SAN DIEGO (CBS 8) - We've been following the NTSB on Twitter, they're already releasing information from the flight recorders.

For instance, one tweet said the throttles were advanced a few seconds before impact.

They still have a lot of information to go through. So, exactly what goes into an investigation like this? News 8 asked a local expert.

Witnesses say the Asiana aircraft came in too low when it was trying to land. Former FAA accident investigator Robert Griscom says the wreckage offers some clues.

"When I saw the tail broken off, I associate that with a high deck angle. Or a high angle of attack."

Meaning, as it came in, the nose was pointing up, causing the tail to hit the ground first. The question now is what caused this.

Griscom says it's too early to start speculating but the data recorder the NTSB now has will give them some insight into the mechanics of the plane.

"It could say that the engines were not developing full power, that the throttles were pushed all the way forward and that gives people clues, investigators something to work with."

The other important piece is the cockpit recorder. That will give investigators a look at the pilots and if they may have played a role in the crash.

"When did they realize they were too low. Was it way back out here, and they couldn't do anything about it. Or was it when they got too close and it was too late to do anything about it."

Asiana Airlines says NTSB has confirmed that an important guidance system at the airport called a guide slope was turned off. It's an instrument that helps planes land.

But Griscom says it wouldn't have made a difference yesterday.

"It's used in instrument landing conditions when you can't see the runway...until the last moment. And it's not at all important in this case. They didn't need it."

Pieces of what the NTSB may be released in the near future but Griscom says the whole investigation could take well over a year.

Earlier, Asiana Airlines said mechanical failure was unlikely. News 8 spoke to the NTSB Sunday and they say everything is still on the table.