TIS-B inconsistent


#1

TIS-B data reports on Skyview seem to be inconsistent.

Sometimes I receive them, sometimes I don’t. Appears to be random.


#2

That is normal. The TIS-B data is intended for reception by specific aircraft. It is transmitted directionally and only where needed.


#3

Understand. However, oftentimes I will have up to 8 or more TIS-B hits and then, poof, all disappear. None displayed for a period of time, (several minutes to an hour or more) and then, magically, they return.

Targets can be ops vehicles, tractors mowing, fire apparatus, aircraft, etc.

I think I’ve even received TIS-B outputs from train locomotives.

I guess what you’re saying is that it takes a specifically equipped aircraft to initiate the TIS-B reports. Until that happens all other TIS-B transponders remain silent.


#4

Yup. TIS-B requires a specific aircraft for the broadcast to happen.

First, TIS-B is sent from the ground station and not the planes. It is in the direction of the specific aircraft.
Second, the aircraft has to report that it is only has UAT so they are missing the ADS-B position.

There might be other conditions for the ground station to send out TIS-B but it doesn’t happen frequently. I think the interval is every 30seconds or so before it stop the TIS-B broadcast after it was turned on.

TIS-B will include lots of other types of vehicles. The rebroadcast will usually include local ground vehicles and ADS-B planes. I don’t know why trains would be in the feed though.

Skyview will mark the color of the row differently for TIS-B vs UAT. It should be fairly easy to tell the difference between an UAT transponder vs the rebroadcast.