B747 flight crew describes the use of cpdlc to request deviations around convective weather in the c...

Narrative:

Flight under cpdlc [controller pilot data link communication]. When I was awakened from crew rest for over water crew change; I took first officer's seat with captain still in his seat (about to go on break) flying. Crew had already requested and received clearance to deviate left or right of course for an extensive area of convective wx. We agreed clearance insufficient to avoid all echoes; so requested additional latitude; before this clearance could be received the immediate need for additional leeway arose. Declared emergency using cpdlc. Aircraft may or may not have exceeded lateral limits of deviation clearance; am filing this report now just in case it did. Ultimately; ATC asked if we desired a revised clearance; and we responded in the affirmative. Revised clearance obtained; was loaded into FMC; and flight proceeded normally from this point. Turbulence never did quite reach 'moderate' level; as it turned out. However; seat belt sign was on throughout this encounter and F/a's were seated by PA from cockpit. So far as I recall; flight conducted in accordance with SOP/far/etc in all respects.

Original NASA ASRS Text

Title: B747 flight crew describes the use of CPDLC to request deviations around convective weather in the central pacific. An emergency is declared when further deviation is required prior to receiving a second clearance via CPDLC.

Narrative: Flight under CPDLC [Controller Pilot Data Link Communication]. When I was awakened from crew rest for over water crew change; I took F/O's seat with Captain still in his seat (about to go on break) flying. Crew had already requested and received clearance to deviate left or right of course for an extensive area of convective wx. We agreed clearance insufficient to avoid all echoes; so requested additional latitude; before this clearance could be received the immediate need for additional leeway arose. Declared emergency using CPDLC. Aircraft may or may not have exceeded lateral limits of deviation clearance; am filing this report now just in case it did. Ultimately; ATC asked if we desired a revised clearance; and we responded in the affirmative. Revised clearance obtained; was loaded into FMC; and flight proceeded normally from this point. Turbulence never did quite reach 'Moderate' level; as it turned out. However; seat belt sign was on throughout this encounter and F/A's were seated by PA from cockpit. So far as I recall; flight conducted in accordance with SOP/FAR/etc in all respects.

Data retrieved from NASA's ASRS site as of April 2012 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	962732
Time
Date	201108
Local Time Of Day	0001-0600
Place
Locale Reference	ZOA.ARTCC
State Reference	CA
Aircraft 1
Make Model Name	B747-400
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Person 1
Function	Pilot Not Flying First Officer
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 150 Flight Crew Total 21000 Flight Crew Type 4000
Person 2
Function	Captain Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 210 Flight Crew Total 23000 Flight Crew Type 8500
Events
Anomaly	Deviation - Track / Heading All Types Inflight Event / Encounter Weather / Turbulence

B747 flight crew describes the use of cpdlc to request deviations around convective weather in the central pacific. An emergency is declared when further deviation is required prior to receiving a second clearance via cpdlc.