Date: 201304
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Aircraft: PA-28 Cherokee/Archer/Dakota/Pillan/Warrior
Operator: Personal
Operating under: Part 91
Flight plan: VFR
Flight phase: Other VFR Traffic Pattern
Airspace: Class D ZZZ
ATC / advisory: Tower ZZZ
Second aircraft: Skyhawk 172/Cutlass 172
Reporter organization: Government
Reporter function: Local
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Communication Breakdown
Anomaly: ATC Issue All Types; Conflict NMAC
Detector: Person Air Traffic Control
Result: Air Traffic Control Issued New Clearance
Contributing factors: ATC Equipment / Nav Facility / Buildings
Primary problem: ATC Equipment / Nav Facility / Buildings

Narrative: I was instructing on LC1. Traffic was picking up and my trainee was working. Cherokee was entering the pattern from the Northeast; within 4-5 miles of the airport; VFR. We cleared a Cessna to depart VFR on a right downwind departure. I was aware that the two could be a potential conflict as it is a hot spot for our Tower due to the neighboring Class C airspace. I made the decision to over key and change the Cessna to a left downwind to alleviate the conflict with plenty of time to discuss it with my trainee. Cessna did not respond. I issued the clearance two more times with no response. I then began to give him the traffic again with no response from Cessna. I then began to believe that it was an equipment failure on my part as the instructor jack on LC1 has been a noted problem (previously an aircraft did not receive a go-around clearance as the transmissions were not going out; and another instructor was also unable to key over his trainee); but we've been told it's alright to use. I did not trust that my transmissions were going out and unplugged my trainee and took his/her jack and continued and even tried another controllers push to talk when my transmissions did not receive an answer. Due to the positioning of the Cessna to the Cherokee; behind and below in a potential blind spot; I did not issue instructions to the Cherokee as I wanted him to continue his present course to avoid traffic; turning left could put him into the downwind departure exacerbating the conflict; a right towards the runways could put him into arrivals/go-arounds. The Cherokee then began saying 'I wish you could have pointed that traffic out to us' I told him I had been trying to change the Cessna but my transmissions were not going out. He replied that he had heard all my transmissions; which is possible but if at one point I wasn't transmitting he wouldn't know. After the Cherokee finished one transmission; he started into another question asking if the Cessna was remaining in the pattern. I replied that the Cessna was a downwind departure. While the Cherokee was talking the Cessna had moved to the left of the Cherokee and below him slightly behind. The Cessna then pulled up outside the Cherokee and now slightly ahead. The Cherokee started a left turn towards traffic and terrain; and said 'I'm making a left here.' I told him to continue in the left 360 sequenced the Cherokee in the pattern. The Cessna left our airspace to the South without incident as traffic had to be prioritized following the Cherokee's time consuming on frequency statements. The controllers do not have full faith in some of our equipment. We've reported the issue; and units have been swapped around the Tower or given a once over. Maintenance has stated they'd like to replace; or do detailed inspections; but are not getting allotted the time or money by their higher ups so we are putting band aids on the problems and playing shell games. At one time the instructor jack on LC2 was reported to have problems with recording or transmissions; the post it note that was affixed to it to tell us this important fact is missing; the unit could have been moved to LC1; but we don't know. It is amazing that we can spend tens thousands of dollars sending two certified letters to tens of thousands of employees to tell them what they already know but getting safety related equipment fixed/replaced falls by the way side.




Synopsis: Tower Controller providing OJT issued a turn change to a departure that went unheeded apparently due to a long standing problem with radio jacks in the cab; the turn failure resulted a significant conflict event.