Widebody transport flight crew reported an altitude overshoot occurred when the crew was distracted by a smoking oven event in the galley and a wake vortex encounter.
Synopsis
Widebody transport flight crew reported an altitude overshoot occurred when the crew was distracted by a smoking oven event in the galley and a wake vortex encounter.
Narrative
After a normal takeoff and initial climb out; we were climbing through 7500ft with a clearance to level at 11;000ft. The center seat Relief Pilot took a Cabin Call. The Aft Galley Flight Attendant was reporting that one of the ovens was emitting heavy smoke and fumes and they were assessing the situation and would call us back. At this point I turned the Autopilot ON and began thinking ahead to my actions should this situation deteriorate into a full blown emergency. The Flight attendants called back at about 10000 ft and were speaking to the Relief Pilot when we began to encounter heavy wake turbulence from the proceeding 787. At one point the aircraft rolled about 15 to 20 degrees to the left along with turbulence shaking consistent with a wake turbulence encounter. I instinctively disengaged the autopilot and began making more aggressive control inputs to counter the roll while increasing our rate of climb to try and get out of the wake turbulence. As I increased the rate of climb the wake effects became worse. I then heard the Altitude Alert warning sound and the selected altitude illuminated in amber and realized we had climbed above our cleared altitude of 11;.000 and were at 11;500. I immediately took corrective action and descended back to 11;000ft. ATC did ask us to confirm our altitude which at that point was back level at 11;000ft. We had experienced an altitude deviation but had no loss of separation on aircraft near us. The situation with the oven in the galley resolved and was determined to be spilled food smoking. The Flight attendants turned the oven off and pulled the CB (Circuit Breaker) and reported that the smoke was dissipating rapidly.Once above FL 180 we debriefed the departure and altitude event. We identified that the potential emergency in the cabin and the wake turbulence encounter were both significant distractions that lead to the altitude deviation. The center Relief Pilot was tasked with communicating with the Flight Attendants about the Smoke/Fumes event when we encountered the wake and was somewhat out of the loop dealing with that. The Second Relief Pilot was not in a good position to observe the instruments. The pilot monitoring FO noticed the altitude deviation about the same time I did when we heard the aural warning and saw the PFD (Primary Flight Display) amber indications and by that time we were already correcting. We discussed that a Check Path Altitude was not used; but again the center Relief Pilot was tasked with the FAs. Had we noticed the deviation earlier we would have used it. As for what I may do next time I wish I had not disengaged the autopilot as it would have leveled at 11000. It wasn't so much a decision to do so; as an instinctive reaction to the rapid rolling of the aircraft. In hindsight the autopilot was handling the wake effects and likely would have remained engaged. Also instead of trying to climb out of the wake; we discussed that a lateral turn would have been a better option. I think these are good takeaways but things I did not think of in the heat of battle in a task saturating situation.
Second reporter narrative
Passing through 9000 ft on our way to 11000 ft; there was a report of smoke in the aft galley. The PF immediately put the A/P (Autopilot) on as we waited for further information from the back. Passing through 10500; I began pulling up the EFB and the FAs called back with information that the smoke was dissipating but they were still working on the source. Around this time; we got into aggressive wake turbulence while in a right hand turn to AMAKER and the airplane pitched left. The PF disconnected the A/P pilot to gain control of the A/C (Aircraft) and stopped the level off to get above the wake. I looked up from what I was doing in the box just as the altitude alert went off that we past our altitude. The PF recognized the error and smoothly recovered to our assigned altitude of 11000. The autopilot was engaged and Oakland was informed we had hit wake turbulence as we were trying to level off which caused us to be high.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.