Carlos Bongioanni / S&S Lance Cpl. Maximilian Lopez, left, and Lance Cpl. Edward Wood use an electronic scope to adjust the receiving functions of an AN/TPS-59V3 Radar used in Afghanistan to monitor air traffic and aid in command and control. Carlos Bongioanni / S&S Lance Cpl. Maximilian Lopez inspects an AN/TPS-59V3 Radar used in Afghanistan to monitor air traffic and aid in command and control. Carlos Bongioanni / S&S Sgt. James Buchanan flips on the power inside a 20-foot long by 7-foot wide tactical air operations module used in Afghanistan to monitor air traffic and aid command and control.

MARINE CORPS AIR STATION FUTENMA, Okinawa — Human eyes need a few seconds to adjust to the darkness inside the metal box.

The lead-gray walls of the 7-by-20 tactical air operations module seem to absorb the overhead fixtures’ dim light. A narrow passageway, with sophisticated floor-to-ceiling communications racks flanking both sides, opens to the container’s back half, which is crammed with four computer consoles.

At one, the screen’s glow lit Cpl. Steven Williams’ face as he watched green radar blips flash up and fade away. No operating “outside the box” for Williams: Only within the metal module can he see the blips, each representing an object flying through a closely monitored air space.

The Marine is a tactical air traffic controller and surveillance identification director with the Futenma-based Marine Air Control Squadron 4. The computers are connected electronically to powerful, ground-based radars that “paint” the horizon with invisible radio-wave particles. The AN/TPS- 59 radar can detect anything flying within 300 miles.

Controllers such as Williams identify, classify and track all detected objects and pass the data to the theater’s command-and-control centers, giving commanders an overall “operational picture” of their air space.

Based on that information, commanders could scramble fighters to engage enemy aircraft entering the space or direct ground control intercept units to fire ground-to-air missiles to down aircraft or incoming missiles.

Tactical air traffic controllers also “deconflict” the air space toward ensuring friendly aircraft don’t collide. They help fighters, bombers and transport aircraft coordinate times and locations to meet tanker aircraft for refueling.

For more than a year, MACS-4 members have provided such services to support operations against Taliban and al-Qaida forces in Afghanistan. One detachment remains at Karshi Khanabad, Uzbekistan, but another from Kandahar Airfield — where Williams spent nine of the past 12 months — has returned to Okinawa.

Don’t expect many travel photos, though: While in Afghanistan, MACS-4 members spent their entire time within a two-mile radius of their detachment site. They never left the airfield or saw the countryside, said Capt. Mike Hicks, the detachment’s executive officer for six months.

An average workday lasted about 10 hours, including briefings and debriefings book-ending eight-hour shifts inside the ops module. The job got stressful, Hicks said, during major operations when numerous coalition aircraft were providing fire support for troops or bombing enemy mountain hideouts.

But mostly, the captain said, “monotony was the toughest hardship.”

Staying focused hour after hour, day after day for months is “mentally challenging,” acknowledged Williams.

“We’ve got very experienced people who don’t blink but twice in an eight-hour shift,” he joked.

No one joked, however, about the stakes: the mission, and troops’ lives.

“This is serious business,” Williams said. “It’s intense, especially when you think of the grunt on the ground.

“You don’t want to do any blue-on-blue stuff,” he said, referring to a 2002 incident in which two U.S. F-16 pilots bombed a Canadian unit near Kandahar, killing four and injuring eight.

For most of its deployment at Kandahar, the MACS-4 unit supplemented coverage provided by U.S. and British Airborne Warning and Control Systems aircraft.

In January, as war in Iraq loomed, most AWACS coverage over Afghanistan shifted elsewhere. After that, as to the job of providing primary coverage, said Lt. Col. Gilbert Gonzalez, who took command of MACS-4 in December, his unit “pretty much had it all.”

The Afghanistan and Uzbekistan deployments initially were a morale booster, he said, because they were outside MACS-4’s normal “area of responsibility. … We could have sat at home as spectators the entire time. Instead, we were participants.”

His troops got to help clear Taliban forces from their mountain strongholds. But among their most noteworthy accomplishments, he said, was keeping the unit’s AN/TPS-59 radar turning almost continuously for 18 months.

MACS-4 deployed to Guam two days after the Sept. 11, 2001, terrorist attacks to help defend the United States and U.S. territories. From there, many went directly to Kandahar in April 2002. Several rotations of unit members kept the radar turning for another 12 months.

Once operations in Iraq wound down, an Air Force unit replaced the Marines in Kandahar. News of the replacement came as a relief, said Gonzalez; never knowing when they were coming home was the toughest part.

“There was no end in sight,” he said. “Now we’re waiting to see when we’ll get back our guys in Uzbekistan.”

MACS-4 troops saw U.S., British, Canadian, Romanian and Jordanian units come and go, Williams said.

“We were there so long, many people were surprised to hear we were leaving. They thought we were a permanent fixture.”