Narrative:

As we were on short final to runway 22L at ZZZ; about 300' from touchdown; we were told to go around by ZZZ tower. There was another company aircraft that had been cleared for takeoff; but had taken the runway very slowly; for some reason they did not start their takeoff roll immediately. We did our normal go-around procedure and flew runway heading as instructed. At about 1000' AGL we got a TCAS (traffic collision avoidance system) alert 'traffic; traffic.' we looked out our front window; and to our astonishment we saw a [another] aircraft slightly above 100'-200' and less than 1/4 mile. It could have been as little as a few hundred feet in front. It was so close I could see his flap retractions. We leveled off at 1000' to allow him to climb out and get some altitude separation. We did not get an RA (resolution advisory) probably because it is inhibited below 1000' RA. The tower did not say anything to either aircraft and I'm not sure they were aware of our close proximity. They told us to contact departure control and we were given an immediate turn to the south for another rnp (required navigation performance) approach and landing. My first officer (first officer) and I discussed this at length at the gate and we were in agreement that we were given a fly runway heading clearance. Apparently the aircraft that we went around for had finally started his takeoff roll as we were doing our go-around. If he would have started his takeoff roll about one or two seconds later; it could have ended in disaster as he couldn't see me and I couldn't see him; and with both aircraft TCAS RA inhibited.for runway heading clearances on go-around for aircraft on the runway takeoff clearances should be canceled.

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Original NASA ASRS Text

Title: ZZZ Tower Controller and air carrier Flight Crew reported a near mid-air collision during go-around with a departing aircraft on the same runway.

Narrative: As we were on short final to Runway 22L at ZZZ; about 300' from touchdown; we were told to go around by ZZZ Tower. There was another Company aircraft that had been cleared for takeoff; but had taken the runway very slowly; for some reason they did not start their takeoff roll immediately. We did our normal go-around procedure and flew runway heading as instructed. At about 1000' AGL we got a TCAS (Traffic Collision Avoidance System) alert 'Traffic; Traffic.' We looked out our front window; and to our astonishment we saw a [another] aircraft slightly above 100'-200' and less than 1/4 mile. It could have been as little as a few hundred feet in front. It was so close I could see his flap retractions. We leveled off at 1000' to allow him to climb out and get some altitude separation. We did not get an RA (Resolution Advisory) probably because it is inhibited below 1000' RA. The Tower did not say anything to either aircraft and I'm not sure they were aware of our close proximity. They told us to contact Departure Control and we were given an immediate turn to the south for another RNP (Required Navigation Performance) approach and landing. My F/O (First Officer) and I discussed this at length at the gate and we were in agreement that we were given a fly runway heading clearance. Apparently the aircraft that we went around for had finally started his takeoff roll as we were doing our go-around. If he would have started his takeoff roll about one or two seconds later; it could have ended in disaster as he couldn't see me and I couldn't see him; and with both aircraft TCAS RA inhibited.For runway heading clearances on go-around for aircraft on the runway takeoff clearances should be canceled.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.