Flight crew departing IAD experienced a simultaneous false Terrain Alert and false TCAS/RA advisory.
Synopsis
Flight crew departing IAD experienced a simultaneous false Terrain Alert and false TCAS/RA advisory.
Narrative
After taking off; we received a 'Too Low Terrain' and a yellow flashing RA on our screens. Terrain page was up and there was nothing but green dots and black on our page. At first I thought we may have been upside down or something because we were in the clouds and there was a B767 that departed not too long after. The PFD confirmed we were straight and level which is why I didn't overreact. MFD showed no red dots or anything that may have posed a terrain threat. After landing in ZZZ; I spoke to Pilot on Duty; and he said he's never seen that before. We both looked up 5G interference in the FOM; and there was no maintenance write up required per FOM. We also confirmed 5G NOTAMS were in NOT in effect so we determined 5G Interference would not be possible. We were also flying an aircraft with Load XX.Y. I thought it may have been that. With no certainty as to what the issue was; I did not know how to address it properly; and I did not document it in the maintenance log. It came to my attention a few days after the incident report was submitted; I should have submitted a report as well. Speak to Maintenance in situations like this; not just the Duty Pilot.
Second reporter narrative
Upon takeoff out of Dulles around 500 ft. we received a too low terrain as well an flashing RA. We had a positive rate of climb and the Captain and I both had our terrain page up. We had a positive rate of climb and we couldn't have been going towards any sort of terrain. Upon reaching cruising altitude we both discussed what could have caused this issue. We both thought it was either a load issue or 5G interference. My Captain notified ATC that we had potentially had a 5G interference. Upon landing and getting to the gate my Captain called the Duty Pilot who said we did not have to fill out an incident or other report. The flight after that issue was uneventful and we landed in ZZZ without any problems
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.