We’ve been using FlightXML2 for the past few years to query schedules and departure/arrival info for recent flights. Recently the API started not finding some common flights or returning incorrect, seemingly random data. One recent example is about the flight THY7735. This is a regular daily flight that doesn’t even appear on the website (https://flightaware.com/live/flight/THY7735). When queried for the scheduled flight through the API for the 30th June 2020, we receive some data: TK17735 30Jun FRA/SAW 14:05-18:05. Note that the scheduled departure/arrival times are 13.45cet - 17.45 UTC+3, so they are off by 20 minutes. Also the returned flight code is 17735, not 7735. There is no flight with the number TK17735.
Please note that this is not an individual / intermittent incident, I have been receiving frequent reports of such inconsistencies, with departure/arrival times are sometimes off by many hours.
Any help is appreciated,