Over the years, if I have been worried about the time of departure of a plane from a given airport at which it has not yet arrived, I have asked the AC agent if the plane has left the previous airport or is in transit to the current airport- if so, at what time will the plane arrive at the airport at which I am waiting.

Most of the time the agents have given me this information. However, when I was in Las Vegas a few weeks ago, I was waiting for the plane which would depart to YVR; the agent could not give me any information on the plane which was still in flight from YYC. She told me that the AC agents do not have the capability of tracking arriving planes.