OVER SAUDI ARABIA -- By the time the lights of Dhahran were visible in the distance, Maj. Louis C. Cusimano had been awake for more than 14 hours, flying for eight and not expecting to see a bed for another 10.

His back hurt. His neck was stiff. His eyes were sore. His posterior ached.

"This used to be fun when I was 25," said the 44-year-old Federal Aviation Administration desk jockey from Davidsonville.

At 37,000 feet, the Air Force reservists who had begun this supply mission at Andrews Air Force Base outside Washington two days earlier saw Saddam Hussein as the least of their worries.

"The real risk," Capt. Sam Szvetecz said before takeoff, "is the fatigue."

They call it the "Sandbox Express." For seven weeks, crews from Andrews like this one have endured a grueling, round-the-clock sched- ule ferrying thousands of tons of cargo and tens of thousands of troops to bases in Saudi Arabia and nearby countries.

The job is not glamorous, not adventurous. But military officials say the work of reservists like those from the 756th Airlift Squadron from Andrews has been critical to the rapid deployment of Operation Desert Shield, the largest U.S. airlift since the Berlin Airlift of 1948-49.

During a recent weeklong mission, the weary crew from Andrews coped with ground crews who tried to load too much cargo, command posts confused about their destination and three-hour quests for an empty bed at the end of a 24-hour mission.

The call came shortly before midnight on a Friday. Five members of the 756th learned their flight would be leaving Andrews at 3:15 a.m.

Their camouflage-painted C-141B Starlifter sits low to the ground with droopy wings. The original C-141 began flying in 1965 and served extensively in Vietnam. The updated B version was delivered by Lockheed-Georgia Co. in 1979. More than half a football field in length and in wingspan, the plane can carry about 200 troops or 70,605 pounds of cargo.

The Andrews crew already had aboard about two dozen support soldiers who had left Louisiana earlier in the evening with a different crew. Some of them were recreation officers who intended to build the first three-hole "pitch and putt" golf course in Saudi Arabia for the troops, with plywood, artificial turf and plenty of sand traps.

The C-141 isn't built for comfort. There are no windows, no regular seats, no in-flight movies and no flight attendants. Passengers sit on fold-down canvas benches with webbed backing, shiver in the cold of 37,000 feet and wear earplugs to block the roar of the engines.

The crew comes from many different backgrounds, bound by their love of flying.

The congenial Cusimano flew similar missions into Vietnam as an Air Force pilot before joining the reserves in 1972. He had been growing a little restless in his FAA desk job lately, he said. The past month has reminded him that piloting a desk isn't so bad.

Lt. Kirk E. Chestnut, 27, the copilot from Fredericksburg, Va., is the son of a commercial pilot whose Tom Cruise sunglasses make him look like he just walked off the set of "Top Gun." For two years, he was a "reserve bum," flying whatever missions he could get for the 756th. In May he got a job at American Airlines, but flew just two flights before being called back to duty.

Tech. Sgt. Donald S. Marshall, 45, a grizzled flight engineer and retired D.C. firefighter who lives in Shadyside, said he missed flying so much he rejoined the reserves in 1987 after an absence of nearly two decades. He conceded that his absences have placed a strain on his marriage and family.

Senior Master Sgt. Franklin P. Laning, a 42-year-old engineer from Waldorf, said he has had more time to spend with the reserve unit since his wife died three years ago. Laning, who works full-time coordinating flights, was on his first trip to the Middle East.

Master Sgt. Arthur D. Guyton Sr., 39, the loadmaster who lives in Baltimore, left full-time status with the reserve squadron a few years ago to pursue a lifelong desire: riding the rails as an Amtrak conductor. He was scheduled to leave on a train trip when he got the call to report to Andrews.

From Andrews, the crew flew eight hours to Rhein-Main Air Base outside Frankfurt, West Germany, which with bases in Spain and others in Germany serves as an airlift "hub." There crews eat and rest between flights "down range," as they call the gulf area. They usually pick up a third pilot for extended journeys.

It's easy to lose all sense of time and day on these missions.

Crews may leave at 3 in the morning or 5 in the afternoon. There is no daily routine because each "day" can last anywhere from 24 to 36 hours. The rules are: Eat when there's food in front of you and sleep when you can find a bed, cot, sleeping bag or a spot on the floor.

On this trip, the crew from Andrews was sent down range twice, once to a base in Saudi Arabia carrying tents, cots and medical supplies and the second time to an isolated, single-runway base in the United Arab Emirates carrying a load of missiles.

The plane cruises at three-quarters of the speed of sound and its automatic pilot does most of the flying. The pilots constantly check maps and coordinates, communicate with air traffic controllers in countries from Greece to Bahrain and feed information to a computer.

They consider their work almost routine, brushing off any suggestion of possible danger. Only once during the week, when they were preparing to fly to the United Arab Emirates, did anyone raise the specter of being shot down.

Although never under fire from Iraqis, the crew sometimes was victimized by American disorganization.

On the first trip, they arrived at the airplane to find no cargo aboard. "Clueless," Cusimano said, shaking his head. It was a word he was to use often during the week.

Eventually, the ground crew located some cargo, then tried to persuade Cusimano to accept 61,000 pounds even though the plane was restricted to 43,000 pounds.

On a second trip, out of Ramstein Air Base, a two-hour bus ride from Rhein-Main, they waited two hours on the runway for box lunches to be delivered.

At Ramstein, too, the ground crew tried to persuade Cusimano to accept more than 50,000 pounds of missiles, but he refused because Ramstein's short runway would have made a takeoff risky.

"We'd be burning till the next Fourth of July" in a crash, Laning said.

"They kept saying 'blanket waiver,' " said an irritated Marshall. "Well, I said, 'You aren't putting no blanket on me at the end of the runway -- or what's left of me.' "

Like many of the military men and women involved in this operation, they had their share of complaints -- about the ground crews and the housing arrangements, about the uncertainty of when their duty would end and how it was interfering with their family plans. Yet, for all the griping, the Andrews crew members all said they enjoy flying and don't intend to quit.

"Every time I start feeling bad about this . . . I think about the poor bastards in the desert," Cusimano said.

"Yeah," Chestnut agreed. "We really don't have much to complain about, do we?"