IF TWO CONSUMER GROUPS can get the Civil Aeronautics Board's support, people who like to smoke on airplanes may soon be sidling up to ticket counters and asking, "Gotta flight?" That day, which non-smokers might welcome and smokers dread, was brought a lot closer by this week's accord between Eastern Air Lines and Action on Smoking and Health (ASH) and the Aviation Consumer Action Project, one of Ralph Nader's litigation teams.

The two groups had complained to the CAB about 13 cases since 1973 in which Eastern personnel had allegedly refused to honor passengers' requests for seats in no-smoking sections or failed to crack down on smoking in those areas. On the eve of a CAB trial, the parties proposed a settlement under which Eastern will pay a $10,000 penalty for past offenses - and from mow on will pay an unprecedented amount of deference to non-smokers' concerns.

Under the plan, Eastern will make sure that non-smoking passengers on every flight are informed of their rights and will impress on all employees that the smoking restrictions are serious and sensitive. But the proposed pact does not stop there. It goes beyond the CAB's requirements by also committing Eastern to designate two-thirds of the seats on its shuttle flights and 60 to 65 per cent of the seats on all other flights as permanent, unshrinkable no-smoking areas. Those sections could be expanded to meet non-smokers' demands - but if more smokers show up than can be seated behind the permanent lines, the latecomers will apparently have to choose between not smoking and not taking that plane.

This system has been hailed by the consumer groups as a breakthrough and denounced by the Tobacco Institute as an "apparent cave-in" to "the tyranny of self-appointed zealots who contemptuously regard smokers as second'class citizens." Each camp has a point. The seating ratios are not entirely irrational, because about 65 per cent of adult Americans do not smoke. Yet airline passenger lists do not always reflect that average. Eastern, which has been counting for several weeks, reports that the percentage of smokers has not gone over one-third on any flight. Some other airlines' spokesmen say, however, that flights catering to business travelers may have a larger proportion of smokers, perhaps 40 or even 50 per cent.

The real question is not whether any particular percentage is appropriate but whether the airlines and the CAB should be imposing limits at all. Under the current rules, conscientious air carriers have been able to accommodate all non-smokers and most smokers as well, except on chock-full flights when a few smokers might wind up fidgeting in a no-smoking row. That flexibility strikes us as the most equitable and least contentious approach at this stage in the heated national debates about smoking, public health and personal choice. The CAB should tell the anti-smoking groups to back off. It's reasonable to make smokers sit in the back of the plane. But it isn't the airlines' business, or the government's, to decide how many passengers should be allowed to smoke.