Planes disappear in Germany

Bratislava, Slovakia

At least a dozen planes briefly disappeared from Central European radar screens on two occasions last week, and nobody knows why. Air traffic controllers in Slovakia, Germany, Austria, and the Czech Republic reported that radar information on positions of civilian passenger planes flickered in and out for nearly half an hour, and only voice contact with the pilots was consistently available. NATO was doing military exercises on both occasions, but it said it did not jam civilian signals. Some analysts fear that computer hackers could be to blame.