An air navigation map produced by the Defense Department that was used by the crew of a Marine Corps jet that hit a ski lift in northern Italy 11 days ago, killing 20 people, does not show the ski lift, lawyers for the plane's crew said Saturday.

They also said that information from a surveillance plane that had tracked the jet shows that it was on its authorized course.The ski lift was not on the map because its towers are not tall enough to merit inclusion, according to Defense Department officials in Washington.

The American military has acknowledged that the plane, a Marine EA-6B Prowler, was flying below the approved altitude of 2,000 feet when it sheared the lift's cables on a training flight through the Italian Alps on Feb. 3. The lift stretches nearly 16,000 feet from the ski resort of Cavalese, where the accident occurred, to the top of Mount Cermis, to the south.

Antonio Malattia, a lawyer for the pilot and his three crew members, said an American map used to brief the crew before the flight did not show the lift. The crew carried a copy of the map on their flight.

Mark Schultz, of the National Imagery and Mapping Agency, which produced the map, said towers need not be shown unless they reach approximately 100 feet. The lift's tower atop Mount Cermis is about 65 feet high, and an intermediate tower halfway up the mountain from Cavalese is about 46 feet.

Schultz, associate director for geospatial imagery at the agency, formerly known as the Defense Mapping Agency, said the cable may be higher above the ground than the towers that support it because the cable crosses a valley. But he added that "without putting surveyors on the ground to look at features like that, we would have no way of knowing what the height was."

The American air navigation map, known as a tactical pilotage map, was updated in 1992, according to the head of the mapping agency, Rear Adm. Joseph Dantone Jr.

Another map, called a joint operational graphic chart, produced according to specifications set by the Department of Defense and NATO, was issued in 1996, but it does not show the ski lift either.

Malattia could not say exactly which American maps the crew had used or when they had been issued.

Last week, members of the Italian Parliament were shown a map provided by the Italian military air traffic control center that approved the flight. It showed the plane's authorized course, and the ski lift was clearly marked.

But Beniamino Andreatta, the Italian defense minister, said the Italian air force maps had apparently not been used. The accident would not have occurred, Andreatta told Parliament, "if our maps had been effectively distributed to our NATO allies."

When a pilot flies a low-altitude training mission, Dantone said, "the first couple or three goes, he'd put a lot of gravy into it, fly higher than the minimum required, to really have a close look."

Investigators have said the flight that caused the accident was the first over Cavalese by the plane's Marine pilot, Capt. Richard Ashby.

The Italian government says the plane, which returned safely to Aviano Air Base, east of Cavalese, flew off course and below authorized altitudes. American and Italian officials are investigating the case.