B737-800
Air Traffic Control Fully Certified
Situational Awareness
ATC Issue All Types; Deviation - Altitude Excursion From Assigned Altitude; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Provided Assistance
Weather; Human Factors
I was the controller of Ocean Sectors 4 and 7. I had the three aircraft; Aircraft X; Aircraft Y; [and] Aircraft Z at flight level 360; 350 and 340 respectively. Aircraft Y had requested a climb to FL370 due to continuous moderate turbulence at FL350. Due to his traffic of Aircraft X at FL360; I informed the Aircraft Y unable higher and possible higher after XA47Z. A few minutes later at XA32Z I received an APR (Aircraft Position Report) message informing me that Aircraft X was not at his assigned altitude of FL360 but at FL342. At this time I also received a CPDLC message informing me that Aircraft X was descending to FL300 due to a rough ride. Noticing this I called the CIC (Controller in Charge) over for assistance. As he was already through Aircraft Y's altitude; when I probed his descent; it was probing green. Thus I probed the block FL300B360 and it indicated a conflict with Aircraft Y at FL350 as well as Aircraft X at FL340. I did not get the time for the Aircraft X conflict start time as the initial probe for the descent starting from above his altitude showed green; this indicated to me that the probe for the block was a loss going to happen with 30 minutes but not happening at this time. Aircraft Y was in conflict at that time and a loss of separation had occurred with his descent. We sent out a message to Aircraft X to say reason for descent without clearance. At this time subsequent APR's showed Aircraft X to be off his route as well; VHF weather deviation to protect his probing profile. He then sent a message that he had declared PAN and descended to FL300 with a 15nm offset; on top of that planning to climb to return to FL360. As we had an ADS [Automatic Dependent Surveillance] hit confirming he was at FL300; we EALT [Emergency Altitude] FL300 to his profile. We sent CPDLC message to Aircraft X Negative; maintain FL300; of which he responded with Wilco. Due to the message queue expanding beyond 30 messages at this point; I asked to split sector 7; of which the incident was contained in; and remained to catch up with sector 4. No change; pilot initiated deviation of cleared altitude.
Oakland Oceanic Controller reported an airborne conflict when an aircraft descended to a non turbulent altitude through the protected airspace of another aircraft.