ZLA controller describes a climb clearance given to an aircraft and the aircraft's climb rate change...

Attributes
ACN	1197342
Time
Date	201408
Local Time Of Day	1801-2400
Place
Locale Reference	ZLA.ARTCC
State Reference	CA
Environment
Light	Dusk
Aircraft 1
Make Model Name	Large Transport
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Aircraft 2
Make Model Name	Medium Transport Low Wing 2 Turboprop Eng
Operating Under FAR Part	Part 121
Flight Phase	Climb
Flight Plan	IFR
Person 1
Function	Enroute
Qualification	Air Traffic Control Fully Certified
Experience	Air Traffic Control Time Certified In Pos 1 (yrs) 19
Events
Anomaly	Conflict Airborne Conflict Deviation - Procedural Published Material / Policy

Narrative:

Aircraft X was 40 miles west of bld VOR at FL330 requesting FL350. Aircraft Y was 40 miles northeast of bld VOR at FL340 requesting FL360. Both aircraft were inbound to bld VOR. I issued climb clearance to aircraft X to FL340 and shortly thereafter; I issued a climb clearance to aircraft Y to FL360. I observed aircraft Y mode C at FL350; and issued a climb clearance to aircraft X to FL350. Both aircraft were over 30 miles apart converging to bld VOR. I noticed aircraft Y mode C level at FL355 and inquired to pilot if he was climbing. He advised he was and informed me that his last 500 feet would be a less than standard climb. I issued traffic to both aircraft. Aircraft Y advised he had traffic in sight and aircraft X said he was responding to a TCAS event. I acknowledged.

Original NASA ASRS Text

Title: ZLA Controller describes a climb clearance given to an aircraft and the aircraft's climb rate changes the last 500 feet causing another aircraft to have an RA and the Controller to have a loss of separation.

Narrative: Aircraft X was 40 miles west of BLD VOR at FL330 requesting FL350. Aircraft Y was 40 miles NE of BLD VOR at FL340 requesting FL360. Both aircraft were inbound to BLD VOR. I issued climb clearance to Aircraft X to FL340 and shortly thereafter; I issued a climb clearance to Aircraft Y to FL360. I observed Aircraft Y Mode C at FL350; and issued a climb clearance to Aircraft X to FL350. Both aircraft were over 30 miles apart converging to BLD VOR. I noticed Aircraft Y Mode C level at FL355 and inquired to pilot if he was climbing. He advised he was and informed me that his last 500 feet would be a less than standard climb. I issued traffic to both aircraft. Aircraft Y advised he had traffic in sight and Aircraft X said he was responding to a TCAS event. I acknowledged.

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.

ZLA controller describes a climb clearance given to an aircraft and the aircraft's climb rate changes the last 500 feet causing another aircraft to have an RA and the controller to have a loss of separation.