Thanks for the info. The Delta website shows DL#4936 - ORD to DTW departing at 10:35 AM on 7/28. Putting DL#4936 in the Google search box shows DL#4936 as ATL to IAD at 4:00 PM. I know flight numbers change and times change as well. The Flight Tracker app has always displayed the changes. In fact, I've often noticed the change there when the flight numbers "gray" out, indicating that it is no longer a valid flight as listed.