The US Federal Aviation Administration (FAA) has issued a notice ungrounding the B737-8 and B737-9 types, subject to the completion of relevant upgrades and retraining of pilots.

Under its Airworthiness Directive AD 2020-24-02, the FAA requires the installation of new flight control computer (FCC) software on all B737 MAX, the revision of existing Airplane Flight Manuals (AFM) to incorporate new and revised flight crew procedures, the installation of new MAX display system (MDS) software, the changing of horizontal stabiliser trim wire routing installations, the completion of an AOA sensor system test, and the carrying out of an operational readiness flight.

"The FAA must approve B737 MAX pilot training program revisions for each US airline operating the MAX and will retain its authority to issue airworthiness certificates and export certificates of airworthiness for all new 737 MAX aircraft manufactured since the FAA issued the grounding order," the regulator said. "Furthermore, airlines that have parked their MAX aircraft must take required maintenance steps to prepare them to fly again."

While the notice is effective immediately, the installation of the required modifications and the retraining courses necessary for the aircraft's actual return to service is expected to take another couple of weeks.

According to the ch-aviation PRO airlines module, the only three US-based operators of the B737 MAX family are United Airlines (fourteen MAX 9s delivered before the March 2019 grounding), Southwest Airlines (thirty-four MAX 8s), and American Airlines (twenty-four MAX 8s). All other carriers have to wait until the relevant local authorities issue the ungrounding notices.

Other key regulators, such as the European Union Aviation Safety Agency (EASA) and the Civil Aviation Administration of China (CAAC), have yet to outline their own respective plans for the ungrounding of B737 MAX in their respective jurisdictions. EASA has previously said that it would rely on FAA notices and would not impose additional checks on MAX operators.