Date: 201412
Local time of day: 0601-1200
Location: ZDC.ARTCC, VA
Flight conditions: VMC
Weather elements / visibility: Turbulence
Aircraft: EMB ERJ 170/175 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Climb
Airspace: Class E ZDC
ATC / advisory: Center ZDC
Aircraft component: Autoflight System
Component problem: Improperly Operated
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Second reporter function: Pilot Not Flying; First Officer
Anomaly: ATC Issue All Types; Aircraft Equipment Problem Less Severe; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew Overcame Equipment Problem; Flight Crew Returned To Clearance
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: I was the PM. We departed Runway 1 out of DCA. Followed the 328 DCA radial. After about 10 minutes ATC gave us a 070 heading. After another 5 minutes they gave us direct SWANN. At some point we both remember getting a 90 heading from ATC. As we passed BROSS ATC told us to turn to a heading of 010 then asked if they left us on a heading. We said a couple of frequencies ago they gave us a 90 heading. Leading up to this event we received numerous heading; alt; and speed changes. Again we are not 100% sure of them giving us a 90 heading. Between getting the speed; alt; and heading changes; the only other thing I can think of is that when we received direct SWANN the PF never pressed the NAV button. A lot of times when given several instructions some pilots will spin the heading bug in the direction of the fix to get the turn started then maybe throw in the new altitude or speed. Bottom line we either missed pressing NAV or was given the 90 heading and ATC forgot that we were on it.


Second narrative: Departed KDCA via NATL3 departure; runway 1. Was issued a 010 heading and proceeded as instructed for about 25 nm. Next; was issued a right turn to heading 070 and proceeded for roughly 5nm. Afterwards; was issued 'Proceed direct SWANN'. I first turned the heading bug to a 090 heading to get us going towards SWANN. I properly selected the FMS to proceed direct SWANN; and confirmed with the Captain. I cannot recall at this point whether or not I pressed the 'NAV' button. At this point the aircraft was proceeding towards SWANN and along our flight plan route. Between SWANN and BROSS intersections; we were issued various commands to avoid traffic. I cannot recall exactly all the altitude; speed; and/or course changes that were issued. This is due to the fact that I was reviewing aircraft manuals on the iPad. Our position Was now due east of BROSS and off-course to OOD when Washington Center issued a 010 heading. At this point I spun the HDG knob to 010 and pressed the HDG button. It was then; the aircraft entered ROLL mode. I pressed the HDG button a second time and the aircraft entered HDG mode. At this point; both the captain and I were confused as to why the aircraft would first enter ROLL mode since we both thought we were engaged in LNAV mode. After a brief period of time; we we're cleared to 'Redirect OOD and proceed on course'. The entire flight thereafter proceeded without incident.Due to the fact that pressing HDG upon selecting 010 on the knob caused the aircraft to enter ROLL mode; it is logical to assume that the aircraft was in HDG to begin with. It is unsure if we were correctly in HDG mode from avoiding traffic; if we were supposed to be in NAV mode from the point of receiving direct SWANN.There are a few ways this episode could have been prevented. Firstly; upon confirming FMS inputs with the other flight crew member; not only should the flying pilot select the proper autopilot modes on the panel; but the pilot should verify on the PFD that the proper modes are being carried out. Secondly; due to the nature of the flight; the pilot flying should not be heads-down on the company iPad; despite reviewing company manuals for operation. This task isn't time-sensitive and thus could have been carried out in a low-stress environment such as while not performing flight duties or perhaps in cruise flight while proceeding on-course. Finally; having had a heightened situational awareness as to exactly where and how the aircraft was navigating could have eliminated all confusion on the matter.


Synopsis: A track deviation resulted when the flight crew of an ERJ-175 failed to monitor and insure intended auto-flight modes when departing DCA on the NATIONAL DEPARTURE.