FlightXML2 returning empty filed_ete for some flights

A customer of mine contacted me about an error they were seeing in my app, which uses the FlightXML2 API. This was not the usual complaint about incorrect flight data or times, but an actual server error (generated by my server).

I investigated further, and discovered that the data returned for VS43 has a blank filed_ete field for one of the flights. I have not seen this before, and my code threw an exception since the filed_ete was not in a format that it can use.

I have since adjusted my code to catch this error and discard flights with bad data like this, but it seems to me that FlightXML2 should not be returning empty values for filed_ete. Can you please investigate? An excerpt from the JSON returned by your API for the problematic response from /FlightInfoEx is included below:

URL: flightxml.flightaware.com/json/F … ident=VS43

Partial response:
{“FlightInfoExResult”:{“next_offset”:15,“flights”:{“faFlightID”:“VIR43-1419858599-adhoc-0”,“ident”:“VIR43”,“aircrafttype”:“B744”,“filed_ete”:“”,“filed_time”:1419858599,“filed_departuretime”:1419858599,“filed_airspeed_kts”:0,“filed_airspeed_mach”:“”,“filed_altitude”:0,“route”:“”,“actualdeparturetime”:-1,“estimatedarrivaltime”:-1,“actualarrivaltime”:-1,“diverted”:“”,“origin”:“EGKK”,“destination”:“KLAS”,“originName”:“London Gatwick”,“originCity”:“London, England”,“destinationName”:“McCarran Intl”,“destinationCity”:“Las Vegas, NV”}]}}

Some of the flights that we track do not have full flightplan information provided to us, so we can only provide the fields that we know. (Notice that many of the filed_* elements are also blank/zero.)

That particular flight was an unscheduled flight that was operated because the earlier flight in the day had an emergency diversion and the passengers needed to be flown on a special flight operated later in the day.

Thanks for the clarification Jeff. I do hope that FlightAware can sanitize this data more in the future - it’s a lot of validation guesswork to handle on our side when we don’t know which fields can be relied upon to be present and complete. It’s also a bummer when flights can’t be displayed to customers because the data is incomplete - a flight with 0 duration has to be treated basically like corrupt data by our flight tracker. How come some of the flight plans are complete while others are not, for the same ident? Doesn’t the airline / FAA follow the same procedure even when filing an unscheduled flight? I’d appreciate some clarification of the underlying cause of erroneous / incomplete records? Is it human error as a result of manual data entry, or something else?

As I mentioned, that flight in particular was special because it was not a regularly scheduled flight and no prior knowledge of it was available. It was in fact first discovered by FlightAware while in the air (so-called “Ad hoc” flight) without even knowledge of its intended destination, which would have initially shown as a blank destination. Eventually some of the additional fields were discovered when it entered U.S. airspace, such as the intended destination.

Due to improvements in technology, we now track an increasing number of flights that are “ad hoc” (or “position only”) flights that would have otherwise been completely absent from our system before. These flights do not represent “bad data” or an error, but in fact just represent a flight where incomplete information is available.