FlightAware Discussions

Wrong feeder positions: A problem for data integrity?

Hi folks

When I take a look on the FlightAware ADS-B Coverage map, I see a few other feeders near my feeder location. It seems, some of those feeders are not correctly placed on the coverage map, because the feeder descriptions point to places (e.g. airport names), which are up to 50 km away. I assume, those feeder owners have set the position data (Lat/Lon) or the “Nearest Airport” wrong. Therefore, I have 3 questions:

  1. Shows FlightAware ADS-B Coverage map the correct positions of the feeders? (I know, there is an option to obscure the position up to 10km)

  2. What will happen with the data integrity if several feeder owners have set the position or the “Nearest Airport” wrong? I assume the quality of MLAT will decrease in that areas and other double- and security-checks routine could fail.

  3. Is there a possibility to inform those feeder owners, to correct the feeder position data or “Nearest airport” name? As a normal user, unfortunately we can’t inform those feeder owners directly.

Are there anybody who can answer my questions?

Nearest Airport name is chosen by the user. I don’t think it has any relevance to MLAT.

Note that you can choose how accurately your feeder appears on maps. This allows for feeder privacy as you stated above.

MLAT requires the set location to be within a certain accuracy(about 300ft/100M, I think) and this detail is only available to Flightaware and the feeder owner. The use of MLAT has decreased significantly in countries that have rolled out ADS-B mandates. It has not totally gone away as it is possible, at least in the US, to fly huge distances without the use of an ADS-B transponder.

Agree. The “nearest airport” seems to be largely a matter of preference. I’m not sure what purpose it actually serves.

I could also see where a lot of people could inadvertently get it wrong. For example, I have my nearest airport set as KVUO, which is Pearson Field, in Vancouver WA.It is almost exactly 1 mile closer to me than KPDX, which is the much larger Portland International Airport. I would imagine that most people in my area would automatically pick PDX, just because it is the more obvious choice.

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During setup the device is getting a “nearest airport” assigned based on location. I assume many of them are changing it, but not all.

I have set up my two feeders recently. After the setup both had different airports assigned. That is a but, because both feeders are within a range of 10 meters and the “wrong” airport is behind the nearest one.

II assume the chosen nearest airport name hasn’t a big impact on MLAT.

But what will happen if the feeder owner has set the positions (Lang/Lot) wrong?

I’m agree, with ADS-B the position of a feeder isn’t so critical anymore. But there are already concepts to protects ADS-B data against spoofing attacks or fake position data. The MLAT mechanism is big help to double-check the ADS-B data against attacks. Therefore, the right positions of the feeders are still important, that this mechanism works properly.

Clock synchronization never happens and the receiver does not participate in mlat.

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