Isn’t the acceleration here just the difference in velocity between the plane and the runway so 0.7 m/s/s?

IF the velocity would change from 0.7m/s to 0m/s over one second, the acceleration would be 0.7m/s/s. But if the time span over which that velocity change is (much) shorter, the acceleration would be (much) higher.

	▲	adgjlsfhk1 5 hours ago \| parent [-]
		Is it much shorter? An airplane does take a while to settle down. You land tail first and the nose generally takes a second or so to come down.