Certainly part of the assault on Skyfall Lodge, I'd say. Remains to be see whether it's the actual helicopter attack, or other explosions and fighting around it, but won't be far off. Seems like it must be quite a long attack, if this is shot in daylight and it continues into nighttime. Very excited to see it!
Just looked a bit closer at the clapperboard. There's a label "Day for Dusk", so it appears that the attack must begin in early evening and continue into the hours of darkness.
They only applied for one night shoot, didn't they? Doubt they'd do much action stuff if it's only one night.