Narrative:

Taxiing out we were to hold short of [taxiway] and contact ground. The first officer (first officer) transmitted but ATC did not hear him; we tried again and then I tried on my side to contact ground; they did not hear us. Ground control then called 'who's at [taxiway]?' and we could not reply. I asked the first officer to switch to comm 2 and try again; that was successful. We were given the runway assignment and taxi clearance. I started following the given route to the runway. While taxiing I tried to see if any button or knob was out of place so we could transmit; but to no success. As we got closer to the runway I determined that rtu 1 (radio tuning unit) was not transmitting; but was receiving. I discussed the possibility of contacting maintenance. I was trying to figure out what to do; and did not have a solid answer whether to go or not. After discussion with the first officer about far's dealing with IFR flight on one radio; I came to the decision to go on the flight because we had comm 3 available as a backup and I still could receive on comm 1. That was a mistake. Enroute I ACARS maintenance control and they advised to call when on the ground. I also notified dispatch of the problem. As we flew I checked the QRH vol 1 to find any answers and read a min. Equipment list that stated only 1 VHF is needed for flight; so I felt justified in departing; figuring we would be able to defer the radio. I talked with maintenance control and we came to the conclusion that the comm 1 was broken. I asked maintenance to defer the radio and was told that comm 1 is not deferrable because it's on the hot bus bar for emergency power loss. That's when I realized I made a mistake in departing.

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Original NASA ASRS Text

Title: CRJ-200 flight crew reported departing with Comm 1 transmitter inoperative; but discovered after landing that Comm 1 was not deferrable.

Narrative: Taxiing out we were to hold short of [taxiway] and contact ground. The FO (First Officer) transmitted but ATC did not hear him; we tried again and then I tried on my side to contact ground; they did not hear us. Ground control then called 'who's at [taxiway]?' and we could not reply. I asked the FO to switch to comm 2 and try again; that was successful. We were given the runway assignment and taxi clearance. I started following the given route to the runway. While taxiing I tried to see if any button or knob was out of place so we could transmit; but to no success. As we got closer to the runway I determined that RTU 1 (Radio Tuning Unit) was not transmitting; but was receiving. I discussed the possibility of contacting Maintenance. I was trying to figure out what to do; and did not have a solid answer whether to go or not. After discussion with the FO about FAR's dealing with IFR flight on one radio; I came to the decision to go on the flight because we had Comm 3 available as a backup and I still could receive on Comm 1. That was a mistake. Enroute I ACARS Maintenance control and they advised to call when on the ground. I also notified Dispatch of the problem. As we flew I checked the QRH vol 1 to find any answers and read a Min. Equipment List that stated only 1 VHF is needed for flight; so I felt justified in departing; figuring we would be able to defer the radio. I talked with Maintenance control and we came to the conclusion that the Comm 1 was broken. I asked Maintenance to defer the radio and was told that Comm 1 is NOT deferrable because it's on the hot bus bar for emergency power loss. That's when I realized I made a mistake in departing.

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.