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Jan 30 (Reuters) - More than 60 people were killed when

an American Airlines ( AAL ) regional passenger jet collided

with a U.S. Army Black Hawk helicopter on Wednesday and crashed

into the frigid Potomac River near Ronald Reagan Washington

National Airport.

Secretary of Transportation Sean Duffy said the midair collision

should not have happened, and vowed reforms to "make sure that

these mistakes do not happen again and again."

The cause of the crash is under investigation. Below are the

details:

* U.S. National Transportation Safety Board (NTSB) chair

Jennifer Homendy promised a thorough investigation, leaving no

stone unturned to find out what caused the crash.

"We are going to conduct a thorough investigation of this

entire tragedy, looking at the facts," she told a news

conference.

* The NTSB said it was too early to speculate on the cause.

"We don't know enough facts to rule in or out human or

mechanical factors," lead investigator Brice Banning said.

* The NTSB has not yet attempted to recover the airplane's

black boxes, giving priority to efforts to remove bodies of

victims, but it is confident it will be able to retrieve them.

* Civil aircraft carry two recorders, one for data and one for

cockpit voices. Those will provide vital clues on the last

moments of the jetliner flight.

* The helicopter also has a recording system that will be

read by the military or NTSB in co-operation, Banning said.

* The NTSB will set up various working groups to break the

investigation down by topic including aircraft and engine

matters, air traffic control and operations. A group focusing on

human performance will span several of those categories.

* Homendy said all investigations study humans, machines and

their environment. Safety experts say aircraft accidents are

almost invariably the result of multiple factors.

* The NTSB received air traffic control data in the early

hours of Thursday and is reviewing it, Banning said. It will

take time for the investigation to reach conclusions.

* The NTSB will interview controllers and others as part of

the investigation. They will scrutinize the aircraft and

training procedures for the Army helicopter.

* Wreckage from the incident is being stored in Hangar 7 at

the Ronald Reagan Washington National Airport.

* The NTSB said it would meet on Thursday with planemaker

MHI RJ Aviation, the U.S. Federal Aviation Administration (FAA),

American Airlines ( AAL ) and other parties to organize the

investigation.

* Canada's Bombardier designed the out-of-production

regional jet but sold the program to MHI RJ Aviation, a

subsidiary of Japan's Mitsubishi ( MSBHF ), in 2019.

* The investigation is being carried out under global rules

calling for a preliminary report within 30 days. A final report

with analysis is expected within 12-18 months.

* The purpose of such investigations is to establish the

probable cause and make recommendations to avoid more accidents.

* The NTSB does not attempt to establish blame or liability.