Date: 202007
Local time of day: 1201-1800
Location: ZZZ.ARTCC, US
Flight conditions: VMC
Light: Daylight
Aircraft: Regional Jet 900 (CRJ900)
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Climb
Airspace: Class E ZZZ
ATC / advisory: Center ZZZ
Second aircraft: Any Unknown or Unlisted Aircraft Manufacturer
Aircraft component: Traffic Collision Avoidance System (TCAS)
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Human factors: Time Pressure; Situational Awareness; Communication Breakdown
Anomaly: ATC Issue All Types; Aircraft Equipment Problem Less Severe; Conflict Airborne Conflict; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Automation Aircraft TA; Person Flight Crew
When detected: In-flight
Result: Flight Crew Took Evasive Action; Flight Crew FLC Overrode Automation
Contributing factors: Aircraft; ATC Equipment / Nav Facility / Buildings
Primary problem: Ambiguous

Narrative: During climb; passing approximately 7;000 ft. heading 020 as assigned by ATC; I observed a target on the TCAS display at our 11 to 12 o'clock position approaching our position from above and descending. I queried ATC to ask if they still wanted us on the 020 heading. As the controller responded 'affirmative' the TCAS target became a yellow TA; and very quickly became an RA with a 'Climb' command; with the green shade of the VSI narrowly at the top of the indicator. The Captain began a climb; however shallowed the climb soon after. I called to the Captain's attention that the TCAS was commanding a climb; and the Captain replied I have the traffic in sight and that it was above us and appearing to climb. I then observed what appeared to be a flight of two single engine propeller airplanes in formation above our position and in a steep climb. It was obvious that complying with the climb command; and placing the vertical speed in the green range would have seriously jeopardized the safety of the flight. The TCAS announced 'Clear of Conflict' and I notified ATC that we had responded to a TCAS RA. I first detected the event when I observed the target on my TCAS display. It was approaching our position from approx. 12 o'clock; and descending towards our altitude. Realizing there was a potential conflict; I asked ATC if they still wanted us on our current heading (020 deg). As the controller responded 'affirmative'; the target became a yellow TA; and very quickly an RA with a climb command was generated. When the traffic above us passed; I noticed that they appeared to be single engine propeller airplanes; possibly vintage fighter aircraft. I suspect this because of not only their shape; but also because they appeared to me to be moving very fast; and climbing steeply. It is possible that those aircraft did not have TCAS systems installed; leaving our TCAS system to send a one sided command. This is; of course; speculation; but one possibility in explaining why they were climbing while our TCAS commanded us to do the same. As for why the flight of 2 aircraft could not be heard on the frequency; or why the controller appeared not to see them; I am not sure.The climb command placed the green shade near vertically at the top. When I called this to the attention of the Captain; the reply was I can see the traffic and did not think it would be safe to climb. When I observed the traffic; apparently in a climb; it was clear to both of us that pitching the airplane up that high; and into the green shade at the top of the VSI; would have pointed our aircraft directly at the conflicting traffic; and therefore would have jeopardized the safe outcome of the flight.In retrospect; I believe I could have been more direct with ATC sooner. I should have stated clearly that I observed traffic at out 12 o' clock and descending. If the controller was able to see the two aircraft in radar; he may have been able to issue instructions to both our flight and the flight of 2.




Synopsis: CRJ900 First Officer reported possible TCAS RA error.