WASHINGTON -- A federal watchdog says that since a deadly airline crash in 2009, the government hasn't kept its promise to ensure that major airlines are holding their smaller partners to the same safety standards.

The Transportation Department's inspector general faults the Federal Aviation Administration for not taking steps to encourage the big airlines "to consistently share safety information and best practices" with regional airlines that operate flights under contract for them.

That business link is known as code-sharing, by which one airline sells tickets for seats on a flight operated by another airline - United and United Express, for example.

More than half of all airline flights in the U.S. are operated by regional airlines.