Senate joins probes into Boeing 737 MAX

Sen. Ted Cruz will hold a Commerce subcommittee hearing next Wednesday examining the U.S. government's oversight of the Boeing 737 MAX, which has suffered two fatal crashes since October, leading to the grounding of the global fleet.

Between the lines: Cruz, who chairs the subcommittee on aviation and space, is seeking information on what various agencies knew about the plane's safety and where oversight processes may have gone wrong. Top officials from the FAA, the National Transportation Safety Board and the Department of Transportation will testify. Topics will include similarities between the two crashes, one in Indonesia in October and the other last week in Ethiopia.

The big picture: In holding the hearing, Cruz will complement a House inquiry already underway in that chamber's transportation committee. In addition, Boeing is also facing investigations from the Transportation Department's Inspector General, Justice Department, and other entities that are also investigating how the 737 MAX was certified as safe to fly in 2017, and judged to be safe enough to continue to fly after the October crash of a Lion Air 737 MAX 8.

• Cruz plans to investigate what federal agencies learned between the first and second crashes, and how that played into the FAA's decision to delay grounding the plane in the U.S. until virtually every other affected country had done so.
• Another area of inquiry is how deferential the FAA was to Boeing in allowing the aerospace giant to self-certify much of the aircraft's production.

What we're watching: One item of particular interest is a software system known as MCAS, which was designed to prevent the plane from stalling, but which is suspected of causing both crashes by forcing the aircraft's nose downward.

Go deeper: What we've learned from the Boeing 737 MAX crashes