Boeing got some good news for its 737 MAX when the European Union Aviation Safety Agency (EASA) signaled that the aircraft was safe to fly again and that the agency could recertify it in the near future. The EASA said the MAX could be back in the sky by the end of the year—though the third sensor mandated by the agency won’t be ready until 2022.
That sensor is a synthetic software-based sensor that would work alongside the two angle-of-attack (AOA) sensors each 737 MAX must be equipped with. Before the global grounding of the MAX fleet, the aircraft operated with only one AOA sensor—one prone to damage and malfunction, and which contributed to two fatal crashes. Boeing has proposed to add an additional AOA sensor to the jet, among other measures; the EASA went a step further by demanding the addition of the third sensor.
The sensor uses GPS, inertia measurements and a low-fidelity model of the aircraft to extrapolate the aircraft’s velocity and altitude in order to determine an independent reading of the plane’s position in the sky—more or less replicating the readings that an AOA sensor provides but through different means. Inertia and motion detectors can keep track of a plane’s change in direction, and GPS data helps boost their accuracy—while onboard computer processors should be able to synthesize and analyze the data quickly and responsively.
Including this sensor would add an important layer of redundancy to the AOA sensors’ input. Its data would be processed by the flight computer alongside the AOA sensors’ readings. Should one or both of the conventional AOA sensors fail—and they do have a history of malfunctions—the data derived from the synthetic sensor would still be reliable. Boeing’s 787 already has such a sensor, and Airbus is also installing similar technologies in its planes.
However, the technology still has room to improve. “The algorithms are complicated and certifying them is a bear,” said Demoz Gebre-Egziabher, a University of Minnesota aerospace engineering professor working on synthetic sensor systems. And because of the complexity of the system and the cost, it will take a while to equip the fleet of 737 MAXs flying in European airspace with the new sensor. The sensor will be installed in all 737s still in production and will be retrofitted to existing aircraft by 2022. The EASA appears to be willing to allow the aircraft to travel again while the sensor is on its way.
EASA chief Patrick Ky seems satisfied with the changes to the MAX. The agency is completing its documentation review and expects to issue a proposed airworthiness directive in December 2020, which will be followed by a four-week comment period. After that, it’s quite possible that the MAX will return to service in the European Union—a promising development for the troubled plane.
To add to the EASA’s optimism, some airlines are already making plans in anticipation of the aircraft’s imminent return to service. American Airlines is planning tours of the aircraft and Q&A sessions with technicians and pilots to help put passengers’ minds at ease about the plane’s safety. The airline is also planning to use the plane on its Miami-to-New York route—putting the MAX on the route starting on December 29. The carrier clearly anticipates that the plane will be cleared by the Federal Aviation Administration (FAA) by then.
“Based on what we’re hearing, that would allow for an ungrounding sometime in the month of November,” said American Airlines President Robert Isom. “If that holds true, that would allow us to be flying the aircraft a month later.”
In contrast, Southwest Airlines—which, like American, relies heavily on the 737 MAX—is less optimistic. The airline said it hopes Boeing’s aircraft is recertified by the end of 2020 but has yet to commit any of its planes to any routes.
U.S. pilot unions are also raising concerns about the jet’s return to service. Southwest’s pilots’ union has asked the FAA to significantly simplify its proposed emergency checklist, claiming that it’s far too long to reasonably expect pilots to remember and work through it in a crisis situation. And the union representing American Airlines pilots has asked the FAA to change its pilot emergency retraining process: the regulator is proposing that retraining occur every three years, while the union wants it shortened to every two years. The FAA’s comment period closed on November 2.
After two years on the ground, the 737 MAX is slowly inching its way back to recertification. But while this will be a major positive development for the troubled aerospace giant, Boeing still has a rough path ahead. The 737 crisis has damaged the company—but so has COVID-19, which has hammered the airline industry as a whole. In fact, Boeing recently announced its fourth straight quarterly loss, as well as its intent to cut its workforce by 30,000 by the end of next year.
The company has also significantly slowed its production, anticipating that next year it only will deliver about half of the 450 units it has stockpiled during the aircraft’s grounding. Boeing received no new orders for any of its aircraft—and the MAX was once its best-selling plane.
On the latest earnings call, Boeing CEO Dave Calhoun predicted that airline traffic in 2020 would only be about a third of the activity from the previous year.
But industry watchers still appear to be confident that the MAX will reclaim its position as the world’s most popular passenger jet. “I really believe that once the aircraft are back in service, with the growing environmental regulations, the growing need for efficiency and economical operations, I think the MAX will begin to gain favor,” said Steven Udvar-Hazy, chair of Air Lease Corporation, the influential aircraft leasing giant. “So, the 737 will make it back. But it’s suffered, and it’s going to take a while for its values to really reach equilibrium.”
Read more about the MAX’s return to service at FAA Chief Personally Tests the 737 MAX.