FlightAware Discussions

Position only not picking up flights or just part of flights

I just installed a new transponder Sandia 165R and UAvionix in/out EchoUAT with Fyx-exp out/in Transciver bundle. Did the FAA ADS-B test and all working fine. However, when I go in and try to look at the flights after or live with Flight Aware sometimes they are not there and/or only a small part of the flight is listed. I did a flight following the other day and it tracked it precisely when I was squawked specific code and in contact with flight control. I make sure and fly in known coverage areas and nothing. What is happening any ideas? N288SL

FlightAware’s receiver network has limited UAT coverage in your area.

Screenshot from 2020-11-11 10-26-58

(go to https://flightaware.com/adsb/coverage#data-coverage, set altitude to 0-10kft and turn off all the checkboxes except for UAT)

Check and make sure your altitude data is working correctly. This flight “10-31-2020 14:47:59 to 10-31-2020 15:56:19” and this one “11-05-2020 17:19:49 to 11-05-2020 17:43:15” were two that I checked at the FAA site and it flagged the “Baro Alt” and “Mode 3A” checks.

Try this link https://adsbperformance.faa.gov/PAPRUsersGuide.pdf

It is the user guide for the reports.


On this flight 11-10-2020 18:04:15 to 11-10-2020 18:35:14 it had your “Baro Alt” but the “Mode 3A” check failed.

How can I increase the UAT coverage in my area?

Very helpful. I see we have MLAT coverage what is that and can I use it.

Encourage people to add more UAT receivers. See if you can get one installed at each of the local airports. Even if they only have limited range at airports, they would still be helpful for tracking purposes.

UAT considerably less range because aircraft that use UAT typically fly much lower therefore have a smaller ground footprint. There needs to be many more of them to cover the same area as 1090Mhz ADS-B.

Doing research I have found that a FlightFeeder increases coverage. Will it increase coverage for UAT?

If I install FlightFeeders will that help the UAT coverage?

Yes, we have FlightFeeders that are set up for UAT.

If you have access to on- or near-airport locations where you could deploy a FlightFeeder then I’d encourage you to apply for a FlightFeeder. (Mention that you’re looking for UAT coverage when applying)

Alternatively if you’d like to DIY it, then you can build a PiAware receiver that can receive UAT and feed that data to FlightAware (typical cost $100-$150).

Both will show the received data on a locally hosted webpage and also feed the data to FlightAware to improve our overall coverage.

MLAT (multilateration) uses multiple 1090MHz receivers to find positions for Mode S transponders that are not ADS-B capable. In your case if I read the specs right I think you only have Mode C, not Mode S, so it wouldn’t help in your case unfortunately.

OK so if I apply for a Flight Feeder with UAT coverage there is no cost, except to install it on my end, is this correct? Yes PiAware costs but not sure what advantage this has? What is the range of UAT coverage with the FlightFeeder? Hoping for 25 miles so I can install in many local airports (CXP, TVL, TRK, MEV, SPZ,) and cover this area.

This is my UAT piaware in NYC

I am only about 50ft AMSL and have a lot of terrain shielding. Most of my position reports are <40NM.
A location with more height would have more range.

Look at www.heywhatsthat.com to get an idea of the possible range based on aircraft altitude. Remember that UAT aircraft tend to fly much lower and their transponders don’t need to pump out 600W. Helos at 1000ft are not going to have much range until the area is very flat. The aircraft range would be similar to the range of the VHF radio on the aircraft to the ground(or how well can you hear the ATIS from an aircraft). I know the power is only 10-16W for most GA aircraft and a transponder may be a lot more. I am just using it as a guide.

Even from my low location, I get ADS-B 1090Mhz aircraft out to 200NM. Before Covid-19, I could regularly see the Qantas 747s coming into JFK at 185NM(They happen to come in on the right direction for me to see them far out).
If you know any EMS or Amateur radio towers in your area, you may want to contact them to see if you can add a receiver to them. The close transmitters may require better filters (ie cavity filters) to reduce the overload from the transmitters.

Yes I have been working on this also. My last 3A error was only 3% so improvement verseses 100% error. My other aircraft with exact same system passed both Baro Alt and Mode 3A N31PH.