Unusual number of errors Sunday 17.02 at GVA airport

Sunday 17.02 at GVA airport (ICAO LSGG) an unusual number of errors in the announcement of the delay was observed by one of our client who was on site

I only have one example to show you but my client had a lot more error than abit and he could not use our app to work.

SWR359 
Scheduled: 09h35 
Effective arrival (observed at GVA): 13h39
Estimate arrival (by flight XML): 12h44 

Was there a particular incident that day?

The scheduled and observed times for SWR359 on 2019-02-17 are inline with GVA’s timezone being at UTC+1 and FlightXML results being stated in UTC. Were the client’s other observed time differences also approximately an hour? If the client was expecting localized times this could explain a consistent observed difference.

That’s true for this example. Thanks for your answer!

Excuse me but I coming back on this issue after more investigations:

Finally my time zone conversion is right.

At 11:15:03 I recieved a “departure” event with:
“actualdeparturetime”:1550402090,
“estimatedarrivaltime”:1550403890,
“short_desc”:“SWR359 (BCS3) parti de LHR @ 11:14AM GMT pour GVA Heure d’arrivée estimée 12:44PM CET”

actualdeparturetime => 1550402090 = 2019-02-17 11:14:50 UTC = 2019-02-17 12:14:50 at GVA airport
estimatedarrivaltime => 1550403890 = 2019-02-17 11:44:50 UTC = 2019-02-17 12:44:50 at GVA airport

This estimated arrival time looks very optimist (30 minutes for a LHR > GVA).

I understand the difficulty of making accurate estimates all the time. But I need to know if I should warn my client that this situation will happen often.

In most cases, the estimated times are simply what is provided to us by either the airline, operator, or ATC, and we do not usually have any control over the accuracy/inaccuracy of those timestamps.