(thank you AVHerald)
Not having a lot of luck with finding the audio, anyone can do some deeper searching?
A Delta Airlines Boeing 737-900, registration N830DN performing flight DL-9950 from Kansas City,MO to Atlanta,GA (USA) with 2 crew, was climbing out of Kansas City's runway 01L when the crew requested to level off and stopped the climb at 10,000 feet advising ATC they had an airspeed indicator problem, subsequently following up stating "the Captain's instruments are all bad", not working at all. The crew explained the aircraft had been parked for about 13 months due to the Covid Pandemic and they were on the first flight of the aircraft since. The first officer was pilot flying now, his instruments were fine. ATC queried about their altitude stating he couldn't see their altitude on his display, the crew advised they had switched the transponder source to the other pitot system, the altitude was subsequently correctly transmitted by the transponder. The aircraft entered a hold while the crew was attempting to troubleshoot the issue. The crew subsequently decided to return to Kansas City for a safe landing on runway 01L about 30 minutes after departure.
The aircraft remained on the ground in Kansas City for another 18 hours, then departed again, managed to position to Atlanta and entered service.
https://flightaware.com/live/flight/DAL9950/history/20210420/2010Z/KMCI/KATL
