Knowing reasons for change of a flight's course

Good Morning,

We are currently extracting flight position data (among others) through the firehose API for some downstream processing. From the data obtained, we can see that each flight (e.g., UA 277 from IAD to SFO) naturally follows a certain flight path under normal conditions. However, there are times when the flight takes a different course possibly due to adverse weather conditions or any other factors. All we know from the data coming from firehose is a change in position (through lat and lon) but we do not know the reasons why a flight may changed its course from a routine one to something different.

Does anyone know if this extra information related to reasons for change of course can be known through firehose or aeroapi or some other means? Any response would be appreciated.

Thanks in advance,

The reason for a flight route’s change is not provided in any electronic form.

However, you can try monitoring the flightplan messsage’s “route” element to observe when changes are issued and apply some heuristics. If a change occurs prior to flight departure, then the reason was obviously known in advance (likely weather planning). If a change occurs after flight departure, then it is might be either congestion or weather, if the route becomes longer. If the route becomes shorter after flight departure, it is probably just due to normal flight optimizations (“shortcuts”) offered by ATC.