People enjoy very much to have this nice software on their mobiles , tablets and laptops either for the fun of monitoring some air traffic or to follow a flight of interest , say the one you expect your friends to arrive with . However , they most often consider it as the picture of real Air Traffic Control , as if truly holding a world-radar into their hands. And although this will hardly make any difference to the typical user , I was stunned to discover people were having a huge misconception about it driven mainly by the ever existing ignorance around Air Traffic Control (ATC) , which they do not know still what exactly does. It was mainly after the loss of flight MH370 where a number of people took part into public discussion and they were narrating incredible stories supposing that the Flightradar24 program was the main tool ATC was using , assuming that the controllers were not looking (!!) on their screens (!!!) and then were trying to discover what happened with this flight by going back to their …. Flightradar24 recordings (!!) , a think to make experts laugh !
Unfortunately people are generally enchanted by the ‘new technology’ where they assume things mainly out of their enchantment and strong imagination , rather than just clicking a bit more further to understand what the tool is offering to them and what IS NOT ! The program itself highlights where the information is coming from … and … when and what information is not used by the program . So once on the program , better have a look as well to the HOW IT WORKS (click this link and see yourself).
So allow me to make the following very important highlights :
1. Sources are some ADS-B and MLAT (Multilateration) receptions as well as FAA data – the later though intentionally not including all movements and with a delay of 5 minutes for ‘protection’ reasons. If you check thoroughly even the European traffic comes with a delay. Why ? Because the information arrives to you with the delay of the typical internet network. You do not plug into a dedicated ATC network , which is anyhow not available to the public - for obvious reasons ! ADS-B is not a radar unit , it is and on-board equipment that gathers the flight data from the Flight Management System (FMS) of an aircraft or the ‘super-autopilot’ , to make it very simple to all. ADS-B is an aircraft unit and via the Mode-S transponder it downlinks these data to any appropriate receiver on the ground. The ‘general public’ may understand it as a SMS message which the auto-pilot of the aircraft sends below. Its use was conceived initially to allow for less voice exchange transmissions between the ATC and the Cockpit. The difference is that so far , the ground infrastructure is extremely expensive to be installed and allow everywhere its use. This is why people use it up to a certain point and for … secondary reasons , hoping in the future to make it more available. But this is not the case at present (2014) .
2. Then … the ADS-B equipped aircraft with the proper Mode-S transponders to downlink the information , DO NOT INCLUDE ALL TYPES OF AICRAFT so … not all traffic is displayed . A list is provided with those types excluded by the program itself but you may also notice that some touristic aviation general traffic is never displayed, although not expressly stated in this list . Not to mention of course that there is no chance to see any non-transponder equipped traffic. So clearly this is NOT THE ATC RADR PICTURE of the daily ATC service , despite the impression made to the ‘general public’ Additionally … The program is not using real Flight Plan information . Just have a look when you select a flight . Although its passed track is displayed , the future track to follow is merely a straight line to a point considered as the ‘center’ of the destination aerodrome : this is NOT THE FLIGHT PLAN INFORMATION of this flight - obviously. Even more, if you monitor the aircraft arriving to an aerodrome and close to it , say in a distance of the last 5 nautical miles , the future track does not even lead to the runway as part of the future track but it merely points to center of the aerodrome as a whole ! This is simply nonsense to ATC !
3. The main contributors to this program are private hobbyists and the program as a whole was made for their fun. They then made it available to the public via a plug-in software to their systems and the information was passed over to you. They are TOTALY INDIPENDENT FROM ANY ATC UNIT ! Just like radio amateurs you may say. Hence , their coverage is not obligatory and it depends on whether they keep it available or not. If , say , they go on vacation , they are not necessarily leaving the program running at home for weeks so that you get the proper coverage and see the flights you would like in a given area. This is why COVERAGE IS NOT GUARANTEED. Coverage depends on the availability , the position of the receiver , the curvature and relief of the earth as well as the height of the aircraft. Therefore nobody can guarantee a total coverage to all flights ! And as this might produce an uncomfortable feeling to you , let me say that this is true for real ATC as well ! Not all flights are covered by radar everywhere ! Yes ! The reasons are always the 4 previously mentioned.
4. You may check on the program website picture ( as above ) that the information is coming through stations interconnected between the aircraft and the satellites so that the result will end up to your screen. That is actually so …but … nowhere you may see any ATC unit involved . This might disappoint some of those of the ‘general public’ who are even ready to use this program to control traffic all over the world. As an initial idea it only tells that if , and only if , a reliable and real-time information can be sent to one remote unit , then control can be exercised from this unit . This is nothing new. In the very old days , say the aerodrome approach units , where installed into those aerodromes. Now you control them from a remote unit , that is obviously not found in the aerodrome itself. However , the information used is coming from radar systems in and around the aerodrome in question and it is real-time , with system delays of some seconds , which are taken into account and do not fluctuate randomly .
5. The next fallacy refers to ‘precision’. Considering in general GPS to be able , albeit not always and not everywhere , to give positions with a maximum error of some 10-30 meters it is considered that ADS-B is more efficient than deriving aircraft position from radio or inertial navigation which can have errors up to 300-600 meters. The important parameter, however, missed from the previous statement is the time difference between the reception and the displaying of this position. If say it takes some 30 seconds to see a position displayed for say a jet airliner moving at some 500 knots ( 1 knot = 1nm per hour , 1 nm = 1852 meters ) , this introduces an error of about 4 nm ! Modern radar systems have some 6-10 seconds delay on position updates which introduces a normally expected position error of some 1-2 nm. If however a system takes some 1 or 2 minutes to display the same information due to line transmission delays then the error there is of the order of 4 times more or about 4-8 nm ! So it might be that the source of the information is more precise but it arrives with dangerous delay to the ATC to be of any use. So if it is about using the information for serious professional purposes this tool is still unreliable. If you just want to know about what time your friends arrive on a certain flight nobody would mind even a 5 minutes delay – almost a distance of 30-40 nm !!
6. Additionally , the ADS-B equipment used are not all upgraded to provide all its potential to pilots . See AOPA’s experiences and cautions on this link http://www.aopa.org/News-and-Video/All-News/2014/April/02/Portable-ADS-B-seminar
7. Last but certainly not least , is the disclaimer of the producer of the program itself :
Disclaimer. The use of the information presented in Flightradar24 is strictly limited to your personal enthusiast activities (i.e. for entertainment purposes), which specifically exclude any activities that might endanger yourself or the lives of others. Under no circumstances will the developer of this application be held responsible for incidents resulting from the use of the data or it's interpretation.
Please visit the web page www.flightradar24.com to get more info about Flightradar24.com
In simple terms :
Use it for fun or entertainment purposes and
do not interpret the data on your own