As U.S.-led ground forces advance toward Baghdad, U.S. Army Chinook and Black Hawk helicopters are being called on to support various missions inside Iraq.

Flight operation offices for the units within the 12th Aviation Brigade are operating 24-hours a day, ready to respond to the needs of U.S. military commanders in the field.

Captain Guy Bass, flight operations officer for Bravo159 CH-47 Chinook company, says the pilots in his unit can get the 14,000 kilogram, double-rotor helicopters fully loaded and in the air in less than 90 minutes. "We're looking at anything from combat support to combat service support," he said. "We, at CH-47, span the whole spectrum of aviation support.

Among the several possible assignments for the Chinooks on Saturday are "sensitive site exploitation" missions.

If U.S. Special Forces hunting for evidence of nuclear, biological, or chemical weapons in Iraq do come across a suspicious site, experts will be immediately flown by Chinook helicopters to the location to investigate.

Another mission could involve transporting captured Iraqi troops to detention areas. Early Saturday morning, forces with the U.S. Army's Third Infantry Division captured a half-dozen Iraqi soldiers after a firefight deep inside the country. Thousands more were reportedly taken prisoner overnight in southern Iraq, after a battle with advancing U.S. Army troops.

Medical teams using specially equipped Black Hawk helicopters are also on standby to respond to any U.S. Army troop casualties. Since the war began on Thursday, there have been no known Army casualties. But two U.S. marines have been killed in combat, and eight British commandos and four U.S. Marines died in a helicopter crash Friday that appears to have been an accident. On Saturday, two Royal Navy helicopters collided over international waters in the Gulf, killing all seven crew members. British military officials say the crash was not the result of enemy fire.

It is not known how many troop casualties Iraq has suffered.