B777-200 flight crew reported ATC failure to provide separation resulted in a NMAC.
Synopsis
B777-200 flight crew reported ATC failure to provide separation resulted in a NMAC.
Narrative
We were given a vector somewhere ZZZZZ and ZZZZZ1; speed 240 (777 transition speed through 10;000') and told to level off at 9000 (rather than descend via the ZZZZZ to 5000) and given a heading due to Traffic at 11 O'clock; 8000'; moving slow". Traffic appeared on TCAS as Proximate and continued to climb slowly at which point we became more concerned; and I said "I think he's climbing to 8500'; VFR; we need to find him". There were scattered cumulus clouds around 8000' and we could not get a visual on the Traffic. We had to depend on ATC and TCAS as we still had no visual; traffic closed to within 5 miles. Traffic became a Traffic Advisory on TCAS. I asked the Captain to request a heading and he did since this was getting worse. We got no immediate response from ATC and it was getting far too close; I thought within a couple of miles and probably closer. We also didn't know if the traffic was going to continue to climb so I initiated a climb and a turn to the south away from the traffic just seconds prior to getting a TCAS RA which instructed us to climb. The PM informed ATC that we were responding to an RA and climbing. Almost simultaneously ATC instructed us to turn north to an East/NE heading at which point I corrected the turn back to the East/NE. We climbed to approximately 10;000'; the RA resolved and the Relief Pilot attained visual out the aft right observation window and then I picked it up heading southbound. It appeared to be a low wing single engine aircraft; maybe a Piper Cherokee or similar. The PM reported an estimated 200' separation according to TCAS and that we were correcting back down to 9000'. ATC issued a new heading and altitude to resume vectors for the approach. The remainder of the approach and landing were uneventful.It is my opinion that ATC may have lost awareness of our situation - being that the original vector set us on a potential collision course. That is further supported by the fact that the Traffic continued to climb above 8000' to at least 8500' and I believe was climbing higher through our altitude. Of further concern I believe the TCAS RA should have happened much sooner. We also did not remember having heard ATC say which way the Traffic was moving; we assumed it was west - that's why I thought he'd level off at 8500' VFR altitude - perhaps that was expectation bias. We should have not assumed ATC would provide separation when it got closer and would have been wise to be more vocal about our concerns with ATC as the Proximate Traffic became a Threat - but it happened so quickly that I'm not sure we would have had time. In fact; I didn't think I had time to coordinate with the PM/Captain and reacted pro-actively before the RA and believe that provided us vertical separation."
Second reporter narrative
While descending on the ZZZZZ arrival into ZZZ we were forced to do an RA escape maneuver to avoid VFR traffic traversing the arrival. Approach called out VFR traffic at our 11 oclock climbing and moving slowly and instructed us to stop our descent at 9000. We were looking for the traffic but due to cloud cover were not able to pick him up visually. FO was PF and started slowing the descent as we approached 9000 while we were monitoring traffic on TCAS. The traffic continued climbing and FO disconnected the AP (Autopilot) and began a climb and a slight turn to the right; South; and I reported this to approach that we needed a turn for traffic avoidance. At this point approach gave us a left turn; North; to 080. Simultaneously; we got the climbing RA and I reported to approach we were responding to an RA. VFR traffic continued to climb. We reached an altitude of approximately 9800 during the escape and TCAS displayed traffic as close as 200 feet. FO finally observed the traffic off our right side as the event ended. All of this was reported to approach and they apologized about the incident and handed us off to the next controller. FO's proactive climb before the RA was prudent in the fact that even with proper response to the RA traffic still got as close as it did.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.