When Berkeley resident Nancy Kates arrived at Oakland International Airport to board JetBlue flight 472, she thought she was heading off on a routine journey to visit her mother in Boston. Instead she ended up in a standoff with Transportation Safety Administration officials over her bra.

In the post-Sept. 11 world of heightened airport scrutiny, Kates, like most travelers, is familiar with the drill: Take off shoes and belts, open the laptop, carry shampoo in 3-ounce bottles.

For Kates, on Sunday, though, the security check got too invasive. A big-busted woman wearing a large underwire bra, she set off the metal detector. She was pulled aside and checked by a female TSA agent with a metal-sensitive wand.

"The woman touched my breast. I said, 'You can't do that,' " Kates said. "She said, 'We have to pat you down.' I said, 'You can't treat me as a criminal for wearing a bra.' "

Kates asked to see a supervisor and then the supervisor's supervisor. He told her that underwire bras were the leading item that set off the metal detectors, Kates said.

If that's the case, Kates said, the equipment must be overly sensitive. And if the TSA is engaging in extra brassiere scrutiny, then other women are suffering similar humiliation, Kates thought.

The Constitution bars unreasonable searches and seizures, Kates reminded the TSA supervisor, and scrutinizing a woman's brassiere is surely unreasonable, she said.

The supervisor told her she had the choice of submitting to a pat-down in a private room or not flying. Kates offered a third alternative, to take off her bra and try again, which the TSA accepted.

"They tried to humiliate me and I was not going to be humiliated over this," Kates said. "If I was carrying nail clippers and forgot about them, I wouldn't have gotten so upset. But here I was just wearing my underwear."

So she went to the rest room, then through the security line a second time. Walking through the airport braless can be embarrassing for a large-chested woman, not to mention uncomfortable. The metal detector didn't beep on the second time through, but then officials decided to go through Kates' carry-on luggage, she said.

The whole undertaking took 40 minutes, Kates said, and caused her to miss her flight. JetBlue put her on another one, but she was four hours late getting to Boston.

"It's actually a little funny in a way, but a sad, sad commentary on the state of our country," Kates said. "This is bigger than just me. There are 150 million women in America, and this could happen to any of them."

TSA spokesman Nico Melendez said Monday that he wasn't familiar with the incident. But he said in all circumstances, "we have to resolve an alarm."

That's the case for bras, artificial hips or anything with metal that sets off an alarm, he said. "Unfortunately, we can't take a passenger's word for it."

Melendez said he didn't have any statistics on how many times passengers are screened because of bras. But he said, "we do everything we can to ensure that a passenger doesn't feel humiliated."

Kates said she plans to talk to her family lawyer as well as the American Civil Liberties Union and the National Organization for Women and decide how to pursue the incident.

Barry Steinhardt, the director of the American Civil Liberties Union's technology and liberty program, said Monday of federal security officials: "They can't find bombs in checked luggage, and they're essentially doing a pat-down of private parts. This is a security apparatus that is out of control."

Kates said that although she flies about once a month, the only other time her bra has set off alarms in an airport was while she was being "wanded" in Cedar Rapids, Iowa. When she explained to the security agent that the wand was picking up the metal in her bra, she said, that was the end of the matter and she was allowed to go on her way.