Center controller and GA pilot reported the pilot had radio issues and squawked the incorrect transp...

Attributes
ACN	1584545
Time
Date	201810
Local Time Of Day	1801-2400
Place
Locale Reference	ZOB.ARTCC
State Reference	OH
Environment
Flight Conditions	Marginal
Aircraft 1
Make Model Name	Small Aircraft Low Wing 1 Eng Fixed Gear
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Route In Use	Direct
Flight Plan	IFR
Component
Aircraft Component	Air/Ground Communication
Person 1
Function	Enroute
Qualification	Air Traffic Control Fully Certified
Person 2
Function	Single Pilot
Qualification	Flight Crew Multiengine Flight Crew Air Transport Pilot (ATP) Flight Crew Flight Instructor Flight Crew Instrument
Experience	Flight Crew Last 90 Days 230 Flight Crew Total 4000 Flight Crew Type 600
Events
Anomaly	ATC Issue All Types Aircraft Equipment Problem Less Severe Deviation - Procedural FAR Deviation - Procedural Published Material / Policy

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.

Original NASA ASRS Text

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

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.

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.

Center controller and GA pilot reported the pilot had radio issues and squawked the incorrect transponder code.