Hmmm... I've lived in a place that received around 500 inches of snow per year. If that snow did not melt (it did where I lived, thankfully) and if compressed to 10 percent of its original depth to account for lost interstitial volume, we arrive at an ice depth of around 4 feet. At four feet of accumulation per year for the intervening 60 or so years, the resulting figure is quite close to the 250 feet you've mentioned. I guess I've missed your point.
You've missed the point alright. Show us where Greenland gets 500" of snow a year, especially at the exact spot where the planes landed.
Then perhaps, you could explain why they traveled a mile from their original location.