Some airline flights were canceled and others were delayed yesterday as a result of an electrical storm Thursday night that knocked out radar equipment at Baltimore-Washington International Airport.

Airport officials said late yesterday that they hoped to complete repairs to the airport's radar antenna by 5 a.m. today and resume a near normal flight schedule immediately thereafter.

BWI air traffic controllers were able to make limited use of radar equipment at National Airport Thursday night and yesterday, but they had to rely on visual contact when planes came within close range of the airport. For safety reasons, takeoffs and landings were separated widely, resulting in delays of several hours and cancellation of some commuter flights.

Linda Greene, a spokeswoman for the airport, said some incoming and outgoing flights were delayed yesterday for up to 90 minutes, and airline officials reported delays of two hours or more.

The antenna was hit by lightning about 4 p.m. Thursday. An FAA spokesman said incoming flights were rerouted to Dulles International and National airports until about 6 p.m. Thursday, when BWI controllers were able to get to National Airport and use radar scopes to guide planes to and from BWI. Officials said there were extensive delays for the rest of the evening.

Kathleen Bergen, a spokeswoman for the Federal Aviation Administration, said that controllers at Dulles, National and the FAA center in Leesburg maintained radar contact with the rerouted flights after BWI's radar equipment failed. "At no time was safety compromised," she said.

A spokewoman for USAir said that two of the airline's 28 flights yesterday were canceled and passengers were booked on other flights. Other airline officials said there were long lines at airline counters throughout the day.

Greene said that 80 percent of incoming and outgoing flights should be on schedule as soon as repairs are completed.