For the photo and avgeeks out there reading this, airfields are extremely dark at night; this is especially true for Dulles since the runways are so far away from the ramp's sodium lights. All landing photos on the runway were at ISO 25,600, f/2.8, 1/125th in order to have just enough shutter speed to stop motion, but still have enough light to make the capture, and I still had to boost exposure by +⅔EV in post. The 1D X handles these kinds of conditions very well; extraordinarily well for press usage as is the purpose here.
Photos on the ramp were at ISO 12,800, f/2.8, 1/250th, mainly because I am photographing while walking during water arches; the ramps are lit by orange sodium lights which can be counteracted with manual White Balance set to 2,100K; this setting shifts their amber light white, but will shift the 4,300K incandescent bulbs illuminating the Main Terminal a deep cyan. You can see this same effect in my inaugural photos for Brussels Airlines, and a few of my weddings and portrait sessions where I purposely use this mixed-color-temperature situation for dramatic effect.
Departure photos were at a more sensible ISO 6,400, f/2.8, 1/60th. In general I won't drop my shutter speeds below 1/125th unless dark lighting conditions or creative need arises, and I usually prefer to stay at 1/250th and above if I can help it without going crazy with the ISOs. That said, I'm not afraid of pushing into high-ISO because I know the 1D X handles them very well (although this post isn't the best example of it).