ZLA controllers reported believing they had handed off an aircraft to the adjacent ARTCC; but the ha...

Narrative:

I was training a developmental. We had a radar assist with little experience. The radar controller at sector 33 has very little experience and they were training on his assist side at d-33. Sec 32's airspace starts at 34000 feet. D-33 flashes aircraft X to us out of 150 climbing and somehow either my developmental or our d-side takes the handoff that early. After a couple minutes the radar controller at sector 33 says he would just keep aircraft X because he was climbing so slow and we just accepted a point out climbing to 35000 feet. We never flashed aircraft X back to sector 33. Sector 33 climbs aircraft X to 35000 feet and after a few minutes ships him to ZLC 44 because he thought they had radar contact with him. Neither me; my trainee; nor assist controller realized we still had control of the data block. Aircraft X then starts to conflict alert flash with a las arrival coming from ZLC 44 at 32000 feet. Aircraft X was still climbing out of 28000 feet and the data block still reflected he was climbing to 35000 feet right into the las arrival. Not I; the developmental; or the assist questioned the radar controller at sector 33; because we all assumed that sector 33 was taking care of it. After aircraft X was 4 miles into ZLC 44's airspace and still climbing out of 29000 feet; ZLC 44 called our assist and said that they were talking to aircraft X and they stopped him below the las arrival. There were a lot of things that went wrong in this situation. Lack of experience has a lot to do with this. I should have realized that we still had control of the data block and had my developmental either handoff back to sector 33 or handoff to ZLC 44. I was always trained not to assume anything in this job. I assumed that sector 33 was taking care of traffic in their airspace without questioning. The auto handoff flash must not have worked to ZLC 44 or this wouldn't have happened. ZLC 44 should have called sector 33 when aircraft X checked on their frequency or sent him back to sector 33 and none of this would have happened. There was a lack of teamwork everywhere and it all could have been avoided.

Original NASA ASRS Text

Title: ZLA controllers reported believing they had handed off an aircraft to the adjacent ARTCC; but the handoff had not been completed. The adjacent Center Controller had to restrict the aircraft's climb for opposite direction traffic.

Narrative: I was training a developmental. We had a radar assist with little experience. The radar controller at sector 33 has very little experience and they were training on his assist side at d-33. Sec 32's airspace starts at 34000 feet. D-33 flashes Aircraft X to us out of 150 climbing and somehow either my developmental or our d-side takes the handoff that early. After a couple minutes the radar controller at sector 33 says he would just keep Aircraft X because he was climbing so slow and we just accepted a point out climbing to 35000 feet. We never flashed Aircraft X back to sector 33. Sector 33 climbs Aircraft X to 35000 feet and after a few minutes ships him to ZLC 44 because he thought they had radar contact with him. Neither me; my trainee; nor assist controller realized we still had control of the data block. Aircraft X then starts to conflict alert flash with a LAS arrival coming from ZLC 44 at 32000 feet. Aircraft X was still climbing out of 28000 feet and the data block still reflected he was climbing to 35000 feet right into the LAS arrival. Not I; the developmental; or the assist questioned the radar controller at sector 33; because we all assumed that sector 33 was taking care of it. After Aircraft X was 4 miles into ZLC 44's airspace and still climbing out of 29000 feet; ZLC 44 called our assist and said that they were talking to Aircraft X and they stopped him below the LAS arrival. There were a lot of things that went wrong in this situation. Lack of experience has a lot to do with this. I should have realized that we still had control of the data block and had my developmental either handoff back to sector 33 or handoff to ZLC 44. I was always trained not to assume anything in this job. I assumed that sector 33 was taking care of traffic in their airspace without questioning. The auto handoff flash must not have worked to ZLC 44 or this wouldn't have happened. ZLC 44 should have called sector 33 when Aircraft X checked on their frequency or sent him back to sector 33 and none of this would have happened. There was a lack of teamwork everywhere and it all could have been avoided.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	1362439
Time
Date	201606
Local Time Of Day	1801-2400
Place
Locale Reference	ZLA.ARTCC
State Reference	CA
Environment
Light	Daylight
Aircraft 1
Make Model Name	Large Transport Low Wing 2 Turbojet Eng
Operating Under FAR Part	Part 121
Flight Phase	Climb
Flight Plan	IFR
Person 1
Function	Instructor Enroute
Qualification	Air Traffic Control Fully Certified
Experience	Air Traffic Control Time Certified In Pos 1 (yrs) 16
Person 2
Function	Trainee Enroute
Qualification	Air Traffic Control Developmental
Experience	Air Traffic Control Time Certified In Pos 1 (yrs) 0
Events
Anomaly	ATC Issue All Types Airspace Violation All Types Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy

ZLA controllers reported believing they had handed off an aircraft to the adjacent ARTCC; but the handoff had not been completed. The adjacent center controller had to restrict the aircraft's climb for opposite direction traffic.