped with an AmSafe inflatable restraint system, which deployed. N5044N landed upright in a plowed open field. The airplane remained intact except for the landing gear and spray equipment, which separated. Both wings remained attached; the left wing sustained damage the length of the wing, and the aileron was damaged. The wing tip had blue paint transfer on the underneath portion. The airplane came to rest on a 100° magnetic heading. Flight control continuity was established from the cockpit to all flight controls surfaces. The AmSafe inflatable restraint system had not deployed. Neither airplane exhibited any mechanical malfunctions or anomalies that would have precluded normal operation.
Medical and Pathological Information
A postmortem examination of the pilot of N502WC was performed by the County of Sacramento Department of Coroner. The cause of death was reported as multiple injuries. Forensic toxicology testing identified hydrocodone at 46 ng/ml (0.046 ug/ml) and its metabolite dihydrocodeine at 10 ng/ml (0.010 ug/ml) in femoral blood. Two sedating antihistamines, chlorpheniramine and diphenhydramine, were found in subclavian and heart blood respectively, at levels below the calibration curve and below the lower end of therapeutic ranges. Sertraline and its metabolite were found in liver and lung tissue. Tramadol and its metabolite were found in urine but not in blood. Loose white oblong tablets with imprint "M367" (acetaminophen and hydrocodone) were recovered from the pilot's pants pocket. The pilot of N5044N received minor injuries and was transported to the hospital. He reported the use of simvastatin. No postaccident toxicology was performed on him.
Tests and Research
Two onboard devices were shipped to the NTSB Vehicle Recorder Division: a Hemisphere Satloc G-4 from N502WC and a Satloc M3 CPU from N5044N. The Satloc G-4 recorded data for the accident flight between 0624:48 and 0739:49 PDT. The data ended as the airplane was traveling eastbound about 143 mph. The last recorded log was at 0739:45.9 at an altitude of 433.9 ft agl and airspeed of 143.16 mph. The Satloc M3 CPU data contained only ground operations from 0531 and 0532 on the day of the accident.
Additional Information
The FAA Airplane Flying Handbook states that all pilots must be alert to the potential for midair collision and maintain vigilance at all times, regardless of flight rules. Most midair collisions occur in good VFR weather conditions during daylight hours, within 5 miles of an airport or near navigation aids. The NTSB released a Special Investigation Report on the Safety of Agricultural Aircraft Operations and two safety alerts addressing midair collisions: SA-045 and SA-058. The National Agricultural Aviation Association recommends ferrying above 500 ft agl and seeing and avoiding other aircraft.