Narrative:

Level in smooth air at FL380 and just over 5 hours into the flight; the aircraft lurched similar to impending turbulence. I turned on the seat belt sign. A few seconds later we had an EICAS message 'spoilers'. We could feel a yaw to the right and found the #10 spoiler indicator blank on the flight control systems page.I continued as pilot flying and the first officer (first officer) ran the irregular check list. We woke a first officer relief pilot and asked them to visually verify the position of the third spoiler on the right wing (#10). Relief first officer reported that that the spoiler was indeed deployed. Secondary indications were autopilot correction inputs of 2.5 right rudder and slight left aileron.once stabilized; we contacted dispatch and asked to include [maintenance] in our conversation. [Maintenance] verified that we indeed had a problem with spoiler #10 and that its circuit breaker had tripped. There was no inflight 'fix'.dispatch conferred with ATC and recommended we continue to ZZZ for a quick lockdown of the defective spoiler; deferral; refuel and continue to destination. We noticed an increased fuel flow and deployed spoiler buffet. We asked dispatch and [maintenance] if they had data of the increased fuel flow effect on range. They stated that they did not have this data.by this time all pilots were back in the cockpit. The four of us reviewed available options. Consensus was that if we continued to ZZZ as recommended by dispatch and not knowing what our fuel burn would be; that it would be less safe than turning back. We informed dispatch that we felt safer turning back. We then requested from center a clearance direct to ZZZ1. Dispatch sent us up a flight plan present position direct to ZZZ1; it showed slightly over 4 hours back to ZZZ1 with a landing fuel of 47.6. On our alternates page ZZZ was showing to be nearly 5 hours with marginal enroute alternate.as a crew we reviewed guidelines for declaring emergency. We felt that without further systems degrade; declaring emergency was not warranted. We were asked several times by ATC if we were declaring emergency; we declined.we landed uneventfully in ZZZ1 and blocked in with fuel of aprox 40.5. Attributing most of the aprox 7;000 lbs over burn (vs the flight plan) to the deployed spoiler.good communication was maintained throughout the flight with dispatch; ATC; flight attendants and passengers.

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Original NASA ASRS Text

Title: B787 flight crew reported uncommanded spoiler deployment in-flight resulting in diversion.

Narrative: Level in smooth air at FL380 and just over 5 hours into the flight; the aircraft lurched similar to impending turbulence. I turned on the seat belt sign. A few seconds later we had an EICAS message 'Spoilers'. We could feel a yaw to the right and found the #10 spoiler indicator blank on the flight control systems page.I continued as pilot flying and the First Officer (FO) ran the irregular check list. We woke a FO relief pilot and asked them to visually verify the position of the third spoiler on the right wing (#10). Relief FO reported that that the spoiler was indeed deployed. Secondary indications were autopilot correction inputs of 2.5 right rudder and slight left aileron.Once stabilized; we contacted Dispatch and asked to include [Maintenance] in our conversation. [Maintenance] verified that we indeed had a problem with spoiler #10 and that its circuit breaker had tripped. There was no inflight 'fix'.Dispatch conferred with ATC and recommended we continue to ZZZ for a quick lockdown of the defective spoiler; deferral; refuel and continue to destination. We noticed an increased fuel flow and deployed spoiler buffet. We asked Dispatch and [maintenance] if they had data of the increased fuel flow effect on range. They stated that they did not have this data.By this time all pilots were back in the cockpit. The four of us reviewed available options. Consensus was that if we continued to ZZZ as recommended by Dispatch and not knowing what our fuel burn would be; that it would be less safe than turning back. We informed dispatch that we felt safer turning back. We then requested from Center a clearance direct to ZZZ1. Dispatch sent us up a flight plan present position direct to ZZZ1; it showed slightly over 4 hours back to ZZZ1 with a landing fuel of 47.6. On our Alternates page ZZZ was showing to be nearly 5 hours with marginal enroute alternate.As a crew we reviewed guidelines for declaring emergency. We felt that without further systems degrade; declaring emergency was not warranted. We were asked several times by ATC if we were declaring emergency; we declined.We landed uneventfully in ZZZ1 and blocked in with fuel of aprox 40.5. Attributing most of the aprox 7;000 lbs over burn (vs the flight plan) to the deployed spoiler.Good communication was maintained throughout the flight with Dispatch; ATC; Flight attendants and Passengers.

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.