1.   According to some experts, pilots are taught to try to escape from a hijacked plane to prevent another takeoff.

2.   CTK said the plane had arrived in Strunkovice on Saturday and originally planned to depart Sunday, but bad weather prevented takeoff.

3.   The state government in Calcutta asked the air force for help to locate survivors, but bad weather and poor visibility prevented takeoff.

4.   Union activists from Sabena drove vehicles onto the runway at Brussels international airport Tuesday night to prevent the takeoff of a Swissair Airbus bound for Zurich.