A320
Flight Crew Air Transport Pilot (ATP)
ATC Issue All Types; Conflict NMAC
Flight Crew Took Evasive Action
Human Factors
On climb out of Denver (Captain was PM; FO was PF); we were initially given a clearance to FL230. A minute or so later ATC reissued our clearance to maintain 16;000. We complied and the aircraft leveled at 16;000. ATC said something to the effect of once you are clear of traffic; we will climb you. We were trying to acquire the aircraft (which was said to be a glider); visually; but could not see it. I immediately looked at the TCAS and it displayed no targets. I changed mode from above to all; and it still showed no targets. ATC then said 'traffic no factor climb and maintain FL230'. As soon as she began to talk we got an RA immediately (the traffic was now showing on the navigation display) saying 'Descend; Descend; Descend'. The first officer immediately performed the memory items; disconnected the AP and began a descent. I responded to ATC by saying something like 'Unable; descending responding to an RA'. We descended about 300-400 feet and then we were clear on conflict. The glider flew about 400 feet on top of us slightly to our left; I am unsure of the lateral separation. After we ran the QRH and continued our climb to FL230; I checked with the flight attendants to make sure everything was ok in the cabin; everyone (including FAs) had still been seated in their jump seats with seatbelt fastened during the event. I began looking in the handbook for any further info. I found that this was indeed a NTSB reportable event and that an incident report was required. I followed the guidance and sent an ACARS to dispatch notifying them of the situation and providing the details outlined.As sent to dispatch:Prior to COORZ intersectionResponded to an RA while level at 16;000 ft descended about 300 feet; no dangerous articles onboard.I believe ATC should have vectored us off of course to avoid getting anywhere near the glider. As with gliders; they can rapidly change altitude and headings. While ATC did initially change our clearance from 23;000 to 16;000; perhaps a turn would have avoided this entire situation. I also think that because of rapidly changing altitudes abilities of a glider; that's why we were unable to initially acquire the target on TCAS.
A320 Captain reported a NMAC with a glider west of DEN at 16;000 feet.