U.S. accident investigators who last year urged a broad overhaul of aircraft certification after two crashes of Boeing Co.'s 737 Max have endorsed fixes for the jet proposed last month by the Federal Aviation Administration.
A letter this week from Robert Sumwalt, chairman of the National Transportation Safety Board, said safety reviews by the regulators and proposed changes to pilot procedures had followed the board's recommendations.
The letter said that proposed pilot-procedure changes "are generally consistent with the intent" of the board's recommendation. Expanded FAA safety assessments in the process were also "positive progress" on meeting a separate recommendation issued by the safety board.
The letter is significant because the safety board is an independent agency and has been critical of the FAA's oversight of the Max. Investigators from the board participated in investigations of both crashes that led to the grounding of Boeing's bestselling plane in March 2019.
The FAA will review the comments filed in the case before deciding on whether to formally approve a set of fixes to the plane so that the grounding order can be lifted. Comments are due by Monday.
Boeing hopes to return the plane to service this fall. A total of 346 people died in the crashes off the coast of Indonesia and in Ethiopia that were linked to a malfunctioning safety system that was repeatedly driving down the two jets' noses.
The safety board's comments stand in contrast to those from family members of victims in the March 10, 2019, Ethiopian Airlines crash, who are calling for a lot of additional work on the plane before it returns to carrying passengers.
"The airplane is aerodynamically unstable and does not comply with modern aircraft certification standards," they said. The letter, dated Thursday, was signed by more than 2,000 family members, friends and supporters.They essentially call for the FAA and Boeing to reevaluate the entire aircraft from scratch before approving its return. They want an added sensor for redundancy, an aerodynamic evaluation of the plane and extensive changes to the plane's pilot-alerting system.
While the Max, a redesigned 737 model, has a tendency to nose up in rare conditions as a result of its larger engines and a change in their positioning, there has been no finding in any of the investigations of the plane and the crashes that it is "unstable." The safety system implicated in the crashes was designed to address that problem and it's being redesigned to prevent such crashes in the future.
European regulators have said they want at least one of the family groups' suggestions, the equivalent of an additional sensor to improve reliability. The sensor measures whether the jet's nose is pointed above or below the oncoming air and it failed in both crashes.
However, the European Aviation Safety Agency has concluded that the issue is not a critical safety matter and can be addressed in fixes adopted later. While there has been no formal announcement of the plans, it appears Boeing may opt to create a computer-generated replica of the sensor instead of having to add new devices to thousands of planes.
The safety board, which has no regulatory power and only can urge government agencies and industry to adopt safety improvements, issued seven recommendations on the Max on Sept. 26, 2019.
It sought more scientific ways of testing pilots' reactions to emergencies, particularly ones that involved complex, multiple cockpit warnings such as those in the accident. Boeing had assumed pilots would respond within seconds to a malfunction of the flight-control feature involved in the crashes, but crews in both accidents were confused and lost control.