by Erin Jones | CBS 11

DFW AIRPORT (CBSDFW.COM) – We’re hearing the first unscripted moment between pilots who fly the 737 max planes – and officials for the company that creates them.

In it, the pilots Boeing about the new features that investigators believe are factors in two deadly crashes that killed hundreds of people.

CBS News obtaining this exclusive audio from the American Airlines Pilot’s Union.

After investigators said a system on the 737 planes was not safe – those pilots demanded quick action from Boeing.

“We’re the last line of defense to being in that smoking hole. And we need the knowledge,” said a pilot on the recording.

In this recording – American Airlines 737 pilots demanding answers less than a month after Lion Air Flight 610 went down off the coast of Indonesia killing 189 people.

Investigators later reporting a faulty sensor in the plane triggered it’s MCAS anti-stall system that repeatedly pushed the nose down.

“These guys didn’t even know the damn system was on the airplane — nor did anybody else,” said a pilot.

An unidentified Boeing official – who did not know he was be being recorded – claimed this was a once in a lifetime scenario. He said he didn’t know if knowing the system would have changed the outcome.

“In a million miles, you’re going to maybe fly this airplane, maybe once you’re going to see this, ever. So we try not to overload the crews with information that’s unnecessary,” the Boeing official said.

Boeing told the pilots they’d make software changes in as little as six weeks, but didn’t want to rush it.

Four months later – the second 737 Max crash occurred – killing 157 people on board an Ethiopian Airlines plane. The fix was still in development. The plane was grounded worldwide.

Boeing officials have reported they’re working to get the plane safely back in the air. The pilots say they’ll never fly an unsafe aircraft.