A Boeing 777X performs during the Dubai Airshow, in Dubai, United Arab Emirates, November 14, 2021.
A Boeing 777X performs during the Dubai Airshow, in Dubai, United Arab Emirates, November 14, 2021. Reuters / RULA ROUHANA

Boeing Co is preparing for a new delay in the 777X program that would push first deliveries by at least a year into early 2025, a source briefed on the matter told Reuters.

The delay is in line with an estimate given by the plane's biggest customer - Emirates Airlines - whose president, Tim Clark, told Aviation Daily in an April 7 story he did expect to receive its first Boeing 777X before 2025.

The source confirmed the delay, first reported Friday by the Air Current aviation industry publication that said Boeing expects to delay the certification target until late 2024 - or by another nine to 12 months for the wide-body aircraft - with deliveries to follow in 2025.

The source spoke on the condition of anonymity because the revised target date had not yet been publicly released.

Reuters reported last month the Federal Aviation Administration (FAA) warned Boeing in a March 21 letter that existing certification schedules for the 737 MAX 10 and 777X were "outdated and no longer reflect the program activities."

Boeing had earlier said it expected to win certification for the 777X by the end of 2023. Certification is needed before Boeing can begin deliveries.

Asked about the delay report, Boeing said in a statement Friday it remains "focused on working transparently with regulators and our customers."

The 777X, known as the 777-9 and a larger version of the 777 wide-body jet, has been in development since 2013 and at one point was expected to be released for airline use in June 2020.

Boeing is also working to gain approval for the 737 MAX 10 by the end of the year and ahead of a key safety deadline set by Congress.

The FAA in March asked Boeing to provide a "mature certification schedule" for the MAX 10.

A 2020 law sets a December 2022 deadline for imposing a new safety standard for cockpit alerts. Only Congress can extend the deadline if the FAA does not certify the 737 MAX 10 by then.

In May 2021, the FAA told Boeing that, realistically, it would not certify the 777X until mid- to late 2023 and rejected a request by Boeing to clear a certification hurdle, citing numerous concerns about lack of data and the lack of a preliminary safety assessment for the FAA to review.

Boeing is also working to resume 787 Dreamliner deliveries. Reuters reported Wednesday it advised key airlines and parts suppliers that deliveries would resume in the second half of 2022.

Boeing's swollen 787 inventory, amassed since it halted deliveries nearly a year ago over structural flaws, has locked up desperately needed cash and cut airline capacity.