By Andy Pasztor and Andrew Tangel 

U.S. air-safety regulators for the first time publicly spelled out the full range of hardware, software, crew training and maintenance changes they are proposing before Boeing Co.'s 737 MAX jets will be allowed to resume flying passengers.

The 36-page document released Monday -- filled with detailed technical explanations and multiple new emergency checklists for pilots -- had been expected. Many of the four proposed design changes and extra equipment tests largely track the various safety enhancements Federal Aviation Administration officials began crafting even before the MAX was grounded globally in March 2019, following two fatal crashes that took 346 lives.

Still, the proposal marks a decisive moment for the MAX fleet, along with Boeing and its airline customers, because it signals that the FAA, foreign regulators and the company have reached consensus on the most important fixes and controversial technical details. Subject to a 45-day public comment period and what is likely to be weeks of additional FAA analysis and responses, Monday's move appears to keep the MAX on track for what government and industry officials project could be a return to widespread commercial service by early next year.

Before that can occur, however, the FAA will wait for the results of a series of independent technical reviews, simulator tests by international pilots and further public comments on specific pilot-training requirements. Those simulator sessions are projected to begin in three weeks at Boeing's pilot-training facilities at Gatwick Airport outside London, according to one person familiar with the details, though the timetable could slip.

A Boeing spokesman said: "While we still have a lot of work in front of us, this is an important milestone in the certification process."

The document technically covers only 73 Max airliners registered to U.S. carriers. But with few exceptions, foreign regulators and carriers appear poised to go along with the proposal for some 400 aircraft Boeing previously delivered around the world. Regulators in Canada, the European Union and Brazil, who have been most closely involved in the deliberations, are expected to follow the FAA's lead.

Another roughly 450 of the planes, which haven't been delivered to airlines, are expected to be subject to the same requirements before they can enter service. And jets rolling off the assembly line also will have to incorporate the eventual modifications.

As part of the FAA's action, the agency released an extensive companion report indicating the lessons learned from what it described as the work of more than three dozen agency experts, including pilots and engineers, plus analysis of some 4,000 hours of simulator sessions. In addition to the design failures and improper assumptions about pilot reaction time that played roles in both crashes, the report notes that the FAA has resolved "additional safety concerns beyond those identified during the accident investigations."

Between them, the two documents cover issues that have been central to the MAX's safety shortcomings, from automated flight-control systems prone to dangerously misfire to inoperative cockpit warnings to hazardous wiring that could cause electric short-circuits. The FAA, as expected, also proposed adding a safeguard by requiring both of the MAX's flight-control computers to operate simultaneously.

In addition, agency experts want enhanced sensor tests and "an operational readiness flight prior to returning each airplane to service."

A major goal of the safety effort is to provide pilots more timely and clear-cut information, cockpit warnings and memorized emergency procedures in the event of sensor malfunctions or other system failures. By reducing pilot workload in emergencies -- and eliminating the cacophony of conflicting warnings such as those crews experienced before the dual crashes -- the FAA aims to dramatically enhance the fleet's safety.

The FAA is proposing revisions to checklists pilots use in various emergencies, such as when they face contradictory cockpit readings and alerts.

Under the proposed changes, for instance, pilots would use a revised checklist for an emergency known as a runaway stabilizer, which can unexpectedly push the plane's nose down without pilot commands.

The new procedure would include memorized steps, such as one pertaining to thumb switches the pilot can use to level the aircraft's nose. Pilots' inability to recover using these switches were at issue in the two MAX accidents.

The MAX crisis has eroded trust in the Chicago plane maker among many customers, regulators and passengers, while sparking a flurry of federal criminal, civil and congressional investigations that are still under way.

Write to Andy Pasztor at and Andrew Tangel at


(END) Dow Jones Newswires

August 03, 2020 19:34 ET (23:34 GMT)

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