In 2006, the data-driven method publicly demonstrated its value following the deadly crash of a Comair commuter plane trying to take off from the wrong runway at Lexington, Ky. The FAA scrubbed various databases to evaluate the extent of comparable hazards elsewhere. After analyzing years of pilot reports of similar runway confusion at other fields, the agency ordered improved signs, better tarmac markings and extra pilot warnings to prevent crews from inadvertently lining up for departure on an incorrect or dangerously short strip.

As the number of accidents dwindled, however, each one sparked more public scrutiny. In February 2009, distracted and inadequately trained pilots of a Colgan Air turboprop failed to recover from a stall approaching the Buffalo, N.Y., airport. The otherwise perfectly functioning aircraft plunged to the ground, killing 50 people.

That was the last deadly U.S. accident until April 2018, when a fan blade on a Southwest Airlines Co. jet ruptured at 32,000 feet. The engine's front cover was blown off and shrapnel punctured the fuselage; the plane landed safely but a passenger seated by a window sustained fatal injuries. There have been no fatalities on U.S. carriers since then.

Both accidents, nine years apart, prompted intense publicity, congressional criticism and a flurry of regulatory action. But throughout the period, a second industry-government safety push was intensifying. Safety experts further expanded data sharing by combining detailed written reports from pilots with radar information from air-traffic control and other data. This entailed analyzing information from tens of millions of flights and many more radar tracks, spanning multiple years.

As this follow-up initiative launched, "there was a high degree of skepticism that it would ever succeed," says Hassan Shahidi, president and chief executive of the Flight Safety Foundation, a global, nonprofit advocacy group. He was previously at Mitre Corp., which oversees the storehouse of voluntary safety information submitted by airlines and their employees. The common refrain from both industry and labor, Mr. Shahidi recalled, was "we will give you 24 months." By then, "we need to have a few examples of actually identifying and mitigating risks."

Soon enough, the stepped-up data analysis prompted changes to questionable flight paths that sometimes brought jetliners dangerously close to hilltops on approaches to Oakland, Calif. The result was new approach procedures and more accurate topographical data loaded into the collision-warning systems on planes.

All told, the FAA has established a total of 10 separate, voluntary reporting or data-sharing programs, covering everyone from airport workers to FAA engineers to technicians who maintain the agency's traffic-control equipment. Voluntary changes adopted in the U.S. include, among other things, more extensive pilot training to understand warning signs when flight-control computers are set improperly or when airplanes are approaching an incorrect runway, how to adjust engine settings to prevent internal ice buildup and using cockpit radars more effectively to avoid turbulence in clear weather. Over the years, airlines also have refined data systems to help spot troublesome engine reliability trends earlier and alleviate hazards posed by pilot fatigue.

From Europe to Asia to Latin America, Mr. Shahidi said "everybody is now trying to copy the U.S."

Recently, however, some red flags have appeared. Airlines and independent safety experts have warned that the manual flying skills of many pilots are eroding, primarily because most crews rely on autopilots for all but a few minutes of each trip. Experts believe that overreliance on autopilots can reduce the hand-eye coordination of pilots and their confidence in the unlikely event that automated systems go haywire.

For all its usefulness, data sharing remains vulnerable to abuse. Last year, the Transportation Department's inspector general sharply criticized Southwest Airlines management for impeding FAA oversight. Management and agency lapses resulted in Southwest carrying roughly 17 million passengers on more than 150 jets with suspect maintenance records, the auditors found. The same report disclosed repeated hazardous landing attempts by a Southwest jet amid gale-force winds that ended with both wingtips striking a Connecticut runway in 2019. FAA investigators complained about the airline's level of cooperation. A Southwest spokeswoman said the carrier maintains a culture of compliance and transparency with the FAA, including mechanisms to report concerns without fear of repercussions, "recognizing the safety of our operation as the most important thing we do."

Other carriers have sought to keep FAA officials from fully participating in data exchanges or probes of potentially dangerous operational slip-ups. Outside safety experts contend that excluding regulators violates the spirit of voluntary reporting and could result in creeping industry complacency.

Despite the sterling record of U.S. airlines, FAA chief Steve Dickson has stressed the need to expand voluntary reporting to include the design and manufacture of jetliners in order to shore up public confidence in the wake of the 737 MAX tragedies. "I don't think that you ever stop trying to earn the trust of the public," he told reporters in September after personally test-flying the revamped MAX.

"No matter what we have done in the past, or what we are doing now," he said "that's never going to be good enough."

Mr. Pasztor, who is writing a book about the history of air safety, recently retired from The Wall Street Journal, where he covered aviation since the mid-1990s.

(END) Dow Jones Newswires

04-16-21 1120ET