I always wondered what would happen if a bird hit the cockpit window. Now I know. According to an article on Yahoo!, U.S. airlines were advised to inspect all Boeing Co. 737 cockpit windows after two were damaged in flight. A crack or other damage to a cockpit window could cause potential danger including the loss of cabin pressure.

The proposed airworthiness directive follows similar action in July on all Boeing 747 jetliners after a cockpit window fell out, causing a rapid loss of cabin pressure and an emergency landing.

The FAA recommended repeated inspections of nearly 800 737-series models in the U.S. fleet to detect any cracks in vinyl supports or damage to glass panes. There are another 1,800 planes flown by airlines overseas that would qualify for inspections.

Boeing alerted airlines to the problem in May and recommended action.

The FAA said it received reports of partial window separations on two 737s. One experienced a loss of cabin pressure at 12,500 feet when edges of a window came loose. The other was flying at 29,000 feet when a similar failure occurred. There are several windows in a 737 cockpit.

In addition, the FAA is concerned that cracked vinyl supports would make the window more vulnerable to failing if struck by birds.