Same route, same December weather: Delta cancelled 12.9% of its LaGuardia–Chicago flights, American 1.1%

Both airlines flew LaGuardia–O'Hare through the same storms. The gap wasn't the sky: 30 of Delta's 40 cancellations on the route were coded to the airline's own operations; every one of American's was coded weather — per the carriers' own filings with the Department of Transportation.