The US Federal Aviation Administration (FAA) says it expects to receive Boeing's proposed software enhancement package for the grounded 737 MAX "over the coming weeks" after the company had previously said it planned to submit the fix for government approval by last week.
FAA spokesman Greg Martin said time was needed for additional work "as the result of an ongoing review of the 737 MAX Flight Control System to ensure that Boeing has identified and appropriately addressed all pertinent issues."
Boeing did not immediately comment on the FAA's statement.
The company said earlier on Monday it continues to work with the FAA and other regulatory agencies on the certification of the update.
Boeing also said last week it had reprogrammed software on its 737 MAX passenger jet to prevent erroneous data from triggering an anti-stall system that is under mounting scrutiny following the two deadly nose-down crashes.
With the new software installed, the anti-stall system would only kick in after sensing a problem. It would also be disabled if two airflow sensors that measure the angle of the wing to the airflow offer widely different readings.
