# What date and time definition is used for the second leg of a flight?

Let's take flight BA0015, from London to Syndney, via Singapore. This is data from FlightStats.

The first leg has this data:

  "carrierFsCode":"BA",
"flightNumber":"15",
"departureAirportFsCode":"LHR",
"arrivalAirportFsCode":"SIN",
"departureDate":{
"dateUtc":"2019-08-17T20:30:00Z",
"dateLocal":"2019-08-17T21:30:00"
},
"arrivalDate":{
"dateUtc":"2019-08-18T09:45:00Z",
"dateLocal":"2019-08-18T17:45:00"
},


It takes off from London, on 2019-08-17 at 20:30 UTC and lands in Singapore, on 2019-08-18 at 09:45 UTC

but then the second leg:

  "carrierFsCode":"BA",
"flightNumber":"15",
"departureAirportFsCode":"SIN",
"arrivalAirportFsCode":"SYD",
"departureDate":{
"dateUtc":"2019-08-17T11:25:00Z",
"dateLocal":"2019-08-17T19:25:00"
},
"arrivalDate":{
"dateUtc":"2019-08-17T19:10:00Z",
"dateLocal":"2019-08-18T05:10:00"
},


It takes off, in the past, from Singapore on 2019-08-17 at 11:25 and lands in Sydney on 2019-08-17 at 19:10.

Is is possible that the day doesn't get incremented because the second leg still belongs to the same flight code?

• At a guess, it looks like you've asked it to show you the BA15 flight on August 17. It just so happens that there are 2 BA15 departures each day, the earliest (in GMT) is from Singapore and the later one is from London. If you asked for it to display departures on the 18th you would see the Singapore departure, linked to the first flight you've posted here. Is that what your question is about? – Ben Aug 20 '19 at 2:52

You are looking at two different planes.

This is the flight from London to Singapore, which departed on 17th of August, on flightaware.com: The dates and times are local, meaning the flight departed 2019-08-17T21:11:00Z (UTC) and landed 2019-08-18T10:23:00Z.

Before this flight even took off, another 777 departed Singapore headed for Sydney: The flight departed 2019-08-17T11:56:00Z and landed 2019-08-17T19:09:00Z.

The plane which landed in Singapore on the 18th of August also continued to Sydney later that day:

• ok, so on that day there is the departure flight (LHX->SIN), and the arrival of the previous flight (SIN->SYD), while I was expecting the API to return me one flight LHX->SIN->SYD with its 2 legs. I see now, using the connecting Ids I didn't include in my question that this is indeed two flights. I was under the assumption that there wouldn't be more than a single flight in a day window (00:00-23:59) flying under the same code, but in this case we can see there are 2: leg1 from the flight of that day, and leg2 from the flight of the previous day. – Thomas Aug 20 '19 at 9:17
• @Thomas Exactly, they are allowed to use the same flight number multiple times per day, although the ATC callsigns must be unique (see this question). – Bianfable Aug 20 '19 at 9:25