Strange ADSB behavior

[diablouser]

I suspect that this is normal behavior, but is very strange.

I was flying with another aircraft, about 1/4 mile behind him at the same altitude in a 500 FPM decent.  On the map screen he was showing as yellow traffic with a O altitude difference about in the right place.  Just like it was.

On the PDF, he was showing right in front at O difference, but he was not standing still.  The aircraft was standing still and went zipping past right thru my nose.  Then he would immediately appear back in front and go zipping past.  I moved a little to the right and he went into my left wing. 

Kept happening until I lost the ADSB signal due to terrain. Felt like the system was throwing rocks at me! 

Bruce Patton 

 

[dynonsupport]

That would seem to be what the ground network was sending you as traffic for your aircraft.

I suspect that this is normal behavior, but is very strange.

I was flying with another aircraft, about 1/4 mile behind him at the same altitude in a 500 FPM decent.  On the map screen he was showing as yellow traffic with a O altitude difference about in the right place.  Just like it was.

On the PDF, he was showing right in front at O difference, but he was not standing still.  The aircraft was standing still and went zipping past right thru my nose.  Then he would immediately appear back in front and go zipping past.  I moved a little to the right and he went into my left wing. 

Kept happening until I lost the ADSB signal due to terrain.  Felt like the system was throwing rocks at me! 

Bruce Patton 

 

[dynonsupport]

I assume the other plane wasn't ADS-B out?

In that case, the system only knows where the other plane is about once every 6 to 12 seconds as it's swept by radar. So it draws it in that place, and then in the next few seconds you fly by it, and then it gets swept again.

An ADS-B out plane transmits once a second, so it's faster, but this still happens on a different time scale.

 

[diablouser]

Right, the other plane was not ADSB equipped. 

The map display maintained the or correct distance the entire time.  How come I didn't catch it?

The  map display must consider the speed and direction of the other aircraft or else you would see this all the time.  Does the PDF ignore them?

I sure wouldn't want to fly formation with a large group!

Bruce

 

[swatson999]

I sure wouldn't want to fly formation with a large group!

Bruce

Which is why everyone's transponders are off, except for one, when flying formation...

 

[thibault]

That's why in the USAF, the call from lead was "XYZ Flight, Choke the Chicken."  Response was, 2...3...4

Translation for the "great unwashed", is "stop squawk".

 

[GalinHdz]

That's why in the USAF, the call from lead was "XYZ Flight, Choke the Chicken."  Response was, 2...3...4

WOW, I hadn't heard that in a LONG time. Later they changes the term to "Strangle Parrot".