Heavy Transport; Low Wing; 4 Turbojet Eng
Air Traffic Control Developmental
Communication Breakdown; Confusion
Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Provided Assistance; Air Traffic Control Separated Traffic
Procedure
Aircraft X was coordinated with New York Ocean Sector D16 at F360.  Just prior to the New York/Piarco boundary the aircraft logged onto his data-link ADS/CPDLC and the aircraft reported at FL380.  The pilot reported via HF over BUTUX a few minutes later at F360.  I sent an on-demand request to the aircraft and the ADS confirmed F380.  I send an altitude confirmation message to the pilot via HF and the pilot confirmed at FL380; different than his last report at FL360.  I called Piarco Center and confirmed what they showed for the altitude clearance for Aircraft X; and they responded with FL360.  I told the pilot I showed him cleared to FL360; I re-cleared the aircraft to maintain FL380 (there was no traffic); and asked how long the aircraft was at FL380.  The pilot responded that they were issued a clearance by Dakar Center (GOOO) to climb to FL380.  I passed this information to Piarco Center and they contacted DAKAR Center; who responded that they didn't issue the climb clearance; and actually confirmed at Aircraft X was at F360.  Further investigation is being performed.  Aircraft X flew through Piarco's airspace; and entered NY airspace at FL380 when the flight was believed to be cleared to and maintaining FL360.  I did not have any traffic at FL360 or FL380 and Piarco said they didn't have any traffic at FL380 for the flight.  It does not appear any loss of separation occurred.  Shortly after entering NY airspace at an altitude other than what was expected; the fight was re-cleared to maintain FL380 and the aircraft's profile was updated and accurate.  This appears to be a pilot deviation; climb without a clearance.  The only notification that there was a problem was because the aircraft logged onto ADS/CPDLC.  Since the aircraft reported entering NY airspace at BUTUX at FL360 originally; if I never received an ADS report at FL380 I would have never known the aircraft was not at the expected altitude.  Piarco Center does not have ADS/CPDLC capability; and I am unsure if Dakar center (GOOO) has that capability.  Since the pilot was voice reporting FL360 via HF; Piarco was unaware of the discrepancy.Piarco center could gain ADS/CPDLC ability to better conformance check the aircraft's cleared profile with information that comes directly from the FMS of the aircraft vs. relying on HF voice reports.
ZNY Controller reports of an aircraft that was not at the altitude it was supposed to be at.