Oakland oceanic controller reported an airborne conflict when an aircraft descended to a non turbule...

Narrative:

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 controller in charge (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.

Original NASA ASRS Text

Title: Oakland Oceanic Controller reported an airborne conflict when an aircraft descended to a non turbulent altitude through the protected airspace of another aircraft.

Narrative: 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.

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	1609411
Time
Date	201901
Local Time Of Day	0601-1200
Place
Locale Reference	ZOA.ARTCC
State Reference	CA
Aircraft 1
Make Model Name	B737-800
Flight Phase	Cruise
Flight Plan	IFR
Aircraft 2
Make Model Name	B747-400
Flight Phase	Cruise
Flight Plan	IFR
Person 1
Function	Enroute
Qualification	Air Traffic Control Fully Certified
Events
Anomaly	ATC Issue All Types Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy Deviation - Track / Heading All Types Inflight Event / Encounter Weather / Turbulence

Oakland oceanic controller reported an airborne conflict when an aircraft descended to a non turbulent altitude through the protected airspace of another aircraft.