The 9-11 commission's findings on U.S. air-defense failures to respond swiftly to the terrorist hijackings rank among the most unsettling yet.

Military and civilian authorities since Sept. 11 have improved U.S. air defenses, but a recent air scare over New York City showed that "front-line" decision-makers still don't understand what they need to do in the face of imminent threats. This is not acceptable.

A Federal Aviation Administration operations manager told the 9-11 commission he wasn't sure he had authority to ask the military to scramble fighter jets to intercept the unidentified aircraft. Luckily, it turned out to be just a civilian aircraft on a photo shoot, but surely Sept. 11 proved we can't depend on luck.

Both commission co-chairmen, Republican Thomas H. Kean and Democrat Lee Hamilton, are skeptical that the chaotic response problems of Sept. 11 have been corrected. They have good reason to doubt.

If air-control officials are still confused over one unidentified aircraft, whether that plane is over Manhattan or Kentucky Gov. Ernie Fletcher's June 9 Washington flight that caused such panic at the Capitol, then how prepared are U.S. air defense units to handle multiple, simultaneous threats? That's what happened on Sept. 11. Al Qaida "flooded" the system, and even the dimmest terrorist cell now knows how lethally it worked. Homeland defense forces from now on need to be training and regrouping for multiple threats coming at us all at once and not necessarily from the air.

The commission's 29-page report "Improvising a Homeland Defense" doesn't paint a pretty picture. Although on Sept. 11 many air controllers and middle managers took initiative and issued timely alerts, that morning was a series of tragic communications breakdowns, slow reactions, erroneous notices and wrong-way countermoves.

The 9-11 investigators concluded: "On the morning of 9-11, the existing (FAA-NORAD) protocol was unsuited in every respect for what was about to happen. ...They struggled, under difficult circumstances, to improvise a homeland defense against an unprecedented challenge they had never encountered and never trained to meet."

"All points bulletins" on the hijackings were not issued to all air controllers. Precious minutes were wasted by FAA officials debating whether to notify the military. FAA and the North American Aerospace Defense Command (NORAD) did not have instant communications links. U.S. fighter jets were scrambled in the wrong directions. Langley fighters sent to guard Washington were 150 miles away when American Airlines Flight 77 hit the Pentagon. Orders to shoot down hijacked planes were late in coming and not relayed to fighter pilots. The FAA never requested military help to defend against United Airlines Flight 93 which was heading for Washington but crashed in Pennsylvania. In retrospect, the nation truly owes those heroic passengers a great debt.

The threat of more terrorism on U.S. soil is real, as seen this week with the indictment of a Columbus man linked to al-Qaida and suspected of plotting to blow up a mall there. Bush officials and congressional leaders need to speed the conversion of U.S.-Soviet-era air defenses to more flexible systems that can cope with multiple terrorist threats.