NTSB Factual Report

HISTORY OF FLIGHT

On July 7, 2015, about 1101 eastern daylight time, a Cessna 150M, N3601V, and a Lockheed Martin F-16CM, operated by the US Air Force (USAF), collided in midair near Moncks Corner, South Carolina. The private pilot and passenger aboard the Cessna died, and the Cessna was destroyed during the collision. The damaged F-16 continued to fly for about 2 1/2 minutes, during which the pilot activated the airplane's ejection system. The F-16 pilot landed safely using a parachute and incurred minor injuries, and the F-16 was destroyed after its subsequent collision with terrain and postimpact fire. Visual meteorological conditions prevailed at the time of the accident. No flight plan was filed for the Cessna, which departed from Berkeley County Airport (MKS), Moncks Corner, South Carolina, about 1057, and was destined for Grand Strand Airport, North Myrtle Beach, South Carolina. The personal flight was conducted under the provisions of 14 Code of Federal Regulations (CFR) Part 91. The F-16 was operating on an instrument flight rules (IFR) flight plan and had departed from Shaw Air Force Base (SSC), Sumter, South Carolina, about 1020.

Air Force F-16

According to the USAF, the F-16 pilot was assigned as pilot-in-command for a single-ship, operational check flight to verify the completion of recent corrective maintenance. The flight itinerary included practice instrument approaches at Myrtle Beach International Airport (MYR), South Carolina, and Charleston Air Force Base/International Airport (CHS), Charleston, South Carolina, before returning to SSC. Since the flight was single ship and single pilot, the pilot performed an individual flight briefing using the personal briefing guide. (The Shaw General Briefing Guide is a local USAF document that F-16 pilots use to prepare for their missions.) Before departure, squadron personnel briefed the pilot on a range of subjects, including parking location, maintenance issues, aircraft configuration, notices to airmen, weather, and the mission timeline.

After departing from SSC, the F-16 proceeded to MYR, where the pilot conducted two practice instrument approaches before continuing to CHS. According to air traffic control (ATC) radar and voice communication data provided by the Federal Aviation Administration (FAA), the F-16 pilot contacted the approach controller at CHS about 1052 and requested to perform a practice tactical air navigation system (TACAN) instrument approach to runway 15. The controller instructed the F-16 pilot to fly a heading of 260º to intercept the final approach course. About 1055, the controller instructed the F-16 pilot to descend from 6,000 ft to 1,600 ft. About that time, the F-16 was located about 34 nautical miles (nm) northeast of CHS.

Cessna

Recorded airport surveillance video showed that the Cessna, which was based at MKS, departed from runway 23. At 1057:41, a radar target displaying a visual flight rules (VFR) transponder code of 1200, and later correlated to be the accident Cessna, appeared in the vicinity of the departure end of runway 23 at MKS at an indicated altitude of 200 ft. The Cessna continued its climb and began tracking generally southeast over the next 3 minutes. For the duration of the flight, the pilot of the Cessna did not contact any ATC facilities, nor was he required to do so.

The Collision

The CHS automated radar terminal system (ARTS IIE) detected a conflict between the F-16 and the Cessna at 1059:59. According to recorded radar data, the conflict alert (CA) was presented on the radar display and aurally alarmed at 1100:13, when the F-16 and the Cessna were separated laterally by 3.5 nm and vertically by 400 ft.

At 1100:16, the CHS approach controller issued a traffic advisory advising the F-16 pilot of "traffic 12 o'clock, 2 miles, opposite direction, 1,200 [ft altitude] indicated, type unknown." At 1100:24, the F-16 pilot responded that he was "looking" for the traffic. At 1100:26, the controller advised the F-16 pilot, "turn left heading 180 if you don't have that traffic in sight." At 1100:30, the pilot asked, "confirm 2 miles?" At 1100:33, the controller stated, "if you don't have that traffic in sight turn left heading 180 immediately." As the controller was stating the instruction and over the next 18 seconds, the radar-derived ground track of the F-16 began turning southerly toward the designated heading.

At 1100:49, the radar target of the F-16 was 1/2 nm northeast of the Cessna, at an altitude of 1,500 ft, and was on an approximate track of 215º. At that time, the Cessna reported an altitude of 1,400 ft and was established on an approximate ground track of 110º. At 1100:53, the controller advised the F-16 pilot, "traffic passing below you one thousand four hundred [ft]." At 1100:54, the altitude of the F-16 remained at 1,500 ft, and the last radar return was received from the Cessna. Recorded radar data indicated that the ARTS IIE continued to provide a CA to the controller until 1101:00. The next radar target for the F-16 was not received until 1101:13. At 1101:19, the F-16 pilot transmitted a distress call, and no subsequent intelligible transmissions were received.

Several witnesses observed both airplanes in the moments leading up to the collision. One witness, located adjacent to the west branch of the Cooper River, noticed the Cessna flying overhead, roughly from west to east, and then observed the F-16 flying overhead, roughly from north to south. He estimated that the two airplanes collided at an altitude of about 900 ft. He further described that both airplanes were "very low." The F-16 struck the left side of the Cessna, and debris began falling. He reported that a large black cloud of smoke appeared after the collision but did not observe any fire. He stated that neither airplane appeared to conduct any evasive maneuvers before the collision. After the collision, the F-16 then "powered up," turned right, and flew southbound along the river.

Another witness reported that he was standing in his backyard overlooking the river. He watched as the Cessna flew by from west to east. He next saw the F-16 flying toward the Cessna, coming from the Cessna's left rear position, roughly north to south. When the F-16 collided with the left side of the Cessna, debris started falling, with some landing in his yard. He stated that it looked as if the F-16 tried to "pull up" just before impact. After the impact, the F-16 turned right and flew along the river to the south and out of sight. Once the F-16 was out of sight, he heard several loud "bang" noises.

ATC radar continued to track the F-16 as it proceeded on a southerly course. After it descended to 300 ft, radar contact was lost at 1103:17 in the vicinity of the F-16 crash site. The F-16 pilot used the airplane's emergency escape system (ejection seat) to egress, incurring minor injuries as he landed on the ground under canopy. He was subsequently met by first responders. Figure 1 shows the calculated flight track for the F-16 and the Cessna.

PERSONNEL INFORMATION

F-16 Pilot

According to USAF personnel, the pilot of the F-16 was current and qualified in the accident airplane as a four-ship flight lead. His additional duties at the time of the accident included the position of 55th Fighter Squadron Chief of Mobility. At the time of the accident, he had accumulated 2,383 total hours of military flight experience, including 624 hours in the F-16. The pilot's total flight experience included 1,055 hours at the controls of the MQ-1B (Predator) and 456 hours at the controls of the MQ-9 (Reaper), both unmanned aerial vehicles. (The remaining hours were in USAF training aircraft and flight simulators.) His recent experience included 35 hours in the 90 days before the accident and 24 hours in the 30 days before the accident, all in the F-16. The USAF reported that the pilot was medically qualified for flight duty and was wearing contact lenses at the time of the accident.

The F-16 pilot's most recent instrument checkride was completed on August 25, 2014, and his most recent mission (tactical) checkride was completed on March 24, 2015. According to USAF records, none of the pilot's post-pilot training checkrides contained discrepancies or downgrades.

The F-16 pilot reported during a postaccident interview that he had accumulated about 50 hours of civilian flying experience and possessed an FAA-issued commercial pilot certificate obtained through 14 CFR 61.73. He had not flown civilian aircraft since he began initial USAF pilot training in July 2005.

Cessna Pilot

The pilot of the Cessna held a private pilot certificate with a rating for airplane single-engine land issued on December 29, 2014. His most recent, and only, FAA third-class medical certificate was issued on February 7, 2013, with no waivers or limitations. The pilot's personal flight logbook was recovered from the wreckage and contained detailed entries between May 2012 and July 5, 2015. As of the final entry, the pilot had accumulated 244 total flight hours, of which 239 hours were in the accident airplane make and model. He had flown 58 hours in the 90 days before the accident and 18 hours in the 30 days before the accident. Review of FAA records revealed no history of accidents, incidents, violations, or pending investigations.

The Cessna pilot's primary flight instructor indicated in a postaccident interview that the pilot was "very careful" and "responsive." He stated that the pilot "enjoyed" talking to ATC and was aware of the benefits. During his instruction, he would contact ATC for flight-following without being prompted. A review of the pilot's logbook revealed that he communicated with SSC ATC on at least 9 occasions and CHS ATC at least 21 times.

Air Traffic Controller

The CHS approach controller was hired by the FAA in August 2006 and attended the FAA academy in Oklahoma City before working at the Oakland Air Route Traffic Control Center. She resigned from the FAA in September 2007 and was rehired in February 2008. She worked at CHS since her rehire. Before working for the FAA, she served as an air traffic controller in the USAF from 1998 to 2000.

The controller was qualified and current on all operating positions at CHS and held no other FAA certifications. Her most recent FAA second-class medical certificate was issued on May 21, 2014, with a requirement to wear glasses while providing ATC services. She was wearing glasses on the day of the accident.

On the day of the accident, the controller was working a regularly scheduled 0700 to 1500 shift. At the time of the accident, she was working the radar west position combined with the radar east position, which was the normal radar configuration at CHS. The radar assistant position, called radar handoff, was also staffed. About 1101, when the accident occurred, she had been working the radar west position for about 1 1/2 hours.

AIRCRAFT INFORMATION

Cessna

The white- and red-colored Cessna 150M was a single-engine, high-wing airplane with a conventional tail. It was equipped with a rotating beacon light, anticollision strobe lights, navigation position lights, and a landing light. The operational status of each lighting system at the time of the accident could not be determined. Review of the airplane's maintenance and airworthiness records revealed no evidence that any supplemental equipment, such as high intensity anticollision lights, had been installed after delivery to enhance its visual conspicuity. The airplane was not equipped with a traffic advisory system (TAS), traffic alert and collision avoidance system (TCAS), or automatic dependent surveillance-broadcast (ADS-B) equipment or displays.

The Cessna was equipped with a King KX 155 single VHF communication radio, a King KT 78 mode C transponder, and an Ameri-King AK-350 altitude encoder. Review of maintenance records revealed that the most recent transponder and encoder tests per the requirements of 14 CFR 91.413 were completed on September 8, 2008. On July 20, 2012, an overhauled transponder and new altitude encoder of the same makes and models were installed. The units were ground tested in accordance with the procedures outlined in their respective maintenance manuals, but the maintenance records did not note any tests in accordance with 14 CFR 91.413. The pitot/static system was most recently tested per the requirements of 14 CFR 91.411 on April 11, 2013. The Cessna's most recent annual inspection was completed on October 14, 2014. At the time of the inspection, the airframe had accumulated 3,651 total hours of operation.

Air Force F-16

The gray-colored F-16 was a single-seat, turbofan-powered fighter airplane. Its most recent 400 hour phase inspection was completed on June 4, 2014, and it had accumulated 237 flight hours since that time. After a flight on June 11, 2015, USAF maintenance personnel completed work on the airplane's flight control system and subsequently cleared the airplane to return to service on July 2, 2015. At the time of the accident, the airframe had accumulated 4,435 total hours of operation. The airplane was not equipped with a TAS, TCAS, or ADS-B equipment or displays.

The USAF provided general information about the limitations of the F-16 radar and "identification friend or foe" (IFF) systems (more specific information is sensitive). The F-16 was equipped with a radar unit installed in the nose of the airplane that the pilot could use to locate and "lock on" to other aircraft. The radar was forward looking and limited to a search area spanning 120º directly in front of the F-16 (60º either side of center). The radar was also limited by the size of the target and was normally used to identify targets within a 40-mile range, but other settings were available. According to USAF personnel, the radar unit was designed to acquire fast moving enemy aircraft (not slow-moving, small aircraft). USAF personnel did not believe the radar would locate a small general aviation aircraft at takeoff or climb speed. The radar acquired targets by direct energy return off the target aircraft's surface and used aircraft closure rate rather than the airspeed of the other aircraft to filter out slow-moving targets.

When operating in search target acquisition mode, traffic was displayed as a small, white square target on the radar's multifunction displays (MFD), which were located on the cockpit instrument panel, near the pilot's knees. If a target existed, a subsequent sweep of the radar would reveal a new target, and the previous image would be lighter in intensity. There were no aural alerts if a new target appeared. The pilot could place a cursor over the target and "lock" the target on the radar if he/she chose. After locking on, the pilot could obtain the mean sea level (msl) altitude of the target.

The F-16 was also equipped with an IFF interrogator. Targets identified by this system would be displayed on the MFD, but it was not an integral part of the radar. The IFF interrogator could be programmed to request specific types of responses (1 to 4); most civilian aircraft with an operating ATC transponder would provide a "type 3" response. To receive any type of response, the F-16 pilot would have to manually initiate the interrogation process, which takes about 8 to 10 seconds to sweep and display all four types of responses, each being displayed for about 2 seconds.

The F-16 was equipped with a basic autopilot providing attitude hold, heading select, and steering select in the roll axis, and attitude hold and altitude hold in the pitch axis. There was no capability for autopilot-coupled instrument approaches. There were three bank settings: go-to heading, selected steer point, and hold bank angle. While the autopilot was engaged in heading select mode and a new heading was selected, the airplane would turn at about a bank angle not to exceed 30º. According to the F-16 flight manual, the autopilot was able to maintain altitude within ±100 ft under normal cruise conditions. Manual inputs through the control stick would override autopilot functions. If specific limits were exceeded during manual override, the autopilot would disconnect.

METEOROLOGICAL INFORMATION

The area forecast that included eastern South Carol

NTSB Probable Cause

The approach controller's failure to provide an appropriate resolution to the conflict between the F-16 and the Cessna. Contributing to the accident were the inherent limitations of the see-and-avoid concept, resulting in both pilots' inability to take evasive action in time to avert the collision.