A problem with airlines since time immemorial. Once, a long time ago, I was flying DTW-PHL on NW at Christmas to visit my parents. The inbound flight was fogged in at MSP, so I called my parents to say don't leave for the airport until I call and say I have an ETD. Once the plane arrived and was almost ready to board, I called back and my dad said, "Your mom and Dee (my sister) left three hours ago because the girl on the phone said you had left Detroit." This at a time when the plane hadn't even left MSP yet.