A federal administrative judge ruled Thursday that stiff landing fees aimed at keeping smaller aircraft out of Boston's Logan Airport violate federal aviation law because they are discriminatory and unfair. A final decision on how to deal with the fee structure imposed last summer by the Massachusetts Port Authority rests with the Transportation Department, to whom administrative law judge Burton S. Kolko made his recommendations. The case has been seen within the aviation industry as a test over how much power the federal government intends to allow local officials and airport operators in dealing with air traffic congestion. A DOT spokesman said the department will decide by Dec. 17 whether to uphold Kolko's decision or come down with an alternative finding on the Boston airport fees, which have raised a storm of protests among private and business pilots and in the commuter airline industry. Kolko in his decision said the Logan fees ``are lacking in economic justification ... not fair and reasonable (and) are unjustly discriminatory'' toward private aircraft and smaller commuter planes. The judge said that Massport officials acted in violation of federal aviation laws and he concluded that the Transportation Department has legal grounds on which to take pre-emptive action to have the fees revoked. Massport officials said that since the fee structure has been in place, Logan has handled more passengers with fewer delays. ``It is unsettling then, that all the benefits ... could be dismantled if DOT accepts the recommendations issued today,'' the company said. The Transportation Department announced last summer that it planned to closely examine the so-called ``Pace Program'' enacted at Logan to curtail the volume of air traffic in and out of the busy Boston airport. After loud protests from private pilots and some commuter airlines, Congress included in its DOT appropriations legislation earlier this year a provision ordering the department to stop airport construction money for Logan if it concludes the fees violate aviation law and are not rescinded. Massport approved the higher landing fees for small aircraft last March, saying Logan's capacity ``is a finite resource, which must be managed wisely and efficiently in order to keep people moving with a minimum of delay.'' The airport's operators said they wanted to use Logan's limited capacity for airliner traffic and not private aircraft, maintaining that a large jetliner with up to 400 people aboard ``deserves a higher priority than a Cessna with two people on board.'' The new fee structure went into effect in July after a U.S. district judge ruled that the fees were not discriminatory. The higher fees have affected both private pilots and commuter airlines. The government said some commuter services were discontinued to Logan after the new fees went into effect, but that most commuters just passed the higher costs on to air travelers. While the conclusion Thursday by Kolko is little more than a recommendation to senior department officials on whether to take administrative action, it was hailed by private pilot groups and other critics of the Logan fees. John Baker, president of the Aircraft Owners and Pilots Association, called the law judge's decision ``well reasoned'' and said, ``It makes it clear once and for all this country has a national aviation system that must be regulated by appropriate federal authority.'' Jonathan Howe, head of the National Business Aircraft Association, said his group now ``looks forward to .. the final determination'' on the Massport fees by Deputy Secretary Mimi Dawson next month. ``The entire aviation community was gratified'' by Kolko's findings, said Edward W. Stimpson, president of the General Aviation Manufacturers Association, the trade group that represents builders of small aircraft.