Fractional flight crew reported making a wrong turn due to a communication breakdown with DCA Ground and confusion from inaccurate taxi diagrams that were missing taxiways.
Synopsis
Fractional flight crew reported making a wrong turn due to a communication breakdown with DCA Ground and confusion from inaccurate taxi diagrams that were missing taxiways.
Narrative
We waited approximately 30 minutes to push back from [Gate] XX at DCA. Ground Control was extremely busy; and transmissions were being stepped on regularly. We finally got clearance to push; then to taxi via J; and hold short of Runway 04. We were never given a flow time to ZZZ; or given any information about holding bays. When we were holding short of Runway 04; Ground gave us an instruction to turn right onto P and left on C to the holding bay. We responded but got stepped on. Then Ground gave us a new instruction; to turn right on Runway 04; then right on C; which we read back. As we proceeded; Ground told us that we had turned the wrong way on C; that we were supposed to have turned left on C; and instructed us to make a 180 on the ramp; then taxi south on C; cross Runway 04; and enter the holding bay for [Runway] 01. We read that back and complied.Because we had read back his instruction; we assumed that Ground had accidentally said right when he meant left. We knew for sure that we had written down and read back two right turns. However; after the event; the other pilot and I listened to the ATC recordings. Ground did in fact tell us to turn right on Runway 4; then left on C to enter the Holding Bay 01." It is also clear that our readback was "turn right on Runway 04 then right on C;" which Ground did not correct. Adding to our confusion was the fact that the taxi diagram does not identify C south of Runway 04; so it did not seem possible to make a left on C from our position.Lesson learned is that even if the frequency is congested; it is important to stop and take the time to ask for clarification if instructions seem confusing. We also could have improved our situational awareness if we had been more aggressive about asking Ground for a flow time; or about his intentions for us despite the congested frequency. Lastly; the taxi diagram should be updated to identify the name of the taxiway on the north side of Holding Bay 01. Is it [Taxiway] C or E? It is currently unlabeled; and I will be looking for the signage on my next DCA turn."
Second reporter narrative
Aircraft X called Ground upon pushback from [Gate] XX. Ground instructed to taxi J hold short Runway 04. While holding short Runway 04 Ground called and instructed right turn P; left turn C for run-up bay Runway 01 and then instructed to disregard. Ground called again and said right turn Runway 04; left turn C for the run-up bay Runway 01. Right turn onto Runway 04 and right turn onto C taxiway was readback. Airplane starting taxiing on C taxiway and Ground called. Said Aircraft X took a wrong turn and to do a 180-degree turn; cross Runway 04 and take C taxiway down to run-up bay for Runway 01. 180-degree turn was made and Aircraft X proceeded as requested. No further instances occurred.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.