MIAMI (VINnews) — Former pilots for 21 Air, the cargo carrier operating the Amazon Prime Air jet involved in Sunday’s deadly runway crash at Miami International Airport, had raised concerns about the company’s safety practices, according to documents and testimony obtained by the Miami Herald.

Five people were killed when the Boeing 767 went through a fence and struck vehicles at the airport.

In a federal Labor Department dispute, former pilot Karl Seuring alleged that 21 Air gave pilots insufficient rest between flights, violated takeoff procedures and retaliated against him after he raised safety concerns.

Seuring’s attorney said the pilot believed the company’s lengthy preflight checklist and scheduling practices could create safety risks. Seuring later became head of the company’s pilots union before being fired.

21 Air denied the allegations. The company said Seuring was fired because he misrepresented his employment history and disputed his account of his departure from Delta Air Lines.

Another former 21 Air pilot, Don Helmig, resigned in 2021, saying management was ignoring significant safety problems. Former chief pilot Bruce Joseph also testified that at least three pilots had refused to fly because of safety concerns and that company executives had discouraged employees from formally reporting safety issues.

The allegations predate Sunday’s crash, but the documents do not establish that any of the reported safety concerns contributed to the accident.

Federal investigators are continuing to examine what caused the Amazon cargo jet to leave the runway.