ZLA D-Side Controller described operational error when R-Side Controller failed to take timely action to prevent the developing loss of separation; reporter listing lack of experience and Supervisor oversight as causal factors.
Synopsis
ZLA D-Side Controller described operational error when R-Side Controller failed to take timely action to prevent the developing loss of separation; reporter listing lack of experience and Supervisor oversight as causal factors.
Narrative
The R-side was sequencing several aircraft into Los Angeles. Controller Y had Aircraft X level at FL340 and needing to lose about a minute in time. He took RADAR on Aircraft Y direct EED. Aircraft Y was turned early to EED putting the plane right through all of Sec 39's planes over TNP. The R-side turned Aircraft X 20 degrees right for spacing. This also took the plane away from Aircraft Y. Both planes were still separated. Sec 40 then handed off another plane headed direct BLD VORTAC which was in direct conflict with an LAX arrival. The R-side had the LAX arrival expedite. This was not going to work so I coordinated off line with Sec 40 to stop their plane at FL350; stopping our plane at FL360. At about this time the R-side turned Aircraft X back to the left of course and descended the plane. I did not hear him do this. When I noticed the plane turning left and descending I told the R-side to turn the planes. He turned Aircraft Y 20 degrees to the right and asked Aircraft X to expedite. This was not enough and the two airplanes lost separation. The R-side was a new CPC. He fell behind in his sequencing and had the airplanes too high. Sec 40 complicated the situation by sending planes through the congested part of the sector rather than leaving them on course. When he descended Aircraft X he didn't see the Aircraft Y. Recommendation; there was an inexperienced R-side who was falling way behind. There was a CPC with only a couple of years experience working Sec 40 who was making matters worse for Sec 39. I was verbally coordinating with Sec 40 about the direct BLD being in conflict with one of out planes. I feel the supervisor who was in the room just 10 feet away should have come over to see what was going on. Perhaps another set of eyes and ears would have noticed when the R-side descended the Aircraft X.
Second reporter narrative
I had a moderate work load for sequencing into LAX; about 8 or 9 arrivals. Sector 40 sent Aircraft Y direct EED across the LAX flow. I had vectored Aircraft X for additional spacing. As this was going on another incident was working between SKW4512 in sector 40 going direct BLD and another LAX arrival direct to KONZL on the SEAVU2 arrival. While I was solving that conflict I gave Aircraft X a descent to FL240 and cleared him back to KONZL. By the time conflict alert had gone off and made me aware that I had forgotten about Aircraft Y; the aircraft were already too close to save the deal; however I was able to vector both aircraft and keep the targets from merging.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.