Date: 202101
Local time of day: 1801-2400
Location: ZZZ.ARTCC, US
Flight conditions: IMC
Weather elements / visibility: Icing
Light: Night
Aircraft: EMB ERJ 170/175 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Climb; Initial Climb
Aircraft component: Radio Altimeter
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
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Clearance
Detector: Automation Aircraft RA; Person Flight Crew
When detected: In-flight
Result: Aircraft Equipment Problem Dissipated; Flight Crew Returned To Clearance; Flight Crew Took Evasive Action; Flight Crew Overcame Equipment Problem; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: We were on the ground at ZZZ for a prolonged time (Approx 1.5 hours) due to a previous flap issue on arrival. After contract Maintenance fixed the issue; we taxied to de/anti ice. That took about another 30 minutes before taking off. Prior to departure all takeoff protocol was followed with all checklists completed. The FMS was set up per the ZZZ2 Rwy XX Departure company page of TO-1/CMB-1 with flaps 2. We also used anti ice-all; with compact snow for the runway conditions. The terrain maps were configured to both our MFP's as well. ATIS was reporting light snow/ 1 to 5 miles visibility with about a 7 kt headwind for runway 19 at the departure time. Temp was around -4 C. It was also night. The First Officer (FO) was the Pilot Flying. I believe we had around 24 passengers with 9200 pounds of fuel at takeoff. Once cleared to takeoff; we taxied into position on the runway 19 threshold and the FO conducted a full static takeoff. We rotated towards the last one third of the runway and promptly retracted the gear. The FO pitched into the flight director with over a thousand foot climb rate. Everything appeared normal. At about approx 30 seconds to a minute into the climb; the terrain aural went off. We then conducted the CFIT profile and monitored our climb and speed. I paid particular attention to my RA which was showing -5 feet. I then looked at our course and we were perfectly centered on the course line and the terrain maps were showing nothing but green ahead. After the terrain warning seemed to be over; I pulled the thrust levers back to the TOGA detent. Once back in the TOGA detent; the terrain aural sounded again. Again; we conducted the CFIT profile. I scanned my RA a second time and it still bounced around -5 feet. The terrain overlays on both MFD's still showed only green ahead and around us. Once the terrain aural silenced the second time; the FO brought the thrust levers back into the TOGA detent. Tower then switched us over to Center. After contacting Center and with the terrain warning finally over; the FO called for and I completed the climb sequence and after t/o checklist. Once everything was stabilized; both the FO and I discussed at length what happened. We were both in agreement that we experienced an erroneous terrain warning. My RA continued to have the yellow bar and still showed -5 feet until about 10-15 minutes or 20;000 to 30;00 feet into the flight. The FO indicated he thought his RA was faulty as well. Once we landed and were at the gate in ZZZ; I wrote up the terrain warning and the faulty RA and I called Maintenance control. They had me run the RA test and returned the aircraft back into service. The controller told me that this can happen when the aircraft taxis on icy and snow covered runways/taxi-ways/ramps. After letting the controller know we had been on the ground in ZZZ for over two hours with those conditions; he was confident that's what caused our issues. He said when the ice and snow melts off the RA antennas; the RA returns back to normal. The subsequent flight to ZZZ2 was normal. I thought about this event and I'm not sure if I'm supposed to send in an ASAP; but I finally thought it might be a good idea. Please contact me if you have any questions or need more data. I believe the RA's functioned abnormally due to their antenna's prolonged exposure to snowy and icy conditions on the runway; taxiway; and ramp at ZZZ airport. I suggest an advisory could be sent out to keep the crews from being startled when this occurs in the conditions explained above. However; remind the aircrews to still comply with the terrain warning; whether it's an erroneous warning or not.




Synopsis: ERJ-175 Captain reported erroneous EGPWS terrain warning during departure from a mountainous airport departure. Flight crew conducted a CFIT profile and completed an uneventful flight to destination where maintenance attributed the warning to the RA antenna icing.