Narrative:

[My first officer said] 'I wasn't sure how to tell you that during your rest period in the [crew rest area]; we had an altitude deviation from an ATC assigned crossing restriction.' I asked him for the details and then thanked him for informing me of such. He was fearful [of] advising me of this event during flight because he didn't want to possibly cause a distraction in the flight deck so close to final approach and landing. The details as described by my first officer are as follows. 'We were given a clearance to cross 40 northeast of ZZZ at FL260. We entered FL260 in the MCP (mode control panel) altitude window and then entered ZZZ/-43 FL260 into the FMC (flight management computer). I added 3 miles to the clearance to give us a buffer. I got up from my seat to get something from the galley. I returned to my seat to find that we were high on path and the relief officer was fumbling around trying to make the crossing restriction. Quite frankly; I don't know what he was doing or how he got us into the state that we were in.' this is all my first officer told me about this event. As for my absence and return to my duty station. This is what I recall. I was the last crew member to take a break. I always take the last break as I want to be awake for the crossing because of re-dispatch operations and other critical duties. I instructed the relief pilot to wake me 60 to 45 minutes from destination. I was not woken as I had requested. I was woken by the sound of the galley storage door being locked by my first officer. Once I returned to the flight deck area I briefly looked at the flight instruments and noticed we were in altitude hold and a very high indicated airspeed (barber pole/vmo) which I commented on and asked my crew to remedy. I then went into the lav; went to the galley and then returned to my seat. I asked my relief pilot how things were going and he stated that 'VNAV was having trouble staying on path.' I didn't know what this meant and ask my first officer his opinion and he said 'VNAV is okay'. In the meantime my first officer briefed me on flight status; weather; fuel; whom the active center was and that we were at FL260 on the arrival as filed for. We continued into ZZZ1 airspace and continued with a normal and uneventful flight. A break down in CRM (crew resource management); SOP's and situational awareness played a major role leading up to and causing this event to occur. With respect to our tem (threat and error management) model 'C' communications is the first slice of cheese. During our flight I had a discussion with my crew about this very subject and pointed out that we should challenge one another and use effective communications. It may come as a surprise but this was my first time that I've ever been in the [crew rest area]. I do not sleep on crossings but on this particular flight I decided to take a break in the [crew rest area].

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Original NASA ASRS Text

Title: B767-300 flight crew reported an altitude deviation caused by unknown problems with VNAV and poor Crew Resource Management.

Narrative: [My First Officer said] 'I wasn't sure how to tell you that during your rest period in the [crew rest area]; we had an altitude deviation from an ATC assigned crossing restriction.' I asked him for the details and then thanked him for informing me of such. He was fearful [of] advising me of this event during flight because he didn't want to possibly cause a distraction in the flight deck so close to final approach and landing. The details as described by my First Officer are as follows. 'We were given a clearance to cross 40 NE of ZZZ at FL260. We entered FL260 in the MCP (Mode Control Panel) altitude window and then entered ZZZ/-43 FL260 into the FMC (Flight Management Computer). I added 3 miles to the clearance to give us a buffer. I got up from my seat to get something from the galley. I returned to my seat to find that we were high on path and the Relief Officer was fumbling around trying to make the crossing restriction. Quite frankly; I don't know what he was doing or how he got us into the state that we were in.' This is all my First Officer told me about this event. As for my absence and return to my duty station. This is what I recall. I was the last crew member to take a break. I always take the last break as I want to be awake for the crossing because of Re-dispatch Operations and other critical duties. I instructed the Relief Pilot to wake me 60 to 45 minutes from destination. I was not woken as I had requested. I was woken by the sound of the galley storage door being locked by my FO. Once I returned to the flight deck area I briefly looked at the flight instruments and noticed we were in Altitude Hold and a very high indicated airspeed (barber pole/VMO) which I commented on and asked my crew to remedy. I then went into the lav; went to the galley and then returned to my seat. I asked my Relief Pilot how things were going and he stated that 'VNAV was having trouble staying on path.' I didn't know what this meant and ask my First Officer his opinion and he said 'VNAV is okay'. In the meantime my First Officer briefed me on flight status; weather; fuel; whom the active Center was and that we were at FL260 on the arrival as filed for. We continued into ZZZ1 airspace and continued with a normal and uneventful flight. A break down in CRM (Crew Resource Management); SOP's and situational awareness played a major role leading up to and causing this event to occur. With respect to our TEM (Threat and Error Management) model 'C' Communications is the first slice of cheese. During our flight I had a discussion with my crew about this very subject and pointed out that we should challenge one another and use effective communications. It may come as a surprise but this was my first time that I've ever been in the [crew rest area]. I do not sleep on crossings but on this particular flight I decided to take a break in the [crew rest area].

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.