CHARLESTON, W.Va. -- Inquiries into what went wrong at the Upper Big Branch Mine causing the deadly April 5 explosion should be conducted in full public view, for a number of reasons.

The U.S. Mine Safety Administration tends to keep such investigations carefully veiled. But MSHA's own record in policing safety violations at the Raleigh County mine is bound to come into question. Secretive hearings only obscure from the public any deficiencies in the operation of the public's agency responsible for mine safety.

Closed-door meetings can easily become an invitation-only club stacked toward company lawyers, and even lawyers hired by the company on behalf of workers.

In closed sessions, workers can more easily be intimidated out of giving thorough testimony on safety problems if they fear they and their relatives will have trouble finding work in the future, or collecting rightful benefits.

In addition, if MSHA schedules public hearings, the law gives the agency more power to make Massey Energy, owner of the subsidiary that operated the mine, turn over documents and answer questions.

Gov. Joe Manchin's special investigator, Davitt McAteer, a former MSHA chief, has said his state inquiry will be public. He held such an open hearing after the Sago disaster. It proved useful, but was far from ideal. MSHA and the company chose their own witnesses, and interviews were still secret.

Twenty-nine men died in the April 5 explosion and another two were injured. Hundreds of rescue and recovery workers then risked their own lives around the clock for a week, going in and out of the mine as conditions allowed. It was America's worst mine disaster in 40 years.

It is clear that something was wrong at Upper Big Branch. Operated properly, coal mines do not explode.

Apologists for workplace deaths often fall back on a sad shrug. "What can you do?" they ask. "Coal mining is inherently dangerous."

True. It is dangerous. But the United States, and certainly West Virginia, has never tried mining by fully following the rules based on what has been learned from two centuries of experience and death.

Concealed, guarded investigations don't seem to help much. This time, President Obama, who has spoken strongly for worker safety in mines, should make the federal investigation transparent to the public.