The Federal Aviation Administration (FAA) informed Boeing that the work required to certify the 737 MAX 7 had not yet been completed. Boeing had a December deadline to win approval for planes.
In a letter to Boeing, Lirio Liu, the FAA's executive director of aviation safety, wrote that the agency had uncertainties over the documents submitted by the company.
The FAA recommended the company to submit all remaining System Safety Assessments by mid-September. If the company had met the deadline, it would have been able to complete certification work (and get FAA approvals for aircrafts) by December, as it planned.
According to the letter, as of Sept. 15, just under 10 percent of assessments have been accepted by the agency, while 70% of them are at review and revision stages.
Boeing planned to win regulatory approval for the 737 MAX 7 and 10 models before a new safety standard on cockpit alerts would be implemented in December.