Track or Heading?

[DaveReid]

I notice on the screenshots in the Forum that the Flights list has a column headed "Hdg".

Is this the aircraft heading decoded from the Mode S Heading and Speed Report, or is it the track derived from the ADS-B Airborne Velocity transmission ?

MTIA
Dave

[AirNav Support]

Development will know these details but I "think" it uses the track from the ADS-B details and the Mode-S details of heading if the aircraft does not have ADS-B.

Not a question we get often so that will need to be confirmed.

[DaveReid]

Development will know these details but I "think" it uses the track from the ADS-B details and the Mode-S details of heading if the aircraft does not have ADS-B.

Not a question we get often so that will need to be confirmed.

Thanks - if that is confirmed by Development then it would represent an improvement over the "other" Mode S receiver, which only displays track for ADS-B aircraft and neither track nor heading for non-ADS-B.

[AirNav Support]

Unfourtenly its the same as the other Mode S receiver, however as some customers will see sometimes aircraft which don't have a globe icon in the list have heading information, this is usually due to the aircraft either just about to timeout or getting the first ADS-B packets.

[DaveReid]

Unfourtenly its the same as the other Mode S receiver

But they call it track and you call it heading - which is it ?

[Allocator]

Dave, why all the "third degree" questions of late?

I had assumed that you were a RadarBox User and just wanted to get definitive answers, but I can't see why you are so determined to get AirNav to say something then take them to task for their answer?

Maybe just me being too sensitive?

Are you planning to get a RadarBox, or am I mistaken and you've already got one :-)

[AirNav Support]

It is the track, as its from the ADS-B data, we just call it heading as our normal customers will find that more helpful.

Checking our support logs we have one other person mention that and he wanted to use the data for professional reasons.

I am sure Dave is asking these questions under technical curiousty.

[Allocator]

Fair enough.

[sidskeg]

Dave, why all the "third degree" questions of late?

I, for one, am delighted Mr Reid is asking these questions - it can only help in clarifying these areas of doubt, improve our technical understanding and hopefully help RadarBox in becoming an even better product. His wealth of experience with the SBS should be mined for all it's worth.

Sid

[DaveReid]

It is the track, as its from the ADS-B data, we just call it heading as our normal customers will find that more helpful.

Thanks.  I'm not sure I agree with the need to oversimplify things, but I guess that's your prerogative.

It's a shame, though, that neither Mode S receiver can decode the Mode S Heading and Speed Report - IAS would be very useful as that's what we hear ATC using.

[AirNav Support]

We do have IAS in the MyFlights table, however it seems only some AA appear to have IAS details. Don't have a pic of this at the moment, maybe someone can dig one out.

There may be others, rare but some appear with those details.

[DaveReid]

We do have IAS in the MyFlights table, however it seems only some AA appear to have IAS details. Don't have a pic of this at the moment, maybe someone can dig one out.

There may be others, rare but some appear with those details.

Thanks.  I assume you're referring to aircraft that transmit the Airborne Velocity Squitter Subtype 3 (Airspeed and Heading) instead of the much more common Subtype 1 (Velocity Over Ground).

I too would be interested if anyone can dig out a screenshot - looking through my logs it would appear that some (but not all) AFR and UAL B772s fall into this category, as do UAL B763s (although strictly speaking it's TAS rather than IAS that they all transmit). 

Interestingly, those B772s also report magnetic heading in the same transmission, in the absence of track.  SBS ignores this completely and presumably RadarBox does too if it's actually track being shown in your Hdg column.

If anyone is able to post a screenshot which features the above types/operators to help improve my understanding of what aircraft transmit what data, that would be much appreciated.

MTIA
Dave

[tarbat]

Dave, you really should get yourself a Radarbox, if only for research purposes!!!

I'll keep a lookout for anything showing an IAS.  A couple of UAL B772's on the network at the moment.  Interestingly, they don't show IAS, but neither do they show GS or Heading.

[DaveReid]

I'll keep a lookout for anything showing an IAS.  A couple of UAL B772's on the network at the moment.  Interestingly, they don't show IAS, but neither do they show GS or Heading.

I've been running a packet capture for the last couple of hours and it's logged 20 aircraft transmitting airspeed, mostly B772s of UAL/COA/AFR/MSR, plus a solitary E-3, a B763 and a DLH A321.  All the 777s transmit magnetic heading too but not, rather unsportingly, the AWACS :-)

RadarBox's ability, as per Support's post, to display this data would be a good justification for buying one, but a screenshot would be a nice confirmation.

Any offers?

MTIA
Dave

[AirNav Support]

Someone in the US should get plenty of them, I have feeling the IAS values are not sent across the network which leads them to showing blank on the network (something we hope to rectify in later versions)