Originally Posted by
xliioper
Delta Pro site (pro.delta.com) policy for Travel Agency Partners (which presumably also applies to DL) says flights must be delayed by at least 120 minutes for free schedule change and airport must be within 100 mile radius in order for an airport change. LAN would qualify for DTW, but GRR and AZO would not.
I’ve had success changing to nearby airports for changes of a lot less than 2 hours. Even for one minute the online change flight has worked for $0 upcharge.