Date: 201902
Local time of day: 0001-0600
Location: DCA.Airport, DC
Aircraft: EMB ERJ 170/175 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Takeoff / Launch
Airspace: Class B DCA
ATC / advisory: Tower DCA
Aircraft component: GPWS
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Human factors: Situational Awareness
Second reporter function: First Officer; Pilot Flying
Anomaly: Aircraft Equipment Problem Less Severe; Inflight Event / Encounter CFTT / CFIT
Detector: Automation Aircraft Terrain Warning
When detected: In-flight
Result: Flight Crew FLC complied w / Automation / Advisory; Flight Crew Took Evasive Action
Contributing factors: Aircraft; Human Factors
Primary problem: Ambiguous

Narrative: We took off from Runway 1 in DCA. We were on the REBLL4 departure. Wet runway; no flex. MTOW was 77.6 and our T/O weight was around 76.6. Winds 190/7. Temperature 8C and pressure of 29.96. Visibility was 5 NM BR and BKN 006. I was PM (Pilot Monitoring) and had WX radar on and PF (Pilot Flying) had Terrain on. We were at about 350 when we first received a 'Caution Terrain' caution message. As that happened PF was requesting NAV mode. Then we received a 'Pull Up; Terrain' indication. We followed Terrain avoidance procedure and applied Max Thrust. We had very little margin between Pli and low speed awareness. Meanwhile Tower switched us over to departure. We stayed on the SID as we tried to avoid P56. We continued the climb and we were out of the condition within seconds. Everything happened in a few seconds.Terrain mode was always showing green and positive clearance from obstacles. We switched controllers again and didn't have a chance to notify ATC about the event. We continued the climb and the rest of the flight without any major issues. We were on the vertical and lateral path for the SID. At least that's what we could see in our display. We can't really tell if it was a system malfunction or if it was a legitimate event because we were IMC. So we applied the recovery procedures. If it was a system malfunction I would say it could have been a momentary dual radio altimeter failure that triggered an unwanted alert. But if it was a real event I would imagine that the wind pushed us further to the North of the path than what we thought we were in which case it might be appropriate to maybe slightly modify the departure or simply do not take off with no tail wind at all. But what the other instruments were showing us differ from the EGPWS alert.


Second narrative: Runway 1 REBLL4 departure out of DCA. Wind 190@7 wet runway. Flaps 2 take off No Flex. I was PF (Pilot Flying.) After rotation right before 400 we got 'caution terrain' then at 400 as I called for FMS NAV; we got 'terrain; terrain; pull up' so we initiated the escape maneuver applied Max thrust and pitched up while respecting the PLI While also staying on the Rebbll4 departure to avoid P56. No deviations or whatsoever occurred as we continued with the SID. It was just like a normal departure but with Max Thrust. We reduced power back to normal climb settings shortly after the message when we were sure we were clear of terrain and proceeded with the SID without advising ATC that we got a EGPWS message. We were not sure how or what caused the alert. I had terrain on my PFD and weather on the Captain's side. We find it unusual that we got the alert on a normal take off; normal rotation. Tailwind could be a factor. Maybe a false alert?


Synopsis: EMB-175 flight crew reported receiving an EGPWS terrain alert departing DCA that may have been a false alert.