Flight Tracker Differences

[SpringHeeledJack]

Since I begrudgingly entered the 'smart' device world, one of the first apps I added was the 'plane finder' app, as the FR24 apps pricing structure was too convoluted. In the main it's been fine, satisfying the "I wonder what that is" reflex. However, in the last while I've noticed that helicopter and non-scheduled aircraft often don't show, despite showing up on both FR24 and Planefinder on the laptop. Any ideas chaps ?

[DaveReidUK]

All flight tracking apps use data that aircraft transmit with details of their position, altitude, etc. But they can only use that data if their respective networks of enthusiasts with receivers has someone within range of the aircraft in question (competing networks don't share data, as a rule). So that accounts for some of the differences between networks.

The other main variation is in how each network copes (or doesn't) with aircraft that don't explicitly send their location. It's still possible to plot them using a technique called multilateration, but the way each network implements that (or not) is different - some are better at it than others, and some don't bother at all.

Aircraft that fall into the latter category typically include helicopters, GA and older passenger aircraft. That probably accounts for the differences that you're seeing.

[KelvinD]

I more or less switched from FR24 to Planefinder one day in February 2014; a dull, miserable day with a good handful of spotters waiting at the sharp end of 27L in anticipation of the Etihad A330 in purple livery (A6-AFA). It was late arriving and slightly delayed with the departure. Departure was getting ever closer to 15:00 and everybody was getting nervous it wasn't going to make the runway switch over and off they all rushed to 27R. I was about to go as there was nothing showing on FR24 when the only other person still there said it was lining up. I looked again at FR24 and that end of the runway was showing nothing. He showed me his Planefinder app and there it was, along with a couple of others so I stayed put and caught it departing (my photo was timed at 15:00:06!
While scratching my head over what was the difference between the 2 apps, I came to the conclusion that it was all down to how many feeds were supplying the app and it seemed to me that Planefinder just had either better or more feeds at that time. Even now, there are times when I can't see an aircraft on the ground on one app so I will switch to see if it appears on the other (and often it does).
Sometimes unscheduled aircraft don't show until the aircraft is almost on approach. Good examples of this at Heathrow recently have been Qatar Executive Gulfstream G650, A7-CGB and various Middle Eastern Royal Flights.
In other cases when an aircraft fails to show on either app, it can be down to the aircraft being new and not having the reg updated in the relevant database.
As for the helicopters, I don't have a clue! Just now I can see a couple of Bristows and another coming out of Inverness. At other times, around Heathrow, I have seen Police helicopters appearing at times, and disappearing at others.
The nice thing about Planefinder is the use of filters. This way, if I am lurking around Heathrow I use a filter to ensure all I see are flights heading for Heathrow, rather than the thousands that would otherwise show. This falls down though when the new reg or non-scheduled service appears. If the flight data doesn't show LHR as a destination, it won't appear. Sometimes if I see a suspiciously large gap between a couple of inbound flights, I will switch off the filter and, like magic, an unscheduled aircraft will appear in the gap.

[El Bunto]

despite showing up on both FR24 and Planefinder on the laptop. Any ideas chaps ?

I don't think the question has been addressed yet. I too have seen differences between the FR24 website and app at the same time.

It seems that the app is less generous in plotting the predicted track of aircraft that are no longer being actively received or MLATted; I think the website does it for an hour or more but the app will elide them much quicker.

Also, check your FR24 general app settings. It seems to have much more aggressive defaults that appear to be intended to minimise battery consumption but in doing so can hide certain types or categories of traffic.

[HEATHROW DIRECTOR]

I'm far from being a computer genius but how much memory do the small devices have compared to a desktop PC? Could be relevant?

[treadigraph]

While walking on Sunday a light aircraft zotted past just out of visual i/d range which didn't show up on Planefinder on my smart phone; it is visible on the replay on my laptop - Monsun G-AYPE.

ADSB Exchange is pretty good for military as well, though there is no replay facility I can discover!

[DaveReidUK]

While walking on Sunday a light aircraft zotted past just out of visual i/d range which didn't show up on Planefinder on my smart phone; it is visible on the replay on my laptop - Monsun G-AYPE.

That's a good example - the aircraft in question doesn't transmit its location, so any plots you see on the PlaneFinder map have been derived by multilateration.

It may be that those types of plot aren't visible in real-time, but only on a replay.

[treadigraph]

MLAT are usually visible in real time on my laptop ('PE is often out and about), just not on my smart phone - signal strength wasn't great possibly a factor. I'll try and some comparisons tomorrow if the weather is reasonable! I am rather bored at work presently!

[SpringHeeledJack]

Thanks for the replies, the tracker world is full of conundrums it would seem. Even adsbexchange seems to not show as much as it once did, perhaps operators are unwilling to let uninvolved persons track them in near real time ? I'm not sure I'd be happy for my private movements to be tracked (says the man with a smart phone!) were I to be a high worth individual. Having looked on the Apple App Store, there are many other trackers apart from Planefinder and FR24, but I'm surmising that they'd only have the same raw data and perhaps fewer 'feeders, so less accuracy.

[treadigraph]

Foggy clag in Croydon - horizontal vis about half a mile, top of Saffron Square (43 stories) is visible.

Quick comparison between laptop and smartphone shows exactly the same info. Not many light aircraft around right now, except for a German Malibu which I hope just landed safely at Biggin. Cross checking on FR24 showed it to be MLAT.

Looked like it might have broken off the 21 ILS and flown the circuit to land on 03 instead. Must have been fun as I imagine the weather is much the same at Biggin as it is here. Very light winds, 21 is possibly marginally downwind.

[DaveReidUK]

Even adsbexchange seems to not show as much as it once did, perhaps operators are unwilling to let uninvolved persons track them in near real time ? I'm not sure I'd be happy for my private movements to be tracked (says the man with a smart phone!) were I to be a high worth individual.

That's been the case even before the advent of all the enthusiast tracking sites. The radar feed which the FAA have made available to industry for many years has always had provision for corporate operators to suppress details of their aircraft's movements, mainly because of the commercial sensitivity.

Some tracking sites, for example FlightRadar24, provide the same facility. From the FR24 FAQ:

"For private aircraft, we can block flight tracking information at the owners request"

Some other sites and apps, such as PlanePlotter, don't as far as I'm aware.