Boeing Co. told customers and suppliers that the 737 MAX aircraft's return to service may not start until the middle of 2020, sending the company's shares tumbling Jan. 21.
"This updated estimate is informed by our experience to date with the certification process," Boeing said in a statement, reiterating its view that the U.S. Federal Aviation Administration and other global regulators will determine when the 737 MAX aircraft's grounding could be lifted.
Boeing also said that its expectation of further delays to the jets' return to service is "subject to our ongoing attempts to address known schedule risks and further developments that may arise in connection with the certification process."
Boeing will provide further updates during its quarterly earnings report next week. It expressed confidence that regulators will re-certify the 737 MAX.
Boeing shares tumbled by as much as 5.5% in early afternoon trading after CNBC first reported Boeing's expected further delay in the 737 MAX's return to service. The stock ended the trading day 3.3% lower.
Shares of U.S. airlines also fell Jan 21. Southwest Airlines Co.'s stock was down 2.7%, American Airlines Group Inc. shares closed 4.2% lower, and United Airlines Holdings Inc. dropped 4.4%.