The deadly crash of an Amazon cargo plane at Miami International Airport is prompting questions about the safety practices of 21 Air, the North Carolina carrier that operated the flight, and Amazon’s decision to outsource its air network to multiple airlines. The Boeing 767 was landing at Miami International on Sept. 6 when it touched down at roughly 180 miles per hour, according to National Transportation Safety Board data. The crew briefly attempted to take off again, but the plane continued about 1,300 feet beyond the runway, struck two vehicles and caught fire. Five people were killed. All were workers for a company that cleans aircraft. Five others were injured. Cockpit voice recordings released by the NTSB indicate that automated warnings sounded as the plane approached. One pilot told the other that the aircraft was arriving too fast, but the crew continued with the landing rather than making a go-around and trying again. Ross Aimer, a retired airline captain and aviation consultant, described the approach as unstable from the start and said pilots are trained to abandon such landings when conditions deteriorate. The crew’s decision-making will be a central focus of the NTSB investigation, which has not yet determined a probable cause. The flight’s crew also had limited experience on the 767. The captain had been certified to fly the aircraft for less than five months, while the first officer had held the qualification for less than 18 months, according to investigators. Those details have renewed scrutiny of 21 Air. Former employees, including Karl Seuring, a pilot and former president of the company’s pilot union, say they raised concerns about the carrier’s safety culture before the crash. Seuring alleges that he was fired in 2022 after speaking up about safety standards and later filed a federal whistleblower lawsuit. A former safety director, Don Helmig, wrote in a 2021 email to the company’s owner that he saw problems throughout the operation and accused leaders of treating safety concerns as a public-relations exercise. Company leadership disputed those allegations in testimony connected to the lawsuit, saying 21 Air complied with federal rules and did not discourage employees from reporting concerns. Seuring also said the airline struggled to attract experienced pilots because its compensation was lower than at competing carriers. 21 Air has said its organization is focused on proper training, procedures and operational safety and that it will review the NTSB’s findings. The company has not publicly responded to requests for comment about the Miami crash beyond previous statements. Amazon said its use of outside carriers is common across the aviation industry and that the airlines in its network are certified by the Federal Aviation Administration. The company said safety includes protecting flight crews, airport communities and the workers who handle its cargo. Amazon currently contracts with nine airlines operating more than 100 aircraft, according to aviation data provider Cirium. The network includes large carriers as well as smaller cargo specialists. 21 Air operates eight aircraft for Amazon, including the plane involved in the Miami crash, and also flies for DHL. The crash is the third major accident involving a Boeing 767 flying for Amazon. In 2019, an Atlas Air 767 crashed into Trinity Bay while approaching Houston, killing the two crew members and one passenger. The NTSB attributed that crash to pilot error. In 2024, a Cargojet 767 overran a runway at Vancouver International Airport after the crew reported problems with the aircraft’s wing flaps. No one was injured in that incident. NTSB Chair Jennifer Homendy said investigators are examining how Amazon and 21 Air divide responsibility and what safety requirements are included in their contracts and operating policies. She also urged anyone with information relevant to the investigation, including information about prior safety complaints, to share it with investigators. The investigation remains ongoing, and officials have not said whether the crash resulted from crew decisions, aircraft performance, company practices, weather or a combination of factors. For Miami, the inquiry extends beyond the cause of one runway overrun: It could help determine how much oversight major retailers should exercise when their delivery networks rely on smaller airlines operating over populated communities and busy airport facilities.