Speaking to a crowd at Chicago O’Hare International Airport this morning, the president said the Sept. 11 terrorist attacks should not keep Americans from taking to the skies.

Mr. Bush appealed to the nation to “get on the airlines, get about the business of America.”

“Together, the government and the private sector will make flying a way of life again in America,” the president said. “This nation will not live in fear.”

Under the new proposal, the federal government would be put in charge of passenger and bag screening, making security standards tougher and more consistent around the country.

The federal government would also allocate funds for National Guard troops to be placed at airport inspection points and for airports needing dramatic improvement to meet the higher safety standards.

The president said new security measures would also dramatically increase the number of plainclothes federal marshals on airplanes, give $500 million to developing enhanced cockpit security and enable air traffic controllers to take over a distressed aircraft and land it by remote control.

Since the four airline hijackings started the deadliest terrorist attack in history, the airline industry has been reeling. Despite last week’s $15 billion federal aid package to provide relief, nearly one hundred thousand airline employees have been laid off.

In Washington, Defense Secretary Donald Rumsfeld outlined new defense department regulations in response to the attacks. Rumsfeld said two Air Force generals have been authorized to order the military to shoot down any passenger plane that appears to threatening U.S. cities.

Maj. Gen. Larry K. Arnold at Tyndall Air Force Base, Fla., would have authority to order the shoot-down of a threatening commercial flight over the 48 contiguous states. Lt. Gen. Norton A. Schwartz at Elmendorf Air Force Base, Alaska, would have authority for Alaska.

Only in the most extraordinary circumstances could the two generals order the shoot-downs without first consulting with the president, the defense secretary, or other high-level official, Rumsfeld said.

“It would have to be an extraordinary life-or-death circumstance when an attack was just seconds away before this order could be carried out,” said Michael Perini, director of public affairs for the North American Aerospace Defense Command.

White House spokesman Ari Fleischer said the number of commercial flights each day has returned to near normal, now at about 5,500, compared with the maximum before the attacks of 6,500. Still, only a small fraction of seats are filled.