Boycotts make strange bedfellows.

The refusal of union leaders to fly in American air space while Uncle Sam's traffic control system is manned by nonunion personnel is helping the cash flow of Air Canada, British Airways, Air France and Japan Air Lines, not to mention domestic bus and train services.

Since the air traffic controllers strike in early August, federal and postal unions here have told staffers not to fly in this country unless it is an emergency. Instead of flying out of National, Dulles or other airports, foreign-bound union VIPs have been taking side trips to Canadian airports to show their solidarity with out-of-work members of the Professional Air Traffic Controllers Organization, and to underscore PATCO's contentions that the airways are not as safe as they were before trainees, military personnel and allegedly rusty supervisors took over their jobs.

Domestic travel by U.S. union leaders, who frequently attend meetings, installations and other union business in various cities, has been curtailed for the duration of the strike. Some unions that normally send a national officer to banquets in Butte and Boise, have told far-flung locals they will have to make do with a telegram from their Washington leaders, rather than a flesh-and-blood officer to make a speech or present a prize. Union leaders and staffers who must travel beyond the Beltway now often take their own cars, trains or buses. Many of the union leaders (some of whom have more flight time than many U.S. Air Force generals) are suffering from long trips, made under less than ideal conditions, via ground travel.

Last week many U.S. unions attended an international postal-telegraph conference in Japan. Since Tokyo is not on Amtrak's schedule, union chiefs designated to make the trek had to resort to some rather ingenious, roundabout routes to get there. Washington-based delegates of the American Postal Workers Union, National Association of Letter Carriers and AFL-CIO's Public Employees Department (one of them John Leyden, former president of PATCO) had to take a train to Montreal, then fly Air Canada to Vancouver, B.C., then take Japan Air Lines to Tokyo and reverse the procedure to get back to Washington.

"I've been in so many cuss, cuss bus stations and crummy train depots," one union leader said, "I'm getting ulcers from the food, boils from sitting too long and fatigue from bus lag."

When AFL-CIO leaders -- from Washington, New York and other cities -- assembled in Chicago recently they did so by bus and/or train. Some, who thought a car pool was something rich people had in their limos, got together, then drove to and from the meeting rather than fly over America.

At the National Treasury Employees Union's Montreal convention in August, some delegates from the far west bused to Canadian airports to fly into Montreal. The union's Washington staff took the Montrealer, a train, up and back. At the convention, delegates voted to spend one day picketing with PATCO members so they took chartered buses to the nearest U.S. airport, in Vermont, marched, then bused back to Canada.

Vincent Sombrotto, president of the Letter Carriers union, said he has been in an airplane once since the strike started "and that was an emergency." He said his staffers have been instructed not to fly except in emergencies, and Sombrotto, a New Yorker, now goes home when he can by train. Sombrotto said in addition to supporting PATCO, he feels "it isn't safe up there" since most of the professional controllers are no longer controlling.

Another union officer, who encourages staffers to put "BUY AMERICAN" stickers on their car bumpers, and growls when he sees a Toyota or Mercedes in his parking lot, said "the 'buy American' thing is very important with us, but we have to support our brothers in PATCO , so we aren't flying on U.S. airlines until this is over."