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|
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 |
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.