Date: 201901
Local time of day: 0001-0600
Location: DCA.Airport, DC
Flight conditions: IMC
Weather elements / visibility: overcast
Aircraft: A320
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Climb
Airspace: Class B DCA
ATC / advisory: TRACON PCT
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Human factors: Communication Breakdown; Time Pressure
Anomaly: Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Became Reoriented; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Returned To Clearance
Contributing factors: Airspace Structure; Procedure; Weather
Primary problem: Weather

Narrative: We were cleared to depart DCA on the HORTO3 departure off RWY 1. This is never a comfortable operation due to the close proximity of two high profile restricted areas in the Washington DC metro area and the convoluted departure procedures used to mitigate the risk of penetrating said restricted areas. Normally I want to be the Pilot flying in these cases; but in this instance; I had flown the leg in the afternoon prior due to forecasted weather and my unfamiliarity with my First Officer. [However]; I had grown to trust this pilot and was impressed with his intellect; skill and attention to detail.During preflight briefing; we had discussed the departure procedure and our required actions three times to establish the importance of flying the HORTO3 as charted to clearly avoid the restricted areas and to fly up the Potomac River. I felt comfortable with the situation as we pushed off the gate. It turned out to be a relatively quick taxi and it's fair to say we were a bit rushed taking the runway and cleared for takeoff. However; required checklists were completed and the aircraft was ready for flight in all respects.As briefed; we climbed away from the runway; pulled heading and turned left to 330 degrees; Autopilot 2 on and direct to ADAXE via NAV mode. The track and progress appeared normal to me.I had looked away from the displays to locate the checklist and took a quick peak at my FMS; when I looked up again; I saw a white box on my PFD indicating that we were now in HDG mode. I did not know why were no longer in NAV and exactly when he had pulled the HDG knob; or if we had experienced a navigation failure of some kind. I was puzzled and unnerved based on our proximity to Washington DC and the crosswind that was certainly pushing us towards trouble. To say I was surprised is an understatement.I raised the alarm with words along the lines of 'why are we in heading mode; we need to stay on the departure...' I gathered the Pilot Flying had felt we weren't tracking correctly towards ADAXE and was going to 'fix it' by putting the aircraft's lateral guidance into his hands using HDG mode. I can't recall with certainty; but I believe the HDG selected was around 005. It is difficult to discern the aircraft's track in this mode; but based on the relative motion of fixes displayed on the NAV screen; we appeared to be on a track that would take us north east of ADAXE towards metro Washington DC and near restricted areas P-56A and P-56B; which aren't displayed on our NAV screens but I knew they were close.During everything I am describing; I was running the After Takeoff Checklist and getting a frequency change to Potomac Departure. I checked on quickly and got a friendly reply from the Controller. He then asked 'Are you guys on a departure?' to which I replied; 'We've dropped the departure.'I said this because I wasn't sure exactly what the nature of our navigation problem [was]. Was it a FMS problem? Was it a sensor failure or had we (the crew) made a mistake? I needed to quickly convey that we needed help to get back on course and that statement; at that moment; seemed to be the most expedient way to do so.To my eternal gratitude; the Controller quickly gave us a left turn heading 330. We selected 330 and I also told the Controller the wind at our altitude was 221 at 41 kts. He then followed up by issuing a clearance to turn to heading to 310; then direct HORTO intersection soon after. Everything I've just described happened very rapidly because of the close proximity to the restricted areas; and there was very little time for analysis and crew communication to collaborate on a solution. In short; the situation snowballed fast and we were bailed out of it by an attentive controller.Every bit of radar tracking and GPS data available to us seems to indicate we avoided both aforementioned restricted areas.Suggestions: 1. This particular departure from the airport is high risk in many respects. The most experienced crew member should always fly it. Despite the fact that it was the FO's turn to fly; I should have flown the departure. I've done it many times; he had only done it 3-4 times.2. Remove the restricted areas from the metro DC area. This may seem like heresy; but these restricted areas are so close to a very busy airport used by jet aircraft at speeds that didn't exist when the city; landmarks and the airport itself were established. We have to operate outside of normal procedures to make it work even on a good day. Either change the airport's operations or remove the restrictions to the airspace.3. Display the permanent airspace restrictions on our Nav displays. If you're not going to remove these restrictions to airspace; at least program the FMS/FMGC to show it on our displays. If I can see it on my screens; it is much more likely I'd be able to avoid it.




Synopsis: A320 Captain reported an RNAV departure course deviation resulted in the aircraft tracking in close proximity of two high profile restricted areas.