Date: 201508
Local time of day: 1801-2400
Location: ZZZ.Tower, US
Flight conditions: VMC
Weather elements / visibility: Haze / Smoke
Light: Daylight
Aircraft: SR22
Operator: FBO
Operating under: Part 91
Flight plan: VFR
Mission: Training
Flight phase: Final Approach
Airspace: Class D ZZZ
ATC / advisory: Tower ZZZ
Second aircraft: PA-46 Malibu/Malibu Mirage/Malibu Matrix
Reporter organization: Government
Reporter function: Local; Instructor
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Communication Breakdown; Confusion; Troubleshooting; Situational Awareness; Training / Qualification; Time Pressure
Second reporter function: Instructor
Anomaly: ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Clearance
Detector: Automation Air Traffic Control; Person Flight Crew; Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented; Flight Crew Took Evasive Action
Contributing factors: Environment - Non Weather Related; Procedure; Weather
Primary problem: Procedure

Narrative: I was training a 100 hour Developmental on the Local position which was combined with ground at the time. After sitting for 45 minutes with no traffic; traffic built quickly and we immediately had 3 arrivals from radar. The Cirrus was on a downwind and the Malibu was on a 4 mile final. The Cirrus was cleared touch and go and number one and the Malibu was cleared to land number two behind the Cirrus. When the Cirrus took his base out a little further than expected; I told the developmental to tell the Cirrus to cross final and rejoin the opposite down wind. The Cirrus was not in a good spot to be in front of the Malibu and I was taken by surprise by this. I am not sure if the Cirrus actually extended his downwind slightly; or made a dogleg base; and ended up much closer to the Malibu than I thought they would be. It is possible that when I told the Cirrus to cross final he maneuvered off the normal base because he did not understand what I needed him to do. Just prior to the conflict alert (CA/CA) going off; I got them both in sight in the haze and realized they were not where I thought they were initially.As the CA/CA went off; I told the Cirrus to fly eastbound immediately; and the pilot complied as he was already turning to avoid the Malibu on 2 mile final.Well; honestly; the only recommendation I can make is that I should not let a developmental go as far as I did. This is a pretty common recommendation; from the [Safety] Briefings I have read; and it looks like I got caught in the classic trap.


Second narrative: I was on a VFR cross country with my student from ZZZ. We filed a VFR flight plan and picked up VFR flight-following to our destination. We were instructed to enter a left downwind for Runway 24 by Approach and then contacted Tower. Tower then cleared us to land; and I responded telling tower we wanted a touch-and-go; since we were heading right back to ZZZ. We were then cleared for the option. Once we were on downwind and abeam the approach end of the runway; my student let tower know our position (flight school procedure at our home airport); and then we were cleared for the option. I then hear tower notifying another aircraft of our position; saying we were on left base when we were still on downwind. I did not tell tower that we were still on downwind; since we were nearing our base turn. Once we were on base; I heard another aircraft cleared to land the same runway. Immediately after; tower instructed us to cross final path and enter a right base for the same runway. I read back the clearance; and looked to my right (farther up final approach path) and saw an aircraft in close proximity on final for 24. This aircraft was on collision course with ours. I immediately took evasive action; banking hard right with full power. As I did this; I saw the other aircraft bank away as well. I then was downwind again; and told tower as we joined final approach course again.I am not sure if haze was a factor; but I did not see the other aircraft until stated above. The visibility was reported at 10SM; however at altitude I would say it was closer to 4 or 5SM. Also; I do not remember our traffic alert system notifying us of any nearby traffic. I believe I followed every ATC instruction. I was not fatigued or physically affected in any way; and my student stated the same. Looking back on it; I should have questioned ATC about the instructions to cross through final approach path and enter a right base; rather than just reading back the instructions.


Synopsis: A Controller supervising a Developmental and an Instructor Pilot report the Student Pilot delayed the base turn which caused a conflict with another aircraft on final. The Developmental Controller was slow to resolve the conflict so the Supervisory Controller interceded.