Never mind missing burn marks. Wavelength (distance between peaks) of an 60 Hz AC power waveform is on the order of 2000 to 3000 miles.
Yes but that has no bearing on msbbarratt's calculations. I checked them and his (her?) numbers are correct. The distance between what look like burn marks corresponds to peaks of an AC cycle at the speed the aircraft would be flying. The peaks are where you'd get the worst arcing.