Narrative:

I was training on local at the time and my trainee had a couple of things going on that we needed to catch up on. We needed to cross runway 16 with 2 aircraft; a BE20 was on a straight in; aircraft Y was just cleared to enter the right downwind runway 16 and land; aircraft X was cleared for takeoff; right turn out to the northwest approved; and aircraft Z was calling up to come in and land. My trainee went to clear the BE20 to land and I told him no way that aircraft Y was doing 250 knots and would beat him in all day. He cleared the BE20 [to land] number 2 and then went to cross only one of the aircraft. This got my attention focused on crossing the other aircraft. I was not expecting aircraft X to turn and climb so fast on there right turn out or that aircraft Y would descend down to pattern altitude because he usually remains high in the downwind banks the base in low and tight the pulls up to drop 60-80 knots on final. I also expected aircraft Y to be further in the downwind closer to base. Aircraft Y asked if we were talking to the cessna in the right downwind 200 feet above him. I looked back quickly to see him dipping to 013 and aircraft Y climbing to 017 northwest. I told him affirmative sir and he replied that was a bit close. He was then re-cleared to land. The BE20 was on a 4 mile final. I talked with my trainee and we discussed in scenarios like/ similar to this to have the departing aircraft fly south and we will call their turn to the northwest for traffic inbound from the southwest descending. Or we could hold both at separate altitudes till aircraft Y passed the cessna in the downwind.

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Original NASA ASRS Text

Title: FTW Controller reported an experimental aircraft had a near mid-air collision with a Cessna on downwind.

Narrative: I was training on local at the time and my trainee had a couple of things going on that we needed to catch up on. We needed to cross Runway 16 with 2 aircraft; a BE20 was on a straight in; Aircraft Y was just cleared to enter the right downwind Runway 16 and land; Aircraft X was cleared for takeoff; right turn out to the NW approved; and Aircraft Z was calling up to come in and land. My trainee went to clear the BE20 to land and I told him no way that Aircraft Y was doing 250 knots and would beat him in all day. He cleared the BE20 [to land] Number 2 and then went to cross only one of the aircraft. This got my attention focused on crossing the other aircraft. I was not expecting Aircraft X to turn and climb so fast on there right turn out or that Aircraft Y would descend down to pattern altitude because he usually remains high in the downwind banks the base in low and tight the pulls up to drop 60-80 knots on final. I also expected Aircraft Y to be further in the downwind closer to base. Aircraft Y asked if we were talking to the Cessna in the right downwind 200 feet above him. I looked back quickly to see him dipping to 013 and Aircraft Y climbing to 017 NW. I told him affirmative sir and he replied that was a bit close. He was then re-cleared to land. The BE20 was on a 4 mile final. I talked with my trainee and we discussed in scenarios like/ similar to this to have the departing aircraft fly south and we will call their turn to the NW for traffic inbound from the SW descending. Or we could hold both at separate altitudes till Aircraft Y passed the Cessna in the downwind.

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.