Col. Galen Jackman, commander of the Ranger Training Brigade at Eglin, was quoted by the Associated Press as saying yesterday that the water temperature was 52 degrees, just above the 50-degree threshold set in 1977 after two soldiers died from hypothermia during Ranger training. The air temperature was in the 60's after several days of chilly weather.

"What was unusual," Sergeant Ray said, "was the water was deeper than normal. It was chest high. Normally, they expect knee deep, maybe waist high. But they've had a lot of rain down there."

About 5:30 P.M., one of the four instructors assigned to each training unit, noticed that one of the soldiers was showing signs of hypothermia. What those signs were, the sergeant said, she did not know.

Hypothermia, a drop in the body's internal temperature below 95 degrees Fahrenheit, results when the body loses heat faster than it can be replaced. Conditions need not be extremely cold for hypothermia to set in. It can strike a person who is exposed to a prolonged chill of 60 or 65 degrees. Signs of hypothermia sometimes include confusion and lack of coordination. Victims often shiver uncontrollably.

After discovering the soldier with hypothermia, the instructor called in a medical evacuation helicopter, and by the time it arrived 15 minutes later, the instructors decided to evacuate two more soldiers. They were taken to the clinic base, where they were treated and released.

Two hours later, two more soldiers began showing signs of hypothermia and the helicopter was called back. It hovered over the swamp and the soldiers were hoisted inside.

By then the swamp had been shrouded in dense fog and two more soldiers had to be evacuated over land. Their trip to the ambulance took 40 minutes, and two Ranger instructors administered cardiopulmonary resuscitation to them on the way. Of the last four soldiers evacuated, only one survived.