Why are some FR24 arrival estimates bodgy?

[Melburnian1]

Flightradar24.com - Live flight tracker! and its similar competitors use amazing technology. Overall it's an excellent service to meeters and greeters, travellers and aviation enthusiasts. It is also fun to watch.

That said, on occasion even when flights have 'levelled out', the information on it can seemingly be wrong, even in developed countries like Oz where there is presumably sufficient information being fed back to the website.

A case in point is Saturday 30 October's QF1504. The website records that this flight is timetabled ex HBA at 1330 hours but took off at 1402, yet with 336 kilometres to go and the plane flying at an indicated speed of 735 kilometres an hour (398 knots), the site tries to suggest that the flight will be in Melbourne at 1448 (in 23 minutes.)

However a flight that is quite a deal ahead of it, JQ702, is also shown as 'due' in MEL at an identical time - 1448.

Both cannot be correct.

In contrast, the Melbourne Airport - Flight Information, Shopping & Parking site predicts that the QF flight will be in at 1504.

Why do these errors persist? I realise that sometimes the arrival times have to be recalculated (and this may be a 'dynamic' process) but surely commonsense tells us that when the JQ flight is about 183 kilometres closer to MEL than the QF one (in this case), that simultaneous arrival is not jolly likely.

 

[mannej]

Flightradar24.com - Live flight tracker! and its similar competitors use amazing technology. Overall it's an excellent service to meeters and greeters, travellers and aviation enthusiasts. It is also fun to watch.

That said, on occasion even when flights have 'levelled out', the information on it can seemingly be wrong, even in developed countries like Oz where there is presumably sufficient information being fed back to the website.

A case in point is Saturday 30 October's QF1504. The website records that this flight is timetabled ex HBA at 1330 hours but took off at 1402, yet with 336 kilometres to go and the plane flying at an indicated speed of 735 kilometres an hour (398 knots), the site tries to suggest that the flight will be in Melbourne at 1448 (in 23 minutes.)

However a flight that is quite a deal ahead of it, JQ702, is also shown as 'due' in MEL at an identical time - 1448.

Both cannot be correct.

In contrast, the Melbourne Airport - Flight Information, Shopping & Parking site predicts that the QF flight will be in at 1504.

Why do these errors persist? I realise that sometimes the arrival times have to be recalculated (and this may be a 'dynamic' process) but surely commonsense tells us that when the JQ flight is about 183 kilometres closer to MEL than the QF one (in this case), that simultaneous arrival is not jolly likely.

Why don't you "Ask the Pilot" as the information may be coming from the flight deck itself instead of being an estimate of the software?

 

[Boris spatsky]

The site uses 3 feeds to my knowledge. ACARS off blocks time (sent by the plane at pushback), flight plan ETA and ATC radar/ADS-B info. Various things can alter/affect all of those - and it is only a guide anyway (that is, it's not an aviation certified feed hence the accuracy may be lax at best).

 

[Melburnian1]

Thank you gents. Very helpful, although, Boris spatsky, quite often the information displayed turns out to be close to 100 per cent correct. I was picking out what statisticians might call an 'outlier.'

 

[Boris spatsky]

Yes it can be accurate too. It seems to be worst when outside radar coverage, although it can be pretty bad on short sectors from SYD too sometimes! I think ACARS confuses it. The aircraft tells ACARS an off the bay time and a separate takeoff time but i have seen instances where FR24 has clearly used the wrong one to determine the ETA.

The ETA function also can't factor in holding so as soon as you get that, the ETA goes out the window...

 

[Melburnian1]

Thank you Boris. Simple, clear explanation that even I can understand.