Tracking estimated arrival time

Hi,

I am calculating the delayed time for flights using the estimated_arrival_time and filed_departure_time.

i noticed that sometimes (30% of the time) the estimated_arrival_time gets updated and then revert back to the original (usually within 5 minutes)
which will give me a wrong delayed time.
the status will be like this:
On time => delayed => on time

what is the proper way to keep track of the estimated_arrival_time? How do i ensure that the estimated_arrival_time will not give me a fake delayed time?

thanks,
Ivan

All data fields will potentially change as we get more recent information about a flight. Sometimes the new information may change or conflict with information reflected by prior messages.

In some cases we can detect and ignore obviously bogus information supplied by one of our providers, and sometimes we are able to calculate our own ETA values (such as when the flight is enroute) when our algorithms have greater confidence than our upstream providers. However, in most cases FlightAware is simply providing you with the latest information that is being given us.