NTSB report details final seconds before fatal midair collision at Pennsylvania airport

What began as a routine training flight for a Pennsylvania State Police helicopter crew ended in a mid-air collision that killed a Hershey emergency room doctor and injured two troopers, according to a preliminary report federal investigators released this week detailing the final seconds before impact.

The National Transportation Safety Board account of the Aug. 19 crash at Carlisle Airport in Cumberland County lays out, second by second, how a Cessna 150 flown by Dr. Paul Sokoloski, 57, struck the tail of a state police Bell 407GX helicopter that had already landed and was hovering over a grass field beside the runway. Sokoloski was killed. Cpl. Bryce Corman and Trooper Jason Mills, the two troopers aboard the helicopter, were injured and have since been released from the hospital.

The report does not assign a cause. Investigators say a final determination is still months away.

The numbers behind the collision

Just eight seconds separated the helicopter clearing the runway surface and the moment the Cessna crossed into the same airspace, according to the NTSB's account of the sequence. Radar and radio data recovered from both aircraft show the pilots were in contact and had coordinated their movements shortly before the collision.

According to the preliminary findings, the helicopter crew radioed their position on final approach, and Sokoloski asked whether they wanted him to extend his downwind leg to create more spacing. The instructor aboard the helicopter answered yes. Sokoloski then turned onto his base leg roughly 2,500 feet from the runway 28 threshold and continued his approach. Investigators say tracking data from his airplane was lost shortly after that turn.

Airport surveillance video reviewed by investigators shows the helicopter crossing the runway threshold and exiting toward the grass field. About 30 seconds later, the Cessna crossed the same threshold while the helicopter was still close to the runway. Witnesses and the recovered video, described in local coverage of the report, show the airplane behaving abnormally in its final seconds, its wings rocking left and right and its nose pitched up before the right wing dropped just before impact.

The collision scattered the airplane into four major sections — the engine compartment, wings, tail assembly and lower fuselage — across roughly 250 feet of ground. Investigators said post-accident examinations of both aircraft found no evidence of mechanical failure in either the airplane or the helicopter before they collided.

An uncontrolled field

Carlisle Airport, a general-aviation field in South Middleton Township operated by the Pennsylvania Department of Transportation's Bureau of Aviation, has no control tower. Pilots coordinate their own separation over a shared radio frequency, a common arrangement at thousands of smaller airports across the country that lack air traffic control. The state police helicopter crew was there that evening for a routine training exercise, one of the many the aviation unit flies each year in support of search-and-rescue and patrol operations statewide.

Sokoloski, of Hershey, was a physician on the emergency medicine team at Penn State Health, which called him a valued colleague in a statement issued after the crash. He held a pilot certificate and had flown out of the Carlisle airfield for years, according to people who knew him. The Cumberland County coroner's office ruled his death accidental, caused by injuries sustained in the collision.

Corman and Mills are both pilots assigned to the Pennsylvania State Police aviation unit, which operates a small fleet of helicopters based in Harrisburg used for aerial patrol, search-and-rescue missions and other law enforcement support across the commonwealth. Both troopers were treated at area hospitals; Corman was released within days, and Mills, who Gov. Josh Shapiro said suffered the more serious injuries, was released after a longer stay.

'A very violent crash'

In the hours after the collision, Pennsylvania State Police Acting Commissioner Col. George Bivens described the scene to reporters, saying the Cessna broke apart a short distance from where the helicopter went down, its rotor blades sheared away as the aircraft rolled onto its side. Shapiro, addressing reporters the night of the crash, credited the troopers for surviving what could have been a far deadlier outcome.

"Right now we don't know the details about why the pilot was flying in that pattern, altitude or in that manner. But we are going to find out," said Aaron McCarter, the NTSB investigator in charge of the case, describing the work that remains before investigators can explain what happened in the cockpit.

Neither the state police nor the NTSB has said whether the board is considering interim safety recommendations for uncontrolled airports while the investigation continues, though the agency routinely reviews traffic-pattern procedures and radio practices at towerless fields after fatal midair collisions, according to CBS News' reporting on the crash.

What happens next

The preliminary report is not the NTSB's final word. Investigators typically take twelve to eighteen months to complete a full aviation investigation, at which point the board will vote on a probable cause and may issue safety recommendations covering pilot training, radio procedures or traffic-pattern separation at uncontrolled fields like Carlisle. The agency has classified the case as a major investigation, according to ABC News' initial account of the crash.

The state police aviation unit has resumed normal flight operations, and Carlisle Airport has continued regular traffic since the runway reopened. Penn State Health has said it is focused on supporting Sokoloski's family and the colleagues who worked alongside him.

For now, the question at the center of the NTSB's work — why an experienced pilot flying a familiar traffic pattern ended up on a collision course with a helicopter he had just spoken to by radio — remains unanswered. McCarter said investigators are still working through the wreckage, recorded radio traffic and witness accounts to reconstruct exactly what happened in the moments before the crash.