SUMTER - Dressed in jeans and sweatshirts, the group of mostly 20-somethings looked like they were headed Tuesday to Florida for spring break.

Instead, the approximately 250 men and women at Shaw Air Force Base were dressed casually for a 17-hour flight to somewhere in the Persian Gulf region.

The airmen, all members of the 77th Fighter Squadron of Shaw's 20th Fighter Wing, are joining the U.S. buildup for a possible war with Iraq.

Also leaving Tuesday were some of the command personnel of the Ninth Air Force, which is based at Shaw.

Shaw already has one squadron - the 55th - deployed. Its pilots and personnel are at Incirlik Air Force Base in Turkey, supporting Operation Northern Watch, a policing action over northern Iraq. The 55th left in early December on a 90-day assignment and is due back in March.

The 77th squadron's departure leaves just two other fighter squadrons, the 78th and 79th, at Shaw.

Although the 77th has deployed routinely to the gulf area in recent years - flying missions over northern or southern Iraq to enforce the United Nations' "no-fly zones" - nothing seemed routine Tuesday.

"This is a much more tense situation," said Airman 1st Class Adrian Radvizee, 24, who's being deployed for the second time.

"There's a lot more uncertainty," said Radvizee, a native of Angeles City in the Philippines.

Wing commander Col. Bill Rew acknowledged the tension, but added everyone knew a day like Tuesday might come during their Air Force careers.

"It's obviously a different situation," said Rew, 45, who'll be leaving next week to join the U.S. Central Command staff in Qatar. "We're just going to go in, get the job done and come back home."

The squadron's deployment is in two phases.

Support personnel - including mechanics, munitions handlers, avionics technicians and some pilots - left Tuesday.

Fifteen of the squadron's 18 F-16 attack jets are scheduled to leave later, base officials said, declining to say just when.

Just hours before their flight, squadron members were waiting in line at the base's processing center.

All the goodbyes to family and friends were completed by the time airmen walked through the door about 1 p.m.

Airmen were allowed to carry on two bags - one of them a sealed "chem bag" containing gear they'll need if they're exposed to chemical weapons.

The bag included a chemical suit, gloves and boots. Airmen carried their own gas masks, which are personally fitted, and Kevlar helmets.

The second bag contained personal items the airmen wanted to bring. Some brought along an extra pillow and blanket to keep them comfortable on the long flight.

The processing center included stops for smallpox shots. All deployed airmen have to get the shot unless their family health history indicates they could suffer an adverse reaction, officials said.

Legal and financial assistance also was offered in the processing center, as well as some spiritual aid.

Capt. Craig Chandler, a chaplain at the base, offered Bibles, Jewish prayer books and literature on Islam to airmen. "In tough times, having something spiritual to read can be a good thing."

Since the Shaw squadron's potential deployment was announced in mid-January, the unit has conducted training missions day and night to polish skills and check out equipment before heading to the Persian Gulf.

Capt. Scott "Beave" Sieting, 26, of Detroit, said he'll be relying on the training he has received during his four years in the Air Force to help him deal with whatever he faces in the Persian Gulf region.

"I'm excited," said Sieting, an F-16 pilot. "I want to get to where I'm going."

Sieting is the second member of his family to serve in the gulf. An older sister, who was an Air Force nurse, served during Desert Storm.

Staff Sgt. Danny Dubois, 29, of Shreveport, La., is a veteran of three previous deployments in his nine-year Air Force career. Leaving never gets easier, said Dubois, who's married and the father of two daughters, ages 7 and 4, and a son, 8 months old .

His family will remain in Sumter and wait for his return, whenever that will be, Dubois said.

The Air Force originally said Jan. 13 that the squadron would be deployed for 90 days, but the return date is now open-ended "due to world conditions," a spokesman said.

While he's proud to serve his country, Dubois said he has concerns - mostly about what he'll miss while he's away.

"I'm wondering how big my boy will be when I get back," Dubois said. "My older daughter is in the second grade, so she'll probably be out of school when I get back. Then she'll be playing tee ball."

Dubois reflected on previous deployments, primarily peace-keeping missions. This trip is much different, he said.

"This is the real deal."