Date: 201810
Local time of day: 1801-2400
Location: ZOB.ARTCC, OH
Flight conditions: Marginal
Aircraft: Small Aircraft; Low Wing; 1 Eng; Fixed Gear
Operator: Personal
Operating under: Part 91
Flight plan: IFR
Mission: Personal
Flight phase: Cruise
Airspace: Class E ZOB
ATC / advisory: Center ZOB
Aircraft component: Air/Ground Communication
Component problem: Malfunctioning
Reporter organization: Government
Reporter function: Enroute
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Communication Breakdown
Second reporter function: Single Pilot
Anomaly: ATC Issue All Types; Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Air Traffic Control Issued New Clearance; Air Traffic Control Issued Advisory / Alert; Flight Crew Overcame Equipment Problem; Flight Crew Became Reoriented; Flight Crew Requested ATC Assistance / Clarification
Contributing factors: Aircraft; Human Factors
Primary problem: Human Factors

Narrative: Aircraft X started squawking 7500. The Radar Controller (R-Side) was unable to reach Aircraft X on the radio to confirm if they were intentionally squawking 7500. When Aircraft X first started squawking 7500 I was moved to assist the radar Controller as the Assist Controller. Due to the nature of the event and traffic in the sector I did not have time for a full recorded briefing before I had to start coordination with the adjacent Center. While I was coordinating with TRACON; the R-side managed to briefly regain communications with the pilot and was able to confirm that the pilot had a radio failure and had mistakenly input 7500 instead of 7600 (Radio Failure). The pilot then descended to 10;000 feet. I was not there when the pilot was initially issued 9000 feet so I have no idea of whether or not he received his descent clearance at the TRACON/Center boundary. As part of my coordination I had already coordinated that this aircraft was out there and we had no idea of what his intentions were. Aircraft X was then handed off to TRACON and I was relieved from position.Emphasize training to pilots about the difference between [squawk codes] and what could happen if you accidentally enter the wrong one. Especially at locations near sensitive areas.


Second narrative: I was in cruise at 11;000 feet. I had one passenger (non-pilot) in the front seat with me. I was speaking to Cleveland Center at the time of the event. I had picked up the weather; it showed visual conditions with rain in the area. I felt confident that apart from the bumpy ride the arrival would be uneventful. There was a buzz in my head set and I was unable to speak to my passenger through the headset. I was able to hear all radio communications with Center at the time. I was not able to respond to their calls though. I squawked 7600 however due to the bouncing around from the turbulence I was experiencing I inadvertently pressed the number 5 instead of 6. In the heat of the moment I went straight back to flying the airplane and troubleshooting the radio issue without realizing what I had done. The whole time I was able to hear Center and other flights in the area. They all called me and I could hear them however they were not able to hear me respond verbally. I did try to respond when they were trying to establish communication by pressing ident after the controller's requests. The two airplanes that tried communicating with me acknowledged they could hear I was trying to respond but could not actually hear any words. After troubleshooting I was able to regain the use of my radios. I checked in immediately with Center. The controller immediately asked what I was squawking. That is when I realized that I had the wrong code. I changed it to 7600 immediately and admitted what I had done. They handed me off to TRACON. I apologized for the confusion this had caused and moved on to the next frequency. TRACON had me do some 'verification' turns and told me to return to my previously squawked code. They cleared me to and I flew an approach and landed. The tower controller gave me the numbers to Center and TRACON and I spoke with them about what happened. Both of the gentlemen I spoke to were very professional and both commented that I did exactly what I was supposed to - fly the airplane first. It was unfortunate that I was on the wrong code. The event was a perfect storm. It was bumpy; the radios failed and I was in very busy airspace. I had a nervous passenger on top of that as well. I maintained control of the aircraft the entire time. I worked the radio problem on top of dealing with a constant barrage of communication and tried to respond to all the calls throughout the troubleshooting of the radio. I made every effort to remain calm and work the issue. Only after fixing the radio issue and reestablishing communications with Center did I realize the error I had made on the squawk code. I think my biggest failure was failing to verify what I had input in the transponder. This is a mistake that will haunt me for the rest of my career. Personally; I think that beating myself up over this ordeal has ensured self-correction especially with transponder codes but numbers as a whole. Always verify!


Synopsis: Center Controller and GA pilot reported the pilot had radio issues and squawked the incorrect transponder code.