TIKRIT, Iraq — The call crackles from the radio at 1:01 p.m., interrupting the National Guardsmen from New Hampshire and Maryland as they munch on individually packed bowls of cereal and joke about their lives back home: "Smuggler 72, Smuggler 72, you have an urgent medevac."

The call starts the clock ticking for the helicopter-borne medics on a mission that is all about speed: In this case, getting to an Iraqi soldier wounded by a roadside bomb.

The four men in beige flight suits abandon their food and race from the hangar. The lead pilot and medic are briefed on the mission; the co-pilot and crew chief prepare their Black Hawk helicopter.

Within eight minutes of the call, the chopper is roaring to life and the pilots radio the control tower for permission to lift off.

Their goal is to get the wounded man to the hospital within the "golden hour" — the critical first 60 minutes that can determine whether a combat casualty lives or dies.

"If I can keep it under an hour, the chances of survival are higher," said Sgt. Matthew Miller, 37, of Pasadena, Md.

With five years' experience on an emergency ambulance and eight more years as a paramedic, Miller is the most seasoned of the unit's medics.

The 1159th Medical Evacuation Air Ambulance Company keeps three Black Hawk crews in Tikrit on standby, ready to rescue not only American troops but also Iraqi soldiers and civilian contract workers.

The calls for help come in the form of a nine-line "medevac" request. It has nine specific pieces of information the air ambulance needs to respond, from the exact location of the pickup to chances of hostile fire.

Commanders routinely paste the requirements on the windshields of Humvees to help flustered soldiers who may be under fire when they need to place the call.

Once airborne, the two pilots steer the craft low and fast, guided by a satellite-linked computer.

As the craft skims the rooftops of mud-brick houses and dodges power lines, the medic and crew chief keep an eye out for insurgents who could shoot them down.

At 1:31 p.m., pilots and crew see a thick plume of black smoke rising from a highway and signal flares farther down the road. They circle twice to assess security and decide where to land.

They know not to touch down on the blacktop in case another bomb is concealed. Instead, they land on a barren stretch off the road. Dust swirls up, momentarily blinding the crew. It is 1:35 p.m., 34 minutes after the call for help came in.

Sgt. Jon Ciley, a medic from Belmont, N.H., heads for a crowd around the injured man. He consults the medics who provided first aid, makes a quick assessment and loads the Iraqi onto a stretcher for carrying to the helicopter. The patient has shrapnel wounds to the head and thigh.

Fewer than three minutes elapse between touchdown and liftoff.

Ciley measures vital signs and sets up an IV line. The crew chief, Staff Sgt. Matthew Stohrer of Gilmanton Iron Works, N.H., holds the IV bag elevated while Ciley prepares a morphine injection.

On his radio headset, Ciley speaks to the pilots about how much time they have and which hospital to head for. They need to factor in flying time, fuel and the nature of the wounds, with different hospitals specializing in different injuries.

"Treatment in the air won't save a patient's life, but it will buy us some time," said Miller, the unit's senior medic back at the base.

Fifteen minutes after leaving the injury site, the Black Hawk approaches a combat support hospital near Tikrit. Just before landing, Ciley briefs the clinic on what to expect. A team with earmuffs unloads the stretcher and hustles the wounded man inside.

Ciley follows, relaying information he gathered at the injury site and during the flight. He reads off the heart rate and blood pressure from a strip of tape he has affixed to his knee. It is 1:53 p.m. — 52 minutes since the initial medevac call.

The patient has arrived within the golden hour. He survives his injuries.