DENVER -- Windshields are cracking again on planes coming into Denver International Airport.

The Federal Aviation Administration is investigating the cracked windshield of a United Express plane flight No. 5306 operated by GoJet. The plane was en route from Denver to San Antonio with 66 people on board.

Once in the air, the pilot noticed the crack in the windshield and radioed DIA to return to the airport as a precaution. A spokesman said the pilot did exactly what he should have done in that situation.

A spokesman for GoJet said they are looking into the situation.

The passengers were scheduled on other flights going to San Antonio Wednesday night.

There have been gusts of wind up to 54 mph at the airport, said 7NEWS Meteorologist Mike Nelson.

Six weeks ago, the windshields on 14 planes at DIA were cracked.

Air safety investigators said those cracks were caused by "foreign object debris."

Microscopic analysis of the 21 front and side windshields cracked during a storm revealed fine particles causing pitting that in turn caused cracking, National Transportation Safety Board investigator Jennifer Kaiser said in late February.

Only the outer layer of the triple-layer windshields cracked and none of the planes declared emergencies.