An American Airlines pilot who safely landed a passenger plane at Denver International Airport on Thursday initially did not seem overly concerned over engine vibrations detected after the plane departed Colorado Springs bound for Dallas.

An air traffic control audio recording released on Friday indicated the female pilot remained calm and in control, as she brought the diverted Boeing 737-800 aircraft to DIA.

In a conversation between the pilot and air traffic control published by Live ATC, the controller asked the pilot to confirm that the mid-air engine that was reported earlier was “not an emergency.”

“Nah, we just have a high engine vibration, so we are cruising slower than normal,” the pilot responded.

Working to assist the pilot, the controller offered AAL1006 a more expeditious arrival into Denver International Airport.

The plane was then handed off to Denver approach, where the pilot was instructed to land on runway 16R.

“Do you need any extra assistance upon arrival — certain speed on the arrival or final, or certain length on final,” the controller asked.

“No, actually, we could definitely maintain approach pace. We just can’t do climbs because we’re having a high engine vibe, so we’ve got it pulled back,” the pilot said.

A controller then cleared the aircraft to land.

The plane landed at 5:55 p.m., according to FlightAware.

Shortly after the aircraft lands, a man’s voice on the same radio frequency can be heard yelling, “Mayday, Mayday, Mayday! Mayday!”

“Engine fire!”

One of the plane’s engines had burst into flames, prompting an emergency evacuation.

AAL1006 departed Colorado Springs Municipal Airport (KCOS) to the south at approximately 4:32 p.m., according to data collected by flight tracker ADS-B Exchange.

Over the next 30 minutes, the aircraft climbed to an altitude of 16,425 feet and attained an airspeed of 359 knots.

By 5:12 p.m., AAL1006 was more than 170 miles southeast of Colorado Springs when the aircraft turned back to the northeast to land in Denver.

Officials from the Federal Aviation Administration confirmed that one of the aircraft’s engines caught fire while taxiing, prompting 172 passengers and six crew members to evacuate using emergency slides.

Several social media video posts showed smoke pouring from the plane as passengers stood on the wing.

Airport ground crews quickly extinguished the flames, officials said.

An airport spokesperson confirmed 12 passengers were transported to local hospitals with “minor injuries.”

The FAA is investigating the incident.