When Mikhail Gorbachev heads for Camp David today, he will be doing something that American presidents since Dwight D. Eisenhower have done: calling on the Marine Corps to battle Washington's traffic.

Since 1957 the Marine Corps has been helping Washington VIPs and their families avoid the woes of urban traffic in Washington and in cities around the world by whisking them literally doorstep-to-doorstep in a fleet of white-topped helicopters.

A Marine spokesman said it is likely that President and Mrs. Bush and the Gorbachevs will depart the South Lawn this morning in one of the Corps' older, familiar Sikorsky VH-3D helicopters, the workhorse of the White House chopper fleet for most of the past decade.

The flight will take about 30 minutes, a decided improvement over getting there by highway, no matter how impressive the motorcade.

The spokesman, one of the few government sources willing to offer any details about the helicopter operation, said it is unlikely that Gorbachev and his wife, Raisa, will get to ride in one of the White House's newest, most expensive helicopters, the $10.6 million Sikorsky VH-60, which the Marine Corps purchased last year.

Nine of the new helicopters are now part of the special fleet, but both new and old models, "executive" versions of military aircraft, are equipped with the latest communications and navigation gear. They are flown by the elite of Marine Corps' helicopter pilots, members of Marine Helicopter Squadron 1 based at the Quantico Marine Base south of Washington. Details about the unit -- designated HMX-1 -- are sparse. A White House press officer referred calls to the Pentagon press office. Officials there referred calls to Marine Corps headquarters, which referred calls to Quantico. Officials there referred calls to the White House Military Office, which, in turn, referred calls to the White House press office.

What is known about the helicopter unit largely has come from outside sources and former White House officials. William Tuttle, a spokesman for Sikorsky Aircraft in Stratford, Conn., describes the nine new helicopters as "simply much more helicopter" than the 10-passenger VH-3D. The new machine is a version of the Army's Black Hawk helicopter and is popular at the White House because, unlike the older VH-3D, it can be quickly broken down and placed aboard cargo aircraft for out-of-town trips.

When the president or vice president is aboard, the helicopters are known by their radio call sign of "Marine One" or "Marine Two," as with Air Force One and Two, the presidential and vice presidential jets. The VIP helicopters come in two varieties, with "white tops" for senior administration officials and "green tops," helicopters painted in the Corps' olive green for the media and less senior officials.