B747 pilot reported deviating from assigned track on his overwater flight under control of tokyo cen...

Narrative:

We were at FL350 on a very dark night. I spotted a thunderstorm buildup about 80 miles ahead and requested deviation up to 10 miles left using controller/pilot data link communications (cpdlc) from tokyo center. No response was received by the time we were about 15 miles from the buildup. I decided in the interest of safety to deviate as necessary to the left; notified ATC; turned on lights; etc. When we were about 10 miles left of course; rjjj approved our deviation. Shortly thereafter we were suddenly in another buildup and had to immediately deviate 5 more miles left. We again [advised ATC] and deviated another 5 miles left of course; at which time rjjj again approved our deviation. The system was too slow to respond to our urgent operational needs to protect the flight.

Original NASA ASRS Text

Title: B747 pilot reported deviating from assigned track on his overwater flight under control of Tokyo Center when he encountered weather and Tokyo was slow to respond with a clearance to deviate.

Narrative: We were at FL350 on a very dark night. I spotted a thunderstorm buildup about 80 miles ahead and requested deviation up to 10 miles left using Controller/Pilot Data Link Communications (CPDLC) from Tokyo Center. No response was received by the time we were about 15 miles from the buildup. I decided in the interest of safety to deviate as necessary to the left; notified ATC; turned on lights; etc. When we were about 10 miles left of course; RJJJ approved our deviation. Shortly thereafter we were suddenly in another buildup and had to immediately deviate 5 more miles left. We again [advised ATC] and deviated another 5 miles left of course; at which time RJJJ again approved our deviation. The system was too slow to respond to our urgent operational needs to protect the flight.

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	1287542
Time
Date	201508
Place
Locale Reference	RJJJ.ARTCC
State Reference	FO
Aircraft 1
Make Model Name	B747 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Person 1
Function	Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	ATC Issue All Types Deviation - Procedural Clearance Deviation - Track / Heading All Types Inflight Event / Encounter Weather / Turbulence

B747 pilot reported deviating from assigned track on his overwater flight under control of tokyo center when he encountered weather and tokyo was slow to respond with a clearance to deviate.