US FAA released a final albeit interim rule finalizing slot limits at Chicago O'Hare that originally were imposed on a temporary basis in 2004.The rule takes effect Oct. 29, 2006, and terminates Oct. 31, 2008, at which point it is expected that the opening of a new runway under the O'Hare Modernization Plan will allow the airfield to accommodate more than "50,000 additional forecast operations" annually.

The ruling covers arrivals from 7 a.m. through 8:59 p.m. Central time on weekdays and from noon through 8:59 p.m. on Sundays. The number of arrival slots during those periods will be limited to 88 per hr. and to 50 during each 30-min. period from 7 a.m. through 7.59 p.m. The number of slots rises to 98 between 8 p.m. and 8:59 p.m. Monday through Friday and Sunday, with the 50-per-half-hr. limitation applying. FAA also will control sale and lease of slots between airlines, which must use the slots 80% of the time or lose them.

The agency estimated that the final rule will reduce delays at the airport by 32%, generate $475.6 million in savings through 2008, including $212.7 million for airlines, and cost less than $1 million. It added that it expects long-term solutions like airport and air traffic control modernization to eliminate the need for the regulations after their 2008 expiration.