Date: 201705
Local time of day: 1801-2400
Location: DCA.Airport, DC
Flight conditions: VMC
Light: Night
Aircraft: Medium Large Transport; Low Wing; 2 Turbojet Eng
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach
Airspace: Class B DCA
ATC / advisory: TRACON PCT; Tower DCA
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Second reporter function: First Officer; Pilot Not Flying
Anomaly: Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT; Inflight Event / Encounter Unstabilized Approach
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Flight Crew Returned To Clearance; Flight Crew Became Reoriented
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: During the DCA River Visual Runway 19 approach (night VMC); a few actions happened in quick succession. The first happened when we were reconfiguring the airplane for the approach. I called for flaps 3; after a few seconds; I looked over and saw the flap selector in the flaps 4 configuration. I mentioned this to the FO who reconfigured the flap selector back to flaps 3. At the time; I was hand flying the airplane. Whilst my attention was on the flap configuration; I unintentionally must have lowered the nose of the airplane causing the GPWS to call out 'Pull Up; Pull Up; Obstacle' to annunciate. I quickly added power and raised the nose of the airplane to arrest the GPWS.Don't fixate on any one thing. Keep a good awareness of what is happening around you.


Second narrative: I was pilot monitoring for this leg and we were performing the River Visual 19 into DCA in night VMC conditions. Prior to being cleared for the approach; we were being vectored by ATC. We were instructed to slow to 170 kts and descend to and maintain 3000 ft. We were further instructed to slow to 150 kts; maintain 3000 ft and advise when we had the river in sight. I repeated the instruction with no correction from ATC. We slowed to 150 kts; and at this point we were at 3000 ft just northwest of FERGI. ATC asked if we had started our turn south yet and I advised we had the river in sight. He then asked if we turned south yet and 'I said no; what was the heading.' He said 150 degrees and advise when we have the river. We complied; turned to 150 degrees; advised we had the river insight and ATC subsequently cleared us for the approach. The controller then said to maintain 170 kts until 5 DME. During this; the captain had called for flaps 3 and I missed the detent and went to flaps 4 by mistake. In the confusion; I didn't notice but the captain caught it. I went back to flaps 3 and we continued on with the approach. ATC told us to switch to tower. Tower told us we were cleared to land. We continued descending on the approach and finished configuring. Our descent rate was roughly 600-700 fpm. Further in on the approach; tower advised us there was a helicopter behind and below us and after his transmission; we received a traffic alert. I was looking for the traffic outside and on the MFD and trying to maintain the airfield. Between 700-800 ft we received a GPWS caution followed by a warning. We were about 3 DME from DCA; near the cluster of hotels when we received the warning. The captain pulled up and leveled-off at an altitude more consistent with our point on the approach; the warning ceased; and we continued on with the approach. At 500 ft; we were on a proper descent path; at our approach speed and in a safe position to land. We landed and taxied to the gate. In hindsight; as pilot monitoring; there were many factors that lead to the GPWS warning and it started before the approach. The confusion between us and the controller helped facilitate me selecting the wrong flap setting and not realizing it due to my attention being split. The traffic alert on the approach broke my attention away from monitoring the approach momentarily. These all helped me to not realize that we had gotten low on that segment of the visual approach ultimately leading to the GPWS warning for obstacles on the visual. After the captain reacted; the warning went away and we were back on the correct descent angle for the approach. The correct action would have been; as pilot monitoring; to immediately call for the go-around when we received the warning.


Synopsis: Air carrier flight crew reported on a night River Visual Runway 19 to DCA they received a GPWS obstacle warning and continued to a landing.