Voice Recorder Found At NSW Crash Site May Reveal US Firefighters' Final Words

Investigators have found a voice recorder that may have captured the final words of three Americans, who were killed when their firefighting plane crashed in southern NSW.

The large aerial water tanker was swallowed by flames after crashing in the Snowy Mountains region while battling bush fires on Thursday afternoon.

Captain Ian McBeth, first officer Paul Clyde Hudson and flight engineer Rick DeMorgan Jr were killed in the crash.

Three US firefighters were killed battling fires when their waterbomber crashed in southern NSW. Image: Facebook

Australian Transport Safety Bureau boss Greg Hood said investigators found the cockpit voice recorder while searching the plane's charred wreckage on Saturday.

It was not clear whether the recording would shed light on the cause of the crash, Hood told reporters near the crash site on Saturday.

"The cockpit voice recorder might be very useful, or it might not be. It depends on what was said," Hood said.

The Australian Transport Safety Bureau has partnered with the Bureau of Meteorology to determine the cause of the crash.

They will work to “specifically to look at the temperature, wind direction and speed, and the impact that might have had on the aircraft”

The ATSB will also interview several witnesses to help piece together the sequence of events in the lead up to the crash.

Hood would not speculate on a possible cause, saying the process could take over one week.

"I know it's very frustrating and people want immediate answers," he said on Friday.

"We will be very focused on firstly, gathering evidence and then conducting analysis so that if we do have any early learnings for people, we will broadcast those quickly."