On March 18, US FAA Acting Administrator Bobby Sturgell ordered the agency's principal maintenance inspectors to conduct an audit of airlines under their oversight to "reconfirm that commercial carriers operating within the United States have complied with all airworthiness directives."

The move was "prompted" by Southwest Airlines' "recent failure to comply with one such directive," FAA said. Added Sturgell, "While the data tell us flying is safer than ever, prudence dictates we take this additional precaution and conduct a special emphasis review." An initial review will be completed by March 28 and a full audit will be finished by "no later" than June 30, the agency said.

In an e-mail to airline executives, Associate Administrator-Aviation Safety Nicholas Sabatini wrote that "one carrier's noncompliance with ADs makes it necessary for us to validate our system for overseeing your management of this regulatory requirement ... This in-depth review will assure us, and you, that we have sufficient data to evaluate the AD system." He explained that inspectors would audit a "sample" of ADs applying to carriers' fleets. "I expect your full cooperation with this audit," he told airlines.