DC plane crash updates: 55 victims recovered and positively identified

The NTSB has said their preliminary report into what caused the midair crash between a passenger plane and Black Hawk helicopter over the Potomac River on Wednesday night will take approximately 30 days and that it will take "a year or more" to get a final probable cause.

Todd Inman, a member of the National Transportation Safety Board, appeared on "Good Morning America" on Friday, saying that the NTSB "will be on scene here doing all the recovery of the perishable evidence we need for as long as it takes."

"The preliminary report, we believe, will be out in 30 days but in case of these major investigations, it will take a year, if not more, for us to come to a final probable cause," Inman continued. "The most important thing is, the work doesn't just end then. We make recommendations so that we don't have tragedies like this again in the future."

Inman said that the voice recorder and the data recorder have been recovered from the plane and the NTSB has started the process of extracting data.

"The data recorder itself has thousands of data points and they all have to be synchronized against a lot of other things that happened in the plane," Inman said. "The voice recorders have to be what is called 'auditioned' among a number of people so that there's complete agreement of how the transcript will come out. We also look for ancillary noises. Maybe a boom or thud or crack or something in the cockpit. Those things are going on concurrently, along with the fact we have several hundred people in the field looking at every other aspect of this investigation."

Inman also said that it is way too early to make any conclusions about what exactly caused the crash.

"The only conclusion I know is last night we met with several hundred family members who lost their loved ones in the Potomac," he said. "We don't need that to happen anymore. We're going to work. We're going to continue. We're going find out what happened and we're going try to stop it from happening again."

The U.S. Coast Guard shared photos of the multi-agency recovery operation in the Potomac River following Wednesday's deadly collision.

The agency said boat crews from Washington, Curtis Bay, Annapolis, Oxford, Crisfield and the Coast Guard Cutter Sailfish were responding on Thursday.

The National Transportation Safety Board said the cockpit voice recorder and flight data recorder from the American Airlines jet that collided with the Black Hawk helicopter Wednesday have been recovered from the wreckage in the Potomac River and are now at the NTSB labs for evaluation.

The runway American Airlines flight 5342 was headed towards before the deadly midair collision on Wednesday will be closed for the next week, according to a notice sent to pilots obtained by ABC News.

Runway 33 at DCA will be closed until Feb. 7, the notice said.