Date: 202011
Local time of day: 1801-2400
Location: ZZZ.Tower, US
Flight conditions: VMC
Light: Night
Aircraft: Regional Jet 900 (CRJ900)
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Final Approach
Airspace: Class B ZZZ
ATC / advisory: Tower ZZZ
Second aircraft: Helicopter
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Human factors: Distraction; Situational Awareness; Time Pressure; Workload
Second reporter function: Pilot Flying; First Officer
Anomaly: Conflict NMAC; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Automation Aircraft RA; Automation Aircraft TA; Person Air Traffic Control; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Flight Crew Requested ATC Assistance / Clarification; Flight Crew FLC complied w / Automation / Advisory; Flight Crew Took Evasive Action
Contributing factors: Company Policy; Human Factors; Procedure
Primary problem: Procedure

Narrative: After a diversion to our planned alternate we had a routine enroute and descent phase. We contacted Tower on about a 10 mile final. We were approximately 5 miles in trail of a B737; and we heard them check in as well. I overheard tower tell them about a Medevac helicopter who was operating to the east of the airport and transiting to the west. Once we were on about a 5 mile final; tower provided us with a traffic call for the same helicopter. The first call we received was traffic at our 10 o'clock and about three miles; and that the traffic had us in sight and was maintaining visual separation. Due to the lights of the city; I did not see the traffic; and it was not yet showing up on our TCAS.Inside of a 4 mile final; at approximately 1200 ft. we received a Traffic Alert for the traffic. On TCAS it showed him at 200 ft. above us and inside a mile. I immediately saw the traffic visually and told the first officer that I had the traffic in sight. Based on the traffic's track and altitude; I very quickly suspected that we might receive an RA. I instructed the first officer to go slightly below the glide slope to increase our separation. Very shortly after that; at 1050 ft. we received a 'DESCEND DESCEND' TCAS Resolution Alert. The First Officer followed the TCAS guidance and I informed ATC. Due to the switch at 1000 ft. to Traffic Alert only we never received a clear of conflict; but we were able to visually identify that we were clear of conflict at about 800 ft. We were one dot low on the glide slope but correcting and all other approach criteria were stable so I quickly asked the First Officer if he felt stable. He responded that he did; so we agreed that we were okay to continue the approach. At our closest point; the helicopter was directly above us and approximately 200 ft. above; leading to a significantly reduced margin of separation.This event was caused by several factors. The helicopter pilot had us in sight and was maintaining visual separation; but in our opinion; the separation provided was not adequate. I was not able to visually identify the traffic until the Traffic Alert occurred; and at that point there was very little we could do to avoid a loss of separation. I do not believe we should have been sequenced by air traffic control to pass directly underneath the medevac's flight path. After landing I communicated my concerns to tower and he said that once the helicopter reported maintaining Visual Separation; he had no further responsibility to separate us. If that is correct; I believe it is a fundamentally unsafe procedure. In this event it led to us receiving a descending RA at 1000 ft. leaving us with very little maneuvering room. I should have made more of an effort to find the traffic prior to receiving a Traffic Alert; but with the city lights it was difficult. This was at the end of a very high workload; 3 hour blocked flight with significant weather; holding; a diversion; and fuel considerations. I believe that this type of event could have been prevented with better planning from air traffic control. There was clearly a difference in expectations between the helicopter pilot and us; and the helicopter pilot may have been comfortable with 200 ft. of separation; but we were not.


Second narrative: We diverted due to weather. On final approach we received a TCAS Resolution Alert due to a medical helicopter crossing the final approach. I was Pilot Flying for the approach. When we received the Traffic Alert; I initially assumed it was an aircraft on a parallel approach. The Pilot Monitoring reported the aircraft in sight. The helicopter had also reported us in sight. Only moments before the Resolution Alert did I realize the aircraft was going to cross directly in front. We received a descending Resolution Alert. I complied with the Resolution Alert. The helicopter passed approximately 200 ft. above. I don't recall ever hearing a clear of conflict call. We descended below 1000 ft. and the TCAS went into Traffic Alert Only mode.A medical helicopter was crossing approximately 3 mile final at approximately 1200 ft. while we were on approach. I was manually flying a challenging approach due to high winds and did not recognize the threat until a few seconds before the Resolution Alert.


Synopsis: CRJ900 flight crew reported 200 ft. of separation with a helicopter on approach.