'A Great Deal Of Arrogance'

Almost seven years later, Joan Piper still takes calls and receives letters about her daughter's death, and still believes her death is part of a pattern that may have resurfaced with a U.S. submarine off the coast of Hawaii, CBS News Correspondent Byron Pitts reports.

"Every time there's a military incident like this," Piper said of the accident involving the USS Greeneville, "you begin to collect them mentally. You compare them."

In 1994, Joan's daughter, Air Force Lt. Laura Piper, was killed. Her Black Hawk helicopter was shot down over Iraq — not by an enemy, but by two U.S. F-15 fighter jets. The military ruled it an accident.

"I refuse to call it an accident," Piper said.

In her book, Chain Of Events, Piper claims that not only was no one ever held responsible for her daughter's death, but that the military did everything in its power to hide the truth.

Her husband, retired Air Force Col. Dan Piper, agrees, saying that the military was being dishonest. Others close to the Black Hawk investigation agree with the Pipers. They agree there is a pattern of damage control and a lack of accountability.

One who believes there is a significant lack of accountability is Eric Thorson. He was chief investigator for the U.S. Senate during the Black Hawk inquiry, in which military officers were subpoenaed.

"Basically they told the United States Senate to go to hell. They would not appear," Thorson said.

Thorson said the Pentagon has stonewalled other investigators, including those working to determine what caused the deaths of 23 Marines killed aboard Osprey helicopters; an accident where a gondola cable was sheared by a U.S. fighter jet, killing 20 civilians; and the Greeneville mishap.

"I think there's a great deal of arrogance, and (having been) working in the Pentagon for a number of years at that level, I think you see that pretty clearly," Thorson said.

But retired Army Col. Larry Wortzel believes the military can investigate, and — when warranted — punish its own.

"Each of the service secretaries and the Secretary of Defense have civilian advisory boards already, so I think the institutions are in place," Wortzel said.

Thorson disagrees.

"Effective oversight is absolutely necessary because it keeps happening. It doesn't stop," Thorson said.

There are other, more intangible reasons oversight is necessary, Piper said.

"When you lose a family member in the service of this country, you have given you're most valuable possession. The military owes you more than a 21-gun salute and the flag that's on the coffin," said Piper.

We are owed the truth, Piper says, in accidents past and present.