Date: 201512
Local time of day: 1801-2400
Location: ZID.ARTCC, IN
Light: Daylight
Aircraft: Medium Large Transport; Low Wing; 2 Turbojet Eng
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Descent
Airspace: Class A ZID
ATC / advisory: Center ZID
Second aircraft: Light Transport; Low Wing; 2 Turbojet Eng
Reporter organization: Government
Reporter function: Enroute
Reporter qualification: Air Traffic Control Developmental
Human factors: Training / Qualification; Situational Awareness; Confusion; Workload
Anomaly: ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Weather / Turbulence
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Air Traffic Control Separated Traffic
Contributing factors: Human Factors; Weather
Primary problem: Human Factors

Narrative: Aircraft X was northbound. The rides were choppy 27000 feet and above. Aircraft X came over at 34000 feet asked for lower altitude due to the bad rides. I descended it to 26000 feet. About 6 to 8 minutes later Aircraft Y came over level at 30000 feet. Aircraft Y asked for a lower altitude.  I looked for traffic; saw Aircraft X was at 26000 feet; and descended the Aircraft Y to 27000 feet. They started Conflict Alert flashing on the screen; and I realized that I had misread Aircraft X datablock; that it was still descending and was only at 29500 feet or so. I then amended Aircraft Y to 29000 feet. I thought that Aircraft X would be below 28000 feet before Aircraft Y got to 29000 feet; and I was wrong. On the replay; Aircraft X was at 28400 feet and was 4.73 miles laterally from Aircraft Y at 29000 feet. Aircraft X descended at the minimum rate all the way from 34000 feet and I did not ask him to increase the rate of descent; and I also felt pressured to start Aircraft Y down because of the bad rides they were experiencing. There are several holes in the cheese that lined up to lead to this loss of separation. I as the Radar Controller take full responsibility of the loss; but feel that I should never have been put in that situation in the first place. I feel management dropped the ball and allowed a situation to develop that escalated to a loss of separation. I am a developmental and have been certified on the high altitude sectors but not the low altitude sectors. I am currently training on the lows and spend almost all of my time there. Even though I am certified on the high sectors; and I am not nearly as proficient as I was when I earned the certification. I probably have the least amount of radar hours on the high sectors in the area; because I am always training on the low sectors. I think it should be mandatory for developmentals to work at least one day a week on the radar positions that they have already certified on. That way they don't lose their proficiency while they are training on the other sectors.  Secondly; management is told that the dangerous time periods for people include right before they leave and go on holidays. This loss occurred half hour before I went home. Thirdly; I had been training all day; but my trainer went home one hour early; so I was left in a position where I needed to stay an extra hour at work without my trainer. I was mentally exhausted from training for 5 days; was working my 3rd day shift in a row; had probably built up some sleep debt; and was ready to go home for a nice weekend. Fourthly; a Radar Assist only person was put on my sector and this worker is still very shy and afraid to speak up. I thought it was a rule that only Certified Controllers could be on my Radar Assist for a certain amount of time after I checked out. I have no doubt that if I had any other person that had been at work at that time on my Radar Assist; they would have seen my error and helped me correct it in a timely manner; and avoiding the loss of separation. The combination of those things is what led to this loss of separation. I recommend that if management is going to let a developmental work a sector that they are very not proficient at; that at the very least a Certified Controller only is on their Radar Assist. I also recommend that the Supervisor take into account where the person is in their schedule and it is a mistake to let that person work radar as opposed to doing last minute Computer Based Instruction; or assigned to a Radar Assist to end their day.




Synopsis: An aircraft was descending from 34000 feet to 26000 feet. The Controller descended another aircraft from 30000 feet to 27000 feet. The aircraft were opposite direction with less than five miles lateral separation. When the Controller descended the second aircraft from 30000 feet the first aircraft was at 29500 feet descending.