Debra Burlingame and April Gallop sat unflinchingly in the audience yesterday as one witness after another described the overwhelming confusion that ruled military command centers and air traffic control rooms on the morning of Sept. 11, 2001.

The hijackers cost Burlingame a brother, Charles, who was captain of American Airlines Flight 77, which crashed into the Pentagon. Gallop, an Army administrator who had just returned from maternity leave, was seriously injured in that attack, as was the infant son she had brought to her Pentagon office that morning.

But their reactions to the testimony before the bipartisan National Commission on Terrorist Attacks Upon the United States differed vastly.

When the hearing was over, Burlingame approached a Navy witness to say something she knew he would not hear from other 9/11 family members in attendance.

"Thank you," she told Capt. Charles J. Leidig Jr., who was in charge of the National Military Command Center, located in the Pentagon, on Sept. 11. "I know you did all you could."

Burlingame said she does not blame anyone in the U.S. government for the failures that allowed the 19 hijackers to reach their targets unimpeded.

"I defend the FAA, though I think they were the weak link," she said. "But I don't think anyone could have anticipated this."

Gallop, who leans on a cane to balance her misaligned spine and hip from injuries she suffered when she was buried under four floors of debris, believes somebody in authority needs to shoulder some blame for failing to track and intercept the hostile aircraft.

"Their failure to do their job caused the injury and death of people," she said. "I know it wasn't intentional. It was negligent. There's an invisible wound in my heart that can only be closed with truth, and by someone accepting responsibility."

Several dozen surviving family members filled the front and center rows of the auditorium where the 9/11 commission held its final public hearing yesterday. Most lost relatives in the collapsed twin towers of New York's World Trade Center. Burlingame and Gallop were among the few connected to the plane that struck the Pentagon.

Many family members in the audience seemed to share Gallop's perception. They shook their heads in disbelief over audiotapes in which Federal Aviation Administration and North American Aerospace Defense Command officials kept mixing up the numbers and paths of hijacked planes. Several audibly snorted at a characterization of President Bush's desire to project "strength and calm" in a classroom of second-graders when told America was under attack.

Burlingame said she was not troubled by testimony in which officials retraced what they knew -- and when they knew it -- to explain why they had not shot down the planes before they hit their targets. For example, one witness said that during the Cold War, military pilots practiced dropping tail hooks that could slice through a cockpit window and "ram" a hostile plane to earth. But those practices were for planes far different from the commercial aircraft that were hijacked on Sept. 11.

She considers it a pipe dream to think the planes could have been shot down short of Washington and Manhattan.

"After 21/2 years, my family has already contemplated so many scenarios, including that one," said Burlingame, a former flight attendant whose brother had been a Navy fighter pilot.

"But they couldn't have done it. They scrambled the planes, but they didn't know where to scramble them to. They're not going to send out F-16s armed with weapons to willingly target an unmarked, unidentified plane with civilian passengers carrying 66,000 pounds of fuel over suburban Maryland. Maybe they would have killed 1,000 or 2,000 others. They could have hit Crystal City. Who would they blame then?"

Burlingame said she found it frustrating to hear commissioners lob accusatory questions at military and aviation officials.

"They seem to be very focused on blaming people as opposed to looking for fixes," she said. "The people who are solely responsible are the 19 men who boarded the planes and their sponsors. Our country was not prepared for the kind of assault they made. But don't beat up on the FAA for mistakes. When a patient is on the operating table is not the time to decide to reorganize the hospital."

As Gallop listened to the testimony, however, she concluded that the level of confusion caused by the simultaneous attacks should not have been as high as it was. She was troubled by military officials who characterized their domestic role as defending the country against an attack from overseas, not from within. According to testimony, FAA officials were sometimes uncertain over how much authority they had. And after Vice President Cheney authorized the military to shoot down hijacked aircraft, the orders were never passed on to pilots.

"No one seems to know whose job it was to do what," said Gallop, who has taken a medical retirement from the Army. "It blows my mind. The most catastrophic day in U.S. history, and they didn't know what their responsibilities were."

The errors were all human, said Gallop, citing testimony by the chief of U.S. air defenses that fighter jets could have stopped the hijacked airliners if only the FAA had alerted the military sooner.

"He said if everything were perfect, they could have prevented the entire day," Gallop said. "Well, it's not if everything were perfect. If everybody did their job that day, it wouldn't have happened in the manner that it did."

Annie MacRae of New York City lost her sister, Cat, in the attacks on the World Trade Center. Family members of those killed and survivors of the terrorist attacks watch the Sept. 11 commission's final day of hearings from a special seating area.