Narrative:

I was providing on the job training on our combined local south position. We were active runway 8R and runway 8L; advertising visual approaches (all of our instrument approaches go to RY26R; therefore we run a lot of opposite direction practice/actual approaches.) we are not active 8s often; so when we are our pilots are less familiar and it's more difficult for us controllers as well. My trainee had departed aircraft X; requesting straight out and had moved on to working other aircraft.I saw aircraft Y inbound; opposite direction from the east with 'vl' in his data block; indicating a visual approach to the left runway; I assumed it was for runway 8L. I told my developmental to do something with the aircraft X; he did not hear me. I told him again and the closure rate was so fast by the time he could issue instructions; I had to step in and issue a traffic alert and turned the aircraft X to the south; expecting aircraft Y to turn northwest. A visual approach to runway 8L would normally be issued to circle north of the field for a left downwind entry. Socal approach had apparently also issued the south turn to aircraft Y but it was hard to tell as fusion showed the targets all over the place. The aircraft missed by about a mile and maybe 100 feet. When we established communication with aircraft Y he told us that sct had set him up for a visual approach to runway 26L; which we knew nothing about; there had been no coordination. We were unable to communicate with the aircraft X after traffic had passed and he appeared to climb into the ont class C eastbound. I don't know what could happen to better facilitate the approach issue with sct; but as far as the aircraft proximity; I should step in earlier next time. I like to give my developmental the opportunity to fix problems; even if I have to prompt them. However with that closure rate I should have just keyed up and fixed it myself early enough that it was not a safety issue.

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Original NASA ASRS Text

Title: CNO Tower Local Instructor reported seeing a conflict and hoping the developmental would fix the problem. Instructor prompted developmental to no avail. Arrival and departure had a loss of separation due to timing and lack of communication from overlying TRACON.

Narrative: I was providing On the Job Training on our combined Local South position. We were active Runway 8R and Runway 8L; advertising visual approaches (all of our instrument approaches go to RY26R; therefore we run a lot of opposite direction practice/actual approaches.) We are not active 8s often; so when we are our pilots are less familiar and it's more difficult for us controllers as well. My trainee had departed Aircraft X; requesting straight out and had moved on to working other aircraft.I saw Aircraft Y inbound; opposite direction from the east with 'VL' in his data block; indicating a visual approach to the left runway; I assumed it was for Runway 8L. I told my developmental to do something with the Aircraft X; he did not hear me. I told him again and the closure rate was so fast by the time he could issue instructions; I had to step in and issue a traffic alert and turned the Aircraft X to the south; expecting Aircraft Y to turn northwest. A visual approach to Runway 8L would normally be issued to circle north of the field for a left downwind entry. SoCal approach had apparently also issued the south turn to Aircraft Y but it was hard to tell as FUSION showed the targets all over the place. The aircraft missed by about a mile and maybe 100 feet. When we established communication with Aircraft Y he told us that SCT had set him up for a visual approach to Runway 26L; which we knew nothing about; there had been no coordination. We were unable to communicate with the Aircraft X after traffic had passed and he appeared to climb into the ONT Class C eastbound. I don't know what could happen to better facilitate the approach issue with SCT; but as far as the aircraft proximity; I should step in earlier next time. I like to give my developmental the opportunity to fix problems; even if I have to prompt them. However with that closure rate I should have just keyed up and fixed it myself early enough that it was not a safety issue.

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.