RELATIONS between the two members of each Philadelphia Airport explosives-detection K9 team are harmonious, despite the cop being a city employee and the dog being owned by the federal government. There's never any fed-local barking and scrapping.

The idea for using dogs at airports was born in 1972 after a TWA jet left New York for L.A. and returned after an anonymous warning of a bomb on board.

A dog named Brandy found the explosive 12 minutes before it was to detonate, and then-President Richard Nixon ordered the secretary of Transportation to develop programs to combat threats to transportation. The result was the FAA Canine Explosives Detection Team program, later transferred to the Transportation Security Administration. It came to Philadelphia in 2002.

Law-enforcement units protecting transportation provide the human partner and receive TSA-trained dogs free, plus an annual $40,000-$50,000 stipend for each team. About 650 teams are deployed in the U.S.

Each team gets 10 weeks of intensive training at TSA's facility at Lackland Air Force Base in San Antonio. TSA requires annual testing for recertification.

TSA primarily uses Belgian Malinois, German shepherds, Hungarian Vizslas and Labrador retrievers because of their intelligence, sensory ability and independence.

Dogs come from domestic or foreign breeders and cost about $6,000 each, says TSA spokesman Greg Soule, with an additional $25,000 spent on training the team at Lackland.

TSA also has a puppy program, in which TSA breeds and trains its own dogs, primarily Labrador retrievers, with some Vizslas.

Dogs are used because their sense of smell is 1,000 times more sensitive than a human's.

- Stu Bykofsky