Why a problem on the ground can affect flights thousands of miles away among other issues

Michael McCormick, a former airspace manager with the Federal Aviation Administration, said it could take days for airlines — many of which had to divert flights — to resume normal operations after officials lifted the grounding order.

Michael McCormick, a former airspace manager with the Federal Aviation Administration, said it could take days for airlines — many of which had to divert flights — to resume normal operations after officials lifted the grounding order.