Federal regulators head to Capitol Hill Wednesday following weeks of revelations about problems with the fatally flawed Boeing 737 Max, and as the world awaits a software fix and revised training program from the aircraft's manufacturer.
The Federal Aviation Administration's current acting administrator, Daniel Elwell, is expected to face questions from lawmakers about how the Max was certified, and what steps will be taken to assure a skittish flying public that the aircraft can safely return to the skies.
The Trump administration's nominee for the job, Stephen Dickson, will testify at a separate hearing. Dickson is a former Delta Air Lines executive and military pilot, and has not yet publicly commented on the 737 MAX or its grounding, which occurred days before his nomination was announced. In a Senate questionnaire prior to the hearing, Dickson identified safety as one of his qualifications for and priorities on the job.
The FAA is waiting on Boeing to complete a software update for its review. The 737 Max 8 and 9 were grounded worldwide after a second crash in Ethiopia two months ago that investigators have described as appearing similar to an October crash into the Java Sea. Between the Lion Air and Ethiopian Airlines crashes, 346 people were killed.
When Elwell testified in late March, about two weeks after the Ethiopian crash, he defended the agency's process for grounding the plane. Other countries that acted days earlier, he said, without the data that the FAA waited for.
Since then, news reports have revealed how the FAA certification process allowed Boeing officials with authority delegated from the FAA to certify their company's own work.
Elwell will be joined by the agency's executive director of aircraft certification, Earl Lawrence, and two officials from the National Transportation Safety Board, which represents the United States in the Indonesian and Ethiopian investigations.
Preliminary reports on both crashes have implicated a flight control system that Boeing designed to operate in the background, making the 737 Max fly like earlier versions of the workhorse jetliner. Maintaining enough similarities between the planes avoided costly pilot training programs, a fact Boeing touted as a selling point.
But that computerized stability program -- the Maneuvering Characteristics Augmentation System, or MCAS -- received faulty sensor readings in both the Lion Air and Ethiopian jets, and repeatedly pushed the planes' noses downward, and ultimately into steep dives. The pilots' attempts to overcome it were unsuccessful. As is standard practice, the preliminary reports did not lay blame for either accident.
The emergency flight procedure Boeing says pilots should rely on when the system malfunctions has not been substantially updated since the 1960s and is now under FAA review, CNN recently reported.
But Boeing admitted its software could be improved to break what it described as links in the chains of events that ended in the crashes.
Boeing did not perform a flight test of a scenario where the system malfunctioned, CNN has reported.
The New York Times reported Tuesday that pilot unions "expressed frustration" with Boeing in November -- after the Lion Air crash -- that it had not previously disclosed the presence of the MCAS system. One American Airlines pilot, Todd Wissing, was quoted as telling the company, "I would think that there would be a priority of putting explanations of things that could kill you."
Boeing did not immediately respond to a request for comment on the audio from CNN.
The company recently revealed that it knew as early as 2017 -- as much as a year before the Lion Air disaster -- that it was aware an indicator linked to the sensors was not functional in many 737 Max aircraft. It planned to deploy a fix in a regularly scheduled software update.
A person familiar with the matter admitted to CNN last week that the company had not deployed the fix, even after the Lion Air crash.
The testimony comes amid multiple probes -- including from federal prosecutors, Congress, the Transportation Department inspector general, and an international committee of aircraft regulators -- into the certification of the 737 Max generally and the FAA's process more specifically.