Safe aloft

NEW equipment rules for private planes, allowing United States air controllers to monitor plane movements in a broader area than before, are a positive move in the direction of safer air travel. Under the rules, small planes that have no reporting devices to report their altitude and position will need to stay at least 30 miles away from the nation's 27 busiest airports and keep their general altitude to less than 10,000 feet. The improvements, which will not take effect for another year, were ordered by the Federal Aviation Administration in response to a congressional call a year ago for greater use of transponder equipment to avoid near-collisions.

Private pilots protest that the new rules, which will be expanded again in 1990 to include more airspace, amount to an unwarranted curb on their freedom to fly without significantly improving safety. Only about half of the private plane fleet now carries the equipment, which costs about $1,800.

But the new FAA rule is a weakened version of a far stronger rule proposed in February; that would have applied to a 40-mile radius around 254 US airports. Lawmakers were deluged with 80,000 letters of protest from private pilots, and the FAA soon revised its order. The commercial airline industry, which pushed hard for the new rules, has complained vigorously of the rule scale-down.

All planes must have transponders if commercial airliners' collision avoidance systems are to be truly effective.

The FAA's new rule is a good step.