CHARLESTON, SC (WCSC) - The federal government has admitted that their employees' actions caused a deadly accident between a Cessna and an F-16 over Moncks Corner.
The planes collided in the morning of July 7, 2015 over the west branch of the Cooper River and near Old Highway 52.
Michael Johnson, 68, and his son, Joseph Johnson, 30, were killed in the crash.
"The United States admits that its employees' acts and omissions proximately caused the subject accident and resulted in the deaths of Michael and Joseph Johnson," read a statement by the US Attorney's Office in court records released on Thursday."Accordingly, the United States does not contest its liability for their deaths in this case but does contest the existence, type and quantum of damages available to Plaintiffs."
The government's statement was in response to a lawsuit filed in connection to the deadly collision.
According to investigators, the F-16 continued to fly approximately two-and-a-half minutes after the crash during which its pilot, later identified as Maj. Aaron Johnson, was able to eject from his aircraft before the jet crashed.
The F-16 crashed into land approximately six nautical miles from the collision location.
At the time of the collision, the F-16 was en route to Charleston, where the pilot planned to perform a practice instrument approach.
The Cessna had departed from a non-tower-controlled airport in Moncks Corner four minutes before the accident on visual flight rules, NTSB officials said.
In previous reports, investigators said the two pilots most likely did not see each other until it was too late.
According to the National Transportation Safety Board, the probable cause of the mid-air collision was "the approach controller's failure to provide an appropriate resolution to the conflict between the F-16 and the Cessna, contributing to the accident or the inherent limitations of the see and avoid concept, resulting in both pilots' inability to take evasive action to avoid the collision in time."
The controller, investigators say, expected the Cessna's would remain within the local traffic pattern at Moncks Corner. But as the Cessna climbed above the altitude of 1,100 feet and the airplane closed within 3.5 miles, she recognized the potential for a possible collision between the planes and transmitted the traffic advisory.
The planes were closing on each other at a rate of about 300 knots at that point, authorities said.
Avoiding a crash between the two planes would have required the F-16 pilot to first see and then take action to avoid the Cessna, according to the NTSB.
"While the controller tried to ensure separation, her attempt at establishing a visual separation at so close a range and with the airplanes converging at such a high rate of speed left few options and a visual separation could not be obtained," said Dennis Diaz, the NTSB Investigator-in-Charge at the time.
Diaz said the controller's instruction to the F-16 pilot to "turn left" was not contrary to FAA guidance for air-traffic controllers, but that it was the "least conservative decision" and most dependent on the F-16 pilot's "most timely action" for its success.
In hindsight, the controller should have instructed the F-16 to turn before the planes came in close proximity to each other and and to turn right, which would have kept the F-16 from crossing in front of the Cessna's path, he said.
Investigators say the controller's conditional response may have resulted in "a slight delay" in the F-16 pilot beginning the turn.
"The controller repeated the instruction and appended the word immediately, expecting that the F-16 pilot would perform a high-performance turn," Diaz said. "While the F-16 pilot began the turn before the controller completed her radio transmission, the rate of the turn was slower than what she had expected."
Investigators say post-accident interviews revealed the word immediately held "different meanings" to the controller and the pilot.
"Although the controller's use of the term immediately was in keeping with the guidance established, further clarification of her expectation, such as directing the pilot to expedite the turn would have removed any ambiguity," Diaz said.
NTSB investigators say the "see and avoid" concept, which relies on the pilot to look through cockpit windows, identify other aircraft, decide if the aircraft could be a collision threat and then take appropriate action has "inherent limitations."
Those include, investigators say, limitations of the pilot to visually process the information, other required tasks that compete with the requirement to scan for traffic, a limited field of view from the cockpit and weather conditions.
The Cessna was not equipped with any technology in the cockpit that would have displayed or alerted the pilot of traffic conflicts, Diaz said. The F-16 pilot's ability to detect other traffic, meanwhile, was limited to the "see and avoid" concept supplemented with air tower control advisories.
"While the F-16 pilot could use his airplane's tactical radar system to enhance his awareness of the radar system, it is designed to acquire fast-moving enemy aircraft and not slow-moving aircraft," Diaz said. "The F-16 was not equipped to display or alert traffic conflicts."
Diaz said their investigation showed both pilots would have had difficulty detecting the other plane.