THE WHITE HOUSE refused to get involved in the Eastern Airlines dispute a year ago; now it's accepting a role in the rail labor negotiations.

Why the change? In the case of Eastern, there clearly was no national emergency. Other airlines moved with alacrity to fill service gaps left by Eastern's retrenchment. In the case of the railroads, however, there still is industrywide bargaining and the prospect of a nationwide work stoppage is a prospective national emergency. The economy would lose huge chunks of gross national product if railroads failed to run for any length of time.A few years ago, the Association of American Railroads tried to assess the economic impact of a national rail strike. A two-week stoppage, the AAR said, would result in layoffs of 600,000 workers outside the railroad industry, and a four-week shutdown would hike that number to 1.1 million - in addition to the nearly 300,000 railroad workers.

Maybe that's the difference between the Eastern affair and the railroad dispute.

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BEING GOOD MAKES IT EASIER to be honest; at least that seems to be the case in customer relations.

A colleague had the recent misfortune to be transiting Dallas/Fort Worth Airport on a day when weather-inspired delays brought the key American Airlines hub to a virtual standstill. A couple of weeks later, Michael Gunn, American's senior vice president for marketing, sent an unsolicited letter of apology.

Mr. Gunn did more than apologize. He explained what happened and how the airline failed.

He said in part: "There was a point early in the afternoon when practically all . . . scheduled arrivals were diverted . . . due to the unsafe landing conditions at (DFW). As a result, most of the departures normally timed to follow these arrivals had to be canceled - the aircraft simply weren't on hand. In hindsight, as the weather conditions improved, we were overly optimistic in believing we could coordinate the return of these diversions while still maintaining some degree of order in our regularly scheduled flights. We simply lost control of the situation - and there's no good excuse for that."

Mr. Gunn's letter is impressive. He doesn't just blame the problem on conditions beyond the airline's control. He accepts that the company contributed to the problem. In short, he offered an honest explanation and apology.

The situation points out the problem inherent in the hub-and-spoke system: When things go bad, they go VERY bad. Also, even when the system works perfectly, I cannot resist commenting that Dallas/Fort Worth is one of the most inconvenient, poorly designed airports in which to change planes - unless one is a world-class sprinter.