A Nippon Cargo Airlines Boeing 747-800, registration JA11KZ performing freight flight KZ192 from Chicago O'Hare, IL (U.S.) to Frankfurt Hahn (Germany), was in the initial climb out of O'Hare's runway 28R when the crew reported they flew through a flock of large birds, about 20-25 birds, at about 1,500 feet AGL, 4 or 5 birds hit the windscreen and were all over the windscreen.

The crew indicated that all systems were working normally and they wanted to carry on. The crew was handed off to departure frequency and was cleared to climb to 15,000 feet when the crew indicated they might return to Chicago to have that mess left by the flock of birds looked after.

After levelling off at 15,000 feet the crew decided to return to Chicago as a precaution to have the aircraft checked, they were not sure about their weather radar. The aircraft returned to Chicago for a safe landing on O'Hare's runway 28C about 25 minutes after departure.

The occurrence aircraft is still on the ground about 20 hours after landing back.