B747 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
ATC Issue All Types; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Weather / Turbulence
Flight Crew Returned To Clearance
ATC Equipment / Nav Facility / Buildings; Procedure
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.
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.