Widebody Transport
Flight Crew Air Transport Pilot (ATP)
Flight Crew Total 12468; Flight Crew Type 9464
Human-Machine Interface; Confusion
ATC Issue All Types; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued New Clearance; Flight Crew Requested ATC Assistance / Clarification
Procedure; Human Factors
We just crossed 45N40 on our oceanic clearance FL380. The next waypoints on our current clearance is 41N30; FATMO and AMAKR. At XA:13; we received a CPDLC reroute message from SFO:/CLEAREDROUTE CLEARANCEARRIVAL:BDEGA2.AMAKRAMAKRWe printed the message and selected the load prompt on the FMC. We compared the printed message with the FMC; but failed to notice that 41N30 and FATMO were deleted. Upon accepting the message and executing the FMC; the aircraft immediately turned direct to AMAKR. After a short discussion with the other pilot we heading selected back to the original course towards 41N30; then rebuilt our FMC Legs Page to 41N30 FATMO AMAKR BDEGA2 arrival. We called SFO ARINC on HF to clarify our clearance; ARINC said they would ask SFO Center. No immediate response then from ARINC.At XA:20; we received a CPDLC message from SFO:/DESCEND TO REACH FL370 BY XA:25/REPORT LEVEL FL370/FOR TRAFFIC. I NEEDED YOU DIRECT AMAKRWe printed; accepted and complied with this message:At XA:26; we sent a CPDLC message back to SFO:/YOUR RTE CLEARANCE WAS AMBIGUOUS. DID NOT SAY DIRECT AMAKR. ONLY SPECIFIED ARRIVAL-BDEGA2.AMAK (could not complete our message due to character limitations for the CPDLC free text).
Reporter confirmed that they accepted the message clearance since it appeared to be only an arrival procedure clearance and did not include the words 'REVISED RTE' or 'DIRECT AMAKR'.
[Report narrative contained no additional information.]
Air carrier flight crew reported an improperly worded CPDLC reroute from ATC on an oceanic flight.