When night falls, the word "hope" shines brightly these days from the windows of the nine-story headquarters building of Corning Inc. in Corning, N.Y. At the suggestion of one of the company's employees, Corning decided to leave lights on around the building to spell out the word that signals the sentiments of its work force.

Corning is not alone in doing things a bit differently in these days of extra tension because of war.

All over the country this week, routine office and factory rhythms were disrupted by the outbreak of hostilities with Iraq. Scheduled events at companies were canceled. Speakers at corporate conferences decided it was too risky to fly. Companies rushed to issue directives to employees about air travel. Security plans were dusted off and put into effect. Companies such as PRC Inc. in McLean reiterated that they would continue to pay employees who were called to active reserve duty.

For many employees who have colleagues or family in the Persian Gulf, anxiety turned to fear. Portable televisions appeared on desks and radios proliferated. For a time, productivity took a back seat to monitoring the latest developments in the war. Some chief executives maintained a respectful silence, while others almost immediately issued statements.

It became clear that some executives, who are intrepid world travelers, would be staying off airplanes for a while.

On the day after the invasion, for example, Corning Inc. Chairman James R. Houghton convened the company's Mideast Preparedness Committee. One of the company's first actions was to suspend all commercial air travel for employees. After tomorrow, there will be no air travel for 30 days unless it is essential or approved by a division manager.

These are pretty dramatic steps, considering that air links are vital to a company like Corning because of its remote location in New York State.

"We are saying that at least for the next several days, making sure employees are safe is more important than traveling," said Richard Marks, senior vice president of human resources for Corning.

But even before Corning formally curtailed air travel, it called off an annual outlook and strategic planning meeting for 250 of its managers from all over the world. The meeting, which was scheduled for the last week in January, was to be held in Corning. The managers will be given videotapes and other materials instead of a trip.

Similarly, faxes and phones will be working overtime at many other companies that have decided to ground their employees.

"Corporate employees feel they want to keep their employees safe and sound," said Gloria Bohan, president of Omega World Travel in Falls Church. "A lot of them are pulling back. They are doing conference calling and faxing. They are laying low and seeing what happens."

American Telephone & Telegraph Co., for example, suggested to employees on Friday that "there might be safer alternatives {to air travel}, such as conducting business discussions via teleconferencing," said Herb Linnen, an AT&T spokesman.

Linnen stressed the company has no information on credible threats against domestic airlines, and it is not banning travel altogether. But AT&T is advising employees that travel now is a matter of "individual judgment" and certain conditions should be weighed, such as possible terrorist attacks or the consequences of canceling.

Other companies have put partial bans in place. Monsanto Co. in St. Louis has suspended all travel to Israel, the Middle East and North Africa. Trips to the Far East and Europe will require approval from the company's executive management committee.

General Electric Co. has not slapped on a travel ban, but the company is advising employees to use "extreme caution" in making travel plans. Xerox Corp. is not allowing travel to the Middle East.

John A. Rollwagon, chairman and chief executive of Cray Research Inc. in Minneapolis, told employees five days before the U.S. attack on Iraq that any decision to travel overseas now requires the approval of an executive vice president or the vice president of European operations if the destination is Europe. Employees already embarked on an international journey were advised to check with their executive vice president before continuing on another leg of the trip or returning.

The three domestic auto companies also have limited travel overseas to emergencies only because of concerns about terrorism and security.

Companies telling employees to stay close to home naturally has caused a dramatic decline in international airline travel. Omega's Bohan said that over the past few weeks international bookings are off 25 percent and are dropping steadily. "We have spent a lot of time canceling reservations we spent a long time making," Bohan said.

Business is so brisk in cancellations that Bohan has created a reserve of 30 travel reservationists for customers who need them to make or break travel arrangements at any time of the day or night. She said cancellation frenzy is furious in the Northeast.

The division of Marriott Corp. that handles lodging also is feeling the effect of corporate cold feet on air travel. Gordon Lambourne, a spokesman for Marriott Hotels, Resorts and Suites, said call volume was down 5 percent to 10 percent a day at its worldwide reservation center in Omaha, signaling that fewer rooms were being reserved. The majority of Marriott's hotel business comes from business travelers.

Bohan hopes that her clients get over their fear of terrorism, especially since security measures have been tightened at airports. She expects some companies will take this opportunity to rewrite their travel policies and tighten them. When the winds of war shift toward an end to the conflict, she feels business will return to normal. "Meetings are for establishing relationships," she said. "There is nothing that waxes so well as eye-to-eye contact or a handshake."