American Airlines canceled 850 flights Wednesday and may cancel more Thursday. The airline scrubbed 500 flights Tuesday. The cancellations are affecting tens of thousands of passengers, and they're happening because the airline is re-inspecting some wiring near the fuel tanks on its MD-80 jets.
Two weeks ago, it inspected the wiring — canceling hundreds of flights then as well — but federal regulators said they are still concerned.
American Airlines put out a statement saying it's grounding the planes for "technical compliance issues and not safety-of-flight issues."