Pilots Stephen Fox and John Caswell had flown planes for thousands of hours between them at the time of a jet crash that claimed their lives last week in South Carolina.

But federal records show neither man had the certification required to fly the Dassault Falcon 50 jet that slid off the runway of the Greenville Downtown Airport on Thursday, killing both of them and injuring two passengers on board.

Authorities identified Caswell, 49, of Port St. Lucie, as the pilot, but he wasn't certified to act as the "pilot in command" of a Falcon 50 jet, according to the Federal Aviation Administration's Airmen Registry. Caswell's registry entry shows he has a "second-in-command privileges only" for that type of aircraft, meaning he could only fly as a co-pilot with someone who has a pilot-in-command rating.

Fox, a 66-year-old Indian Rocks Beach man who owns two Pinellas County-based flights services companies, was identified as the co-pilot, but no Stephen Fox or Stephen George Fox in the registry has a pilot-in-command or second-in-command rating for the Falcon 50. Fox was certified only for visual flight and didn't have the rating required to fly an aircraft under instrument flight rules.

"He was not qualified to be on that flight deck, period," said Robert Katz, a Dallas, Texas-based flight instructor and veteran pilot who tracks plane crashes across the nation. "What we're looking at here is an unqualified crew."

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Pilots earn pilot-in-command certification from the FAA after completing hours of training specific to an aircraft. That Fox and Caswell lacked so-called type rating for the Falcon 50 indicates they haven't had training for that jet, Katz said.

Caswell was certified as an air transport pilot and flight instructor and had type ratings to fly Lear and Gulfstream jets, FAA records show.

"Each aircraft is its own animal," Katz said. "We're talking apples and oranges and pears."

The National Transportation Safety Board and the FAA are investigating the crash. NTSB spokesman Eric Weiss said Monday the agency is focused on collecting evidence at the scene and did not have information on the pilots' ratings. FAA spokeswoman Kathleen Bergen also could not confirm the pilots' ratings but said the Airmen Registry reflects the latest information available.

An NTSB investigator said at a news conference last week that Caswell and Fox had significant experience flying, with Caswell logging 11,600 hours and Fox 5,500 hours. The investigator did not address which aircraft type ratings the pilots held.

Airport officials said the plane appeared to land normally about 1:40 p.m. but then slid off the runway and fell 40 to 50 feet down an embankment at the end of the runway, causing the fuselage split behind the cockpit. Caswell died at the scene. Fox was pronounced dead at a local hospital.

Officials said visibility was not a factor in the crash.

Authorities said the two passengers on board were a married couple but have not released their names or where they live. The flight originated in St. Petersburg, according to the NTSB, but the airport has not been identified.

Fox is listed in Florida state records as the registered agent for Air America Flight Services Inc. and Clearwater Aviation. The companies are headquartered at the St. Petersburg-Clearwater Airport and provide executive flight charters, aircraft management, maintenance services and pilot training, according to their websites. Air America also has a location in West Palm Beach.

A friend of Fox's told the Tampa Bay Times last week that Fox ran the business with his sons. One of the sons, Travis Fox, declined to comment last week and did not immediately return messages this week.

A page on Air America's site features photos of a Falcon 50, a sleek aircraft with three engines that seats nine in a plush, leather-appointed cabin. The jet has a range of 3,400 miles and top speed of 400 knots, the website says.

FAA records show the Falcon 50 that crashed is owned by Global Aircraft Acquisitions LLC of Delaware. The plane was manufactured in 1982, making it 36 years old.

It was still unclear Monday if the plane had been hired as a charter. If so, the pilots were violating regulations governing charter companies and putting their passengers at risk by flying without the proper qualifications, Katz said. He said such a violation could void any insurance coverage on the aircraft.

Violating charter regulations could also lead to sanctions for a charter company, including revocation of its air carrier certificate, said Jacqueline Rosser, senior advisor at the National Air Transportation Association, a trade group in Washington, D.C.

A preliminary crash report is expected in two to three weeks and a full report will take 12 to 18 months.

Contact Tony Marrero at tmarrero@tampabay.com or (813) 226-3374. Follow @tmarrerotimes.