ADS-B traffic - receiving dual band vs single band in Los Angeles

[Aviator1213]

ADS-B traffic - experience with dual band vs single band in Los Angeles

Can anyone share experience with using ADS-B receivers (Stratus 1 and/or 2, or Garmin GDL 39) in Los Angeles?

I am especially interested in comparing traffic info received using only 978 MHz (Stratus 1) vs dual band (Stratus 2)...

I had thought that airlines have mostly complied with FAA's mandate to equip ADS-B Out, so having dual-band receivers in Los Angeles basin would basically allow me to see most traffic, seeing as there are always low-flying jets around well within 15-nm radius and +/- 3,500'.

However, I recently saw articles saying airlines have mostly not installed ADS-B Out (exception is FedEx aircrafts), and in fact they are asking for a grace period. This makes me wonder if there is enough traffic info on 1090 MHz to justify the pricier Stratus 2S.

I am a VFR pilot who primarily fly within a 2-hour radius for fun. If there is enough ADS-B Out equipped GA aircrafts, I may opt for Stratus 1s...if no good traffic info is available in LA yet, I may just go with a GPS...as I am unlikely to need in-flight weather for such short flights.

Any experience/suggestions are appreciated!

 

[Unit74]

Buy a used 2. Why shortchange yourself? The 1 won't give you AHRS. GBR feeds into the system as well, so you will see the non ADSB out planes

 

[rbridges]

Buy a used 2. Why shortchange yourself? The 1 won't give you AHRS. GBR feeds into the system as well, so you will see the non ADSB out planes

That's the reason I ponied up for the 2. If I were a vfr only pilot, I would get the 1. Sorry can't really answer the OP question.

 

[John Collins]

Without ADS-B Out installed on your aircraft, you will only see a minority of the traffic that is collision risk to you. As things stand now, about 2/3 of the equipped aircraft use 1090ES. Very few airliners are equipped with compliant systems, but many more are equipped with DO-260A systems that will need to be upgraded by 2020. You can still see those targets, and they will wake up the ground station to generate TISB in their vicinity, but it will all be on 1090 MHz. With a Stratus 1S you won't see these targets or the TISB they generate around them. Except in some areas around airports where GA aircraft frequent, there won't be much activity on UAT 978 MHz. That is not to say you won't receive dozens of targets all the time, it just means the targets which represent a midair threat to you will not show up. Once you install ADS-B Out, the relevant traffic will show up. If you install a UAT ADS-B Out system or plan to, then a 1S will do a good job. If you install a 1090ES ADS-B Out system, I recommend a 2S because a 1S can't receive the ownship data, since it only receives on 978 MHz. Receiving ownship is important, because that is where ForeFlight is able to obtain the pressure altitude being transmitted by the transponder, and therefore to obtain the reference for ownship altitude to compare with the target pressure altitude. The 2S has a pressure altitude sensor, but it is the pressure altitude inside the cabin, which even on a non pressurized aircraft will be generally higher by as much as several hundred feet than the static pressure used by the transponder and ship's altimeter. The 2S pressure altitude will match your ship's altimeter if it is set to 29.92 and the alternate air system that vents to your cabin is used.

2S is better than 1S because of the dual frequency, which does not need the ground station to receive aircraft equipped with ADS-B Out on either frequency. The 2S also has the AHRS and the pressure altitude sensor (cabin altitude). If it were me, I would buy the 2S.

 

[Aviator1213]

Thank you, John!

Is DO-260A one of those systems FAA said they will no longer support starting January 2016?

https://www.faa.gov/nextgen/equipadsb/ins_and_outs/

"However, beginning on January 4, 2016, the following additional criteria must be satisfied in order to be considered a TIS-B/ADS-R "client" by the ADS-B ground stations: Broadcast ADS-B with NACp>4, NACv>0, SDA>0, SIL>0, and NIC>4."​

Very few airliners are equipped with compliant systems, but many more are equipped with DO-260A systems that will need to be upgraded by 2020. You can still see those targets, and they will wake up the ground station to generate TISB in their vicinity, but it will all be on 1090 MHz.

 

[dans2992]

Thank you, John!



Is DO-260A one of those systems FAA said they will no longer support starting January 2016?

https://www.faa.gov/nextgen/equipadsb/ins_and_outs/



"However, beginning on January 4, 2016, the following additional criteria must be satisfied in order to be considered a TIS-B/ADS-R "client" by the ADS-B ground stations: Broadcast ADS-B with NACp>4, NACv>0, SDA>0, SIL>0, and NIC>4."​

I'm guessing most DO-260A equipped planes do not have ADS-B in, so they're not going to care.

 

[John Collins]

Thank you, John!

Is DO-260A one of those systems FAA said they will no longer support starting January 2016?

https://www.faa.gov/nextgen/equipadsb/ins_and_outs/

"However, beginning on January 4, 2016, the following additional criteria must be satisfied in order to be considered a TIS-B/ADS-R "client" by the ADS-B ground stations: Broadcast ADS-B with NACp>4, NACv>0, SDA>0, SIL>0, and NIC>4."​

They should not be affected. Usually these aircraft don't have ADS-B In anyway. The ones that are affected are those that claim to be DO 260B or DO282B but don't comply with the requirements stated in your quote.

 

[Aviator1213]

They should not be affected. Usually these aircraft don't have ADS-B In anyway. The ones that are affected are those that claim to be DO 260B or DO282B but don't comply with the requirements stated in your quote.

Thanks; sounds like Stratus 2S is the way to go since the planes I fly don't have ADS-B out....