The Mystery of the Cracked Airplane Windshields

Feb. 18, 2007 — -- Investigators at the Denver International Airport are trying to figure out why the windshields on at least 13 planes have cracked.

Winds reaching up to 100 miles-per-hour have been whipping through the Colorado foothills, but airport officials say they've never seen anything like this. The weather was so cold and windy this weekend that parts of Colorado's Interstate 70 were in a near whiteout, and some ski areas closed lifts.

On the tarmac and in flight, the weather has had damaging affects on airplane windshields.

"This is not only unusual, I know of no precedent for anything like this where multiple windshields have been cracked, simply by being in a particular place at a particular time," said John Nance, a pilot and aviation consultant for ABC News.

Birds, Weather Can Be Destructive

Aircraft windshields are designed to withstand air pressure at 400 knots and survive hitting a bird without catastrophic failure. But occasionally, they crack, and the pilots land as soon as practical.

"The two most likely causes of cracked windshields are simply the internal heat system being misapplied or not heating uniformly or having a bird hit it at a really high rate of speed in the air," Nance explained.

Cracks often are caught while the plane is on the ground. They can be terrifying when they happen in the air. The Federal Aviation Administration has records of 20 in-flight cracking incidents since 1982, 12 of them on commercial airliners.

Two years ago, when Oprah Winfrey's private jet suffered a cracked windshield after hitting a bird on takeoff. One of the most infamous cases of cracked windshields occurred in 1990, when a windshield panel blew out on a British Airways flight, nearly sucking the pilot out the window. The plane was still able to fly.

"It's certainly not going to destroy the airplane and it's not going to make it un-flyable," Nance said.

The FAA is investigating the Denver cases of cracked windshields because there have been so many of them, but all the affected jets are expected to be back in service today.