Moncks Corner, SC, USA
N3601V
CESSNA 150M
96-0085
LOCKHEED-MARTIN F-16CM
The pilot of the F-16, who was operating on an instrument flight rules (IFR) flight plan, was in contact with air traffic control (ATC) and was provided radar vectors for a practice instrument approach to Charleston Air Force Base/International Airport (CHS), Charleston, South Carolina; the F-16 descended to an altitude of about 1,600 ft mean sea level as instructed by the air traffic controller. Shortly thereafter, the Cessna departed under visual flight rules (VFR) from a nearby nontowered airport; the Cessna pilot was not in contact with ATC, nor was he required to be, and had not requested traffic advisory (flight-following) services. As the Cessna continued its departure climb, the airplanes converged to within about 3.5 nautical miles (nm) laterally and 400 ft vertically, triggering a conflict alert (CA) on the controller's radar display and an aural alarm. About 3 seconds later, the air traffic controller issued a traffic advisory notifying the F-16 pilot of the position, distance, and indicated altitude of the radar target that corresponded to the Cessna, stating that the aircraft type was unknown. When the F-16 pilot replied that he was looking for the traffic, the controller issued a conditional instruction to the F-16 pilot to turn left if he did not see the airplane. The F-16 pilot did not see the airplane and responded, asking "confirm two miles?" The controller responded, "if you don't have that traffic in sight turn left heading 180 immediately." As the controller began this transmission, the F-16 pilot initiated a standard rate (approximately) left turn using the autopilot so that he could continue to visually search for the traffic; however, the airplanes continued to converge and eventually collided about 40 seconds after the controller's traffic advisory notifying the F-16 pilot of traffic. (Figure 1 in the factual report for this accident shows the calculated flight tracks for the Cessna and F-16.) Air Traffic Controller and F-16 Pilot Performance During postaccident interviews, the controller reported that when she observed the Cessna's target on her radar display as it departed, she thought that the airplane would remain within its local traffic pattern, which was not the case. Therefore, it was not until the airplanes were within about 3.5 nm and 400 vertical ft of one another that the controller notified the F-16 pilot of the presence of the traffic by issuing the traffic advisory, which was about 3 seconds after the ATC radar CA alarmed. (Federal Aviation Administration [FAA] Order 7110.65, Air Traffic Control, paragraph 2-1-21, "Traffic Advisories," states, in part, that a controller should "Unless an aircraft is operating within Class A airspace or omission is requested by the pilot, issue traffic advisories to all aircraft (IFR or VFR) on your frequency when, in your judgment, their proximity may diminish to less than the applicable separation minima. Where no separation minima applies, such as for VFR aircraft outside of Class B/Class C airspace, or a TRSA [terminal radar service area], issue traffic advisories to those aircraft on your frequency when in your judgment their proximity warrants it. …") When the controller issued the traffic advisory, about 40 seconds before the eventual collision, the F-16 and the Cessna had a closure rate of about 300 knots. If the F-16 pilot had reported the Cessna in sight after the controller's traffic advisory, the controller likely would have directed the F-16 pilot to maintain visual separation, which is a common controller technique to separate aircraft. While the controller tried to ensure separation between the airplanes, her attempt at establishing visual separation at so close a range and with the airplanes converging at such a high rate of speed left few options if visual separation could not be obtained. The options available to the controller when issuing instructions to the F-16 pilot to avoid the conflict included a turn, climb, some combination thereof, or not issuing an instruction at all. (An instruction to descend was not an option because the F-16 was already at the minimum vectoring altitude for the area.) The controller indicated in a postaccident interview that she chose not to instruct the F-16 to climb because the altitude indicated for the Cessna's radar target was unconfirmed (the Cessna pilot had not contacted ATC). An element informing the controller's decision-making as to which instruction to provide was likely the flow of other traffic into the airport at that time. Arriving aircraft, including the accident F-16, were being sequenced to runway 15 via the final approach course extending from the approach end of the runway. Given the traffic flow, the left turn instruction to the F-16 would have kept the airplane on a heading closer toward, rather than farther from, its destination and would have made returning the F-16 to the intended final approach course much easier. However, the controller's instruction to the F-16 pilot to turn left required the F-16's path to cross in front of the Cessna. Although this decision was not contrary to FAA guidance for air traffic controllers, it was the least conservative decision, as it was most dependent on the F-16 pilot's timely action for its success. Further, the controller issued the instruction to turn left if the F-16 pilot did not have the Cessna in sight. The F-16 pilot responded to the controller's conditional instruction with a question ("confirm two miles?") that indicated confusion about the distance of the traffic. The F-16 pilot's attempt to visually acquire the Cessna per the controller's conditional instruction likely resulted in a slight delay in his beginning the turn. The collision likely would have been avoided had the F-16 pilot initiated the left turn, as ATC instructed, when he realized that he did not have the traffic in sight. About 7 seconds elapsed between the beginning of the controller's first conditional instruction to turn and the beginning of her subsequent conditional instruction to the F-16 pilot to turn "immediately." Analysis of the radio transmission recordings and the F-16's flight recorder data showed that, as the controller was making the subsequent conditional instruction, the F-16 pilot began turning to the left, which pointed his aircraft toward the Cessna. Due to the closure rate, the close proximity of the two airplanes, and human cognitive limitations, the controller did not recover from her ineffective visual separation plan, which placed the airplanes in closer proximity to each other, and switch to an alternative method of separation. The controller's best course of action would have been to instruct the F-16 pilot to turn before the airplanes came into close proximity with each other and preferably in a direction that did not cross in front of the Cessna's path. In postaccident interviews, the controller stated that when she issued the command to the F-16 pilot to turn left "immediately," she expected that the F-16 pilot would perform a high performance maneuver and that she believed that fighter airplanes could "turn on a dime." The FAA's Aeronautical Information Manual (AIM) Pilot-Controller Glossary defines "immediately" as a term used by ATC or pilots "when such action compliance is required to avoid an imminent situation." Further, the AIM states that controllers should use the term "immediately" to "impress urgency of an imminent situation" and that "expeditious compliance by the pilot is expected and necessary for safety." As described above, the F-16 pilot did not meet her expectation that the turn be conducted at a greater-than-standard rate. The controller's expectation of the F-16 pilot's performance was based on her assumption that a fighter airplane would perform a high performance turn to the heading; however, this expectation of performance was not clearly communicated. Based on the controller's instructions and the actions of the F-16 pilot in response, it is clear that the term "immediately" held different expectations for both parties. Although the controller's use of the term "immediately" was in keeping with FAA guidance, further clarification of her expectation, such as directing the pilot to "expedite the turn," would have removed any ambiguity. See-and-Avoid Concept According to 14 Code of Federal Regulations 91.113, "Right-of-Way Rules," "when weather conditions permit, regardless of whether an operation is conducted under instrument flight rules or visual flight rules, vigilance shall be maintained by each person operating an aircraft so as to see and avoid other aircraft." The concept that pilots are primarily responsible for collision avoidance was similarly stressed in US Air Force training documents. In addition, FAA Advisory Circular (AC) 90-48C, "Pilots' Role in Collision Avoidance," which was in effect at the time of the accident, stated that the see-and-avoid concept requires vigilance at all times by each pilot, regardless of whether the flight is conducted under IFR or VFR. (AC 90-48D replaced AC 90-48C in 2016 and contains the same statement.) The see-and-avoid concept relies on a pilot to look through the cockpit windows, identify other aircraft, decide if any aircraft are collision threats, and, if necessary, take the appropriate action to avert a collision. There are inherent limitations of this concept, including limitations of the human visual and information processing systems, pilot tasks that compete with the requirement to scan for traffic, the limited field of view from the cockpit, and environmental factors that could diminish the visibility of other aircraft. Factors Impacting the Pilots' Ability to Detect Other Traffic The collision occurred in a relatively low-density air traffic environment in visual meteorological conditions (VMC). The Cessna was equipped with an operating transponder and single communication radio but was not equipped with any technologies in the cockpit that display or alert of traffic conflicts, such as traffic advisory systems, traffic alert and collision avoidance systems, or automatic dependent surveillance-broadcast systems. The Cessna had departed from a nontowered airport and was still in close proximity to the airport when the collision occurred. The Cessna pilot had not requested or received flight-following services from ATC at the time of the collision, nor was he required to do so. Based on his proximity to the departure airport, it is reasonable to expect that the Cessna pilot likely was monitoring that airport's common traffic advisory frequency (CTAF) for awareness of airplanes in the vicinity of the airport, as recommended by the FAA's AIM. Based on statements from the Cessna pilot's flight instructor and from his logbook entries, which both cited past experience communicating with ATC, it is also reasonable to assume that had the collision not occurred, the pilot likely would have contacted ATC at some point during the flight to request flight-following services. Due to the Cessna's lack of technologies in the cockpit that display or alert of traffic conflicts and the pilot's lack of contact with ATC, his ability to detect other traffic in the area was limited to the see-and-avoid concept. While not required, had the Cessna been equipped with a second communication radio, the pilot could have used it to contact ATC while still monitoring the departure airport's CTAF. Had the Cessna pilot contacted ATC after departing and received ATC services, the controller would have had verification of the Cessna's altitude readout and its route of flight, which would have helped her decision-making process. The controller also could have provided the Cessna pilot awareness of the F-16. The F-16 was operating under IFR in VMC. The F-16 pilot's ability to detect other traffic was limited to the see-and-avoid concept, supplemented with ATC traffic advisories. While the F-16 pilot could use the airplane's tactical radar system to enhance his awareness of air traffic, it was designed to acquire fast-moving enemy aircraft rather than slow-moving, small aircraft and was thus unable to effectively detect the Cessna. (The radar system did detect a target 20 miles away, which is likely what led the F-16 pilot to question the location of the traffic that the controller had indicated was 2 miles away.) The F-16 was not otherwise equipped with any technologies in the cockpit that display or alert of traffic conflicts. The F-16 pilot did eventually visually acquire the Cessna but only when the airplanes were within about 430 ft of one another, about 1 second before the accident. A factor that can affect the visibility of traffic in VMC is sun glare, which can prevent a pilot from detecting another aircraft when it is close to the position of the sun in the sky. For the F-16 pilot, the sun would have been behind and to his left as the airplanes approached one another. Although the Cessna pilot would have been heading toward the sun, the sun's calculated position would likely have been above a point obstructed by the Cessna's cabin roof and would not have been visible to the Cessna pilot. Thus, sun glare was not a factor in this accident. Aircraft Performance and Cockpit Visibility Study Our aircraft performance and cockpit visibility study showed that, as the accident airplanes were on converging courses, they each would have appeared as small, stationary, or slow-moving objects to the pilots. Given the physiological limitations of vision, both pilots would have had difficulty detecting the other airplane. Specifically, the study showed that the Cessna would have appeared as a relatively small object through the F-16's canopy, slowly moving from the center of the transparent heads-up display (HUD) to the left of the HUD. As the F-16 started the left turn as instructed by the air traffic controller, the Cessna moved back toward the center of the HUD and then off to its right side, where it may have been obscured by the right structural post of the HUD. It was not visible again until about 2 seconds before the collision. (Figures 3a and 5a in the factual report for this accident show the simulated cockpit visibility from the F-16 at 1100:18 and 1100:56, respectively.) The F-16 pilot reported that before the controller alerted him to the presence of traffic, he was actively searching for traffic both visually and using the airplane's targeting radar. He reported that after the controller advised him of traffic, he was looking "aggressively" to find it. By the time he was able to visually acquire the Cessna, it was too late to avert the collision. Our investigation could not determine to what extent the Cessna pilot was actively conducting a visual scan for other aircraft. Our aircraft performance and cockpit visibility study showed that the F-16 would have remained as a relatively small and slow-moving object out the Cessna's left window (between the Cessna's 9 and 10 o'clock positions) until less than 5 seconds before the collision. Given the speed of the F-16, the Cessna pilot likely would not have had adequate time to recognize and avoid the impending collision. Cockpit Display of Traffic Information Although the Cessna and F-16 pilots were responsible for seeing and avoiding each other, our aircraft performance and cockpit visibility study showed that, due to the physiological limitations of vision and the relative positions of the airplanes, both pilots would have had difficulty detecting the other airplane. Research indicates that any mechanism to augment and focus pilots' visual searches can enhance their ability to visually acquire traffic. (AC 90-48D highlights aircraft systems and technologies available to improve safety and aid in collision avoidance, and our report regarding a midair collision over the Hudson River [AAR-10/05] states that "traffic advisory systems can provide pilots with additional information to facilitate pilot efforts to maintain awareness of and visual contact with nearby aircraft to reduce the likelihood of a collision. …") One such method to focus a pilot's attention and visual scan is through the use of cockpit displays and aural alerts of potential traffic conflicts. Several technologies can provide this type of al
HISTORY OF FLIGHTOn 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. Figure 1. Calculated flight track for the F-16 (yellow) and the Cessna (orange). (The first witness is located north of the collision point, and the second witness is located southwest of the collision point.) PERSONNEL INFORMATIONF-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 INFORMATIONCessna 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 over
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.
Source: NTSB Aviation Accident Database
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