A B787 captain left the flight station for short break and upon return noted the aircraft climbing t...

Narrative:

Climb from FL390 to FL410 possible altitude deviation.I was on lavatory break returning to the cockpit thus not on the flight deck as the aircraft left FL390 for FL410. When I initially called for re-entry to the cockpit while awaiting the flight attendant to set up the cart for 'blocking' via interphone. My first officer asked if I wanted to climb to the FMC recommended FL410; it was my leg. I said yes it was smooth. It took a minute or two to set up the door 'block'. As I entered at approximately 38;900 feet ATC asked 'who cleared you to 410?' he then cleared us to fl 410 in the same transmission there was no traffic conflict that we were aware of I noted the time as approximately xa:27.I inquired with ATC if we needed to contact anybody about 'this' since I was clear the 41;000 feet was in the 'altitude' window and did not think my first officer would have put it there without a 'clearance' to do so. Controller stated that they were researching the tapes and querying the controller about a possible controller pilot data link communication (cpdlc) clearance being issued they might not be aware of. It was curious that the controller knew and stated we were going to 41;000 verses 'why are you in a climb' or 'say altitude'. My thought at the time is he may not be sure if he or did or didn't already clear us. I realize the automatic detective surveillance (ads) lets him see the 'altitude' window.

Original NASA ASRS Text

Title: A B787 Captain left the flight station for short break and upon return noted the aircraft climbing to FL410 from FL390. Uncertain about the clearance; he inquired and was then cleared to FL410.

Narrative: Climb from FL390 to FL410 possible altitude deviation.I was on lavatory break returning to the cockpit thus not on the flight deck as the aircraft left FL390 for FL410. When I initially called for re-entry to the cockpit while awaiting the flight attendant to set up the cart for 'blocking' via interphone. My First Officer asked if I wanted to climb to the FMC recommended FL410; it was my leg. I said yes it was smooth. It took a minute or two to set up the door 'block'. As I entered at approximately 38;900 feet ATC asked 'who cleared you to 410?' He then cleared us to FL 410 in the same transmission there was no traffic conflict that we were aware of I noted the time as approximately XA:27.I inquired with ATC if we needed to contact anybody about 'this' since I was clear the 41;000 feet was in the 'ALT' window and did not think my First Officer would have put it there without a 'clearance' to do so. Controller stated that they were researching the tapes and querying the Controller about a possible Controller Pilot Data Link Communication (CPDLC) clearance being issued they might not be aware of. It was curious that the Controller knew and stated we were going to 41;000 verses 'why are you in a climb' or 'say altitude'. My thought at the time is he may not be sure if he or did or didn't already clear us. I realize the Automatic Detective Surveillance (ADS) lets him see the 'ALT' window.

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	1292016
Time
Date	201508
Local Time Of Day	0601-1200
Place
Locale Reference	ZOA.ARTCC
State Reference	CA
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	B787 Dreamliner Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Route In Use	Oceanic
Flight Plan	IFR
Person 1
Function	Captain
Experience	Flight Crew Last 90 Days 200 Flight Crew Total 15865 Flight Crew Type 1272
Events
Anomaly	ATC Issue All Types Deviation - Altitude Excursion From Assigned Altitude Deviation - Altitude Overshoot Deviation - Procedural Clearance Deviation - Procedural FAR

A B787 captain left the flight station for short break and upon return noted the aircraft climbing to FL410 from FL390. Uncertain about the clearance; he inquired and was then cleared to FL410.