Aircraft display problem

[andbur]

ADS-B - evaluation of transponder data

I have carfully watched the problems of these wrongly indicating positions.

Actually waht happens is - obviously this (new) software is doing "dead reckoning" on its targets for some seconds. This means, for a certain time frame the position of the aircraft is calculated by the speed and track / heading given by the ADS-B transponder.

However - there is on little problem. As to the ADS-B specifications somea ircraft are equipped with "weight off wheel" switches. So landing, when the weight is on - or until take-off, when the weight goes off - some functions of the transponder can be disabled. This may differ from aircraft to aircraft - it is not even type specific. The aircraft watched - showing the symtoms reported - all showed their last speed prior touchdown and the tracks whilst taxiing. Ergo ....

The position and speed are not coming from the same aircraft systam - and - it is not necessarily GPS tha supplies the position to the transponder. See FAR 91 and the respective TSO's.

The software developers will only have two possibiliteis to solve this problem. Either turn off the "dead reckoning" function - or - include an algorythm in the sofware to calculate the mean speed between the last reported positions.

By the way - the digital radar systems as used by ATC normaly use a similar sofware. Radar positions sometimes tend to "jump". The software calculates the postion on bases of dead reckoning and overlays with the measured last positions of the aircraft (mostly 4 to 8 - depending on the system). The different set up = multiradar, precision of the radar(s) used, flight altitudes - grade the different positions and show the most probable one on the dispays.

A similar system is used for navigation. E.g. differential GPS uses the short term precision of a platform (INS) and the long term precision of a GPS to calculate and display a position. Why is GPS called precise only long term and nor short term- very simple - specificall when an aircraft is changing pitch and or attitude the signals from some Satellites may be shielded off. As pitch and bank are mainly used to perform departure and arrival - during approach - using GPS only - the GPS system alone is not qualified to perform precision approaches.

Lets see how it is solved.

Greetings

Andreas

[cretanrunner]

Speedbird, many thanks for that. Nice to know it's not my PC playing up.

Is there any indication, however crude, as to how long the changeover will take to complete? (A really annoying question, I know....)

Andrew

[speedbird1960]

We will all have to be patient as Flightradar24 changes over to the new feeder software, there are bound to be some teething problems.

It affects the Database updater's more than anyone as what we see on the map is not always reliable and sometimes i have to do Playback several times on different days to confirm that route is correct.

Flightradar24 has improved massively since it first started and sometimes bugs do affect the Aircraft on the Map when changes are made.

[cretanrunner]

Thanks Ralph. I guess we'll just have to wait a while. It's just annoying watching icons shooting around erratically!

Andrew

[controller]

Hello Andrew,

Iīm sorry I do not have any other information. Normaly Mike answers these problems fast, it seems to bee more difficult.

I took off my upload until problem is solved.

Ralph

[cretanrunner]

Hi Controller
Is there any more information about this display problem? I still have the strange plane icon behaviour.

Andrew

[controller]

Hy Andrew,

you are on my mind.

Maybe now Mike has to make a statement, all other things would be speculation.

Ralph

[cretanrunner]

Thanks to everyone, but I'm still none the wiser...... The technical stuff is all way over my head, and obviously it does not help if parts of threads have been deleted. Can anyone just tell me whether this is a known problem that is being worked on, or what exactly is the status?

My display is definitely behaving strangely, and I would just like to know whether there is anything I can do about it, or whether someone is working on a bug fix.

Andrew

[controller]

Hy,

seems that Mike or any other ADMIN has removed some questions because of posting in the wrong thread.

Arthur had a questions about T-F4V.

I have the original posting from him but I donīt know if the ADMIN allows to repost a deleted thread ?

So I can only post my answer :

Hello Arthur,

I donīt think that there is a static delay of five minutes. I think that the Data is collected in a central database and then send to fr24 as T-F4V. Thats because of the delay.

It varies in my area from 1-3 Minutes, thats why I have here jumping planes. Iīm wondering that they are not able to have clear data using the timestamp ?


Hope this posting will no be deleted.

Ralph

[cretanrunner]

Thanks, that is similar to the behaviour I'm getting. I see a post from "Mike" saying that the old database will be turned off and the problem should go away. He said this would happen in 2 - 3 weeks, but that was 8 weeks ago. Anyone know why we still have the problem, or is it just me?

[jedthebass]

cretanrunner,take a look here http://forum.flightradar24.com/threa...7961#post17961 This is Controllers post on this subject.

[cretanrunner]

Hi all

Could someone please point me to the other threads mentioned in Controller's post, where I might get a fix for these problems. I'm suffering the same symptoms as the OP. (or rather my system is.....). I'm new to the forum, and although I have searched, I cannot find any answers.

Thanks.

[j_balwani]

Hi Friends,

I'm new to this forum but I m using Flight Radar 24 since November 2011. I'm very glad to see radar T-F4V which cover Mumbai Airport (VABB/BOM) since its my home town, but what I have observed is the data is not correct. This radar is not working like any other radars and its not providing us with the correct information. The airplane is displayed on short final and stays there for few seconds and then moves backwards and stays there. I really can't see airplanes departing and landing and following the actual route. I don't know if I have bought up this matter at correct place or not but would like to know about this radar.

I am also glad to see radar T-VIDP1 and its working fine so far

Thank you

[controller]

Hy,

yes, I tested the F4V Data also.

One screenshot of courious route I reported also. Right now I took my feed offline in order to see how Data will look like.

I think there is maybe en echo of the Data because planes jump forward and backward with same feeder (F4V).

Ralph

[Oblivian]

I have a screenshot of a flight at 2,345,444,200ft off the end of the runway at work from when a F4V took over