Free Fright & ADSB

[Low Fidelity]

Hi all

I was doing some background research for a possible thesis in free flight conflict resolution and stumbled across ADSB. Bizarrley enough it then popped up in a documentary on National Geographic so I guess it must be quite important.

My problem is, I have very little idea about what it is or does?!
I kinda understand it as an active replacement for radar but that's where I end. Is this thing only working in Alaska?

Any input would be hugely welcome. Actually whilst your here, any comments about the free flight theory? Suggestions or criticism.

Ta :ok:

Low F

[BigHitDH]

I also know very little about ADSB, but here is what I do know, or have head about it.

ADSB is basically a much upgraded TCAS system, using a satellite as an intermediary for radar transmissions.

The ADSB box on board aquires the aircraft's location, velocity and altitude via GPS, and the "reports" this position to the satellite at regualr intervals. During this time it also aquires the position, velocity and altitude of all other ADSB equipped aircraft within a selected radius (max of 200nm) and displays all the aircraft on a screen with a terrain overlay pulled from a terrain databse from a GPS "moving map" system.. ADSB can also show any possible conflicts in much the same way as TCAS.

ADSB has an advantage over TCAS in that it does not require "line of sight" communication between conflicting traffic. Good in Alaska with all the high mountains and low flight levels of all the GA traffic.

ADSB also exhibits the same functions as a GPWS system, using the tearrain databse to predict ground height, as opposed to a radio altimiter. It also has tall structures in the database, such as buildings and antennas.

That's pretty much all I know about it, I hope that helps,

Regards,

[revelry]

OK - a subject reasonably close to my heart. I'm working on the standards for world-wide implementation currently.

ADS-B, standing for Automatic Dependent Surveillance - Broadcast is actually a datalink to send information about your a/c to other a/c around you... indeed, this information is broadcast to anyone who has the ability to listen in.

Satellites are not necessary - if you're in line-of-sight, then that will do fine. If you're not, it could be re-broadcast by a ground station (or in rare cases, satellites). Generally, its not necessary, since why would you want to know about a/c more than 100NM away when you're in flight?

The concept that uses this datalink (ADS-B) is called ASAS - Airborne Separation Assistance System... it consists of the datalink, on-board computers, and some kind of flight deck display.

IT IS NOT RELATED TO TCAS! Indeed, strenuous efforts are being made to ensure that the two systems are kept separate (TCAS is a safety net, ASAS is not). ASAS, in general (and certainly in the medium term) will not solve conflicts for you either. It will enable you to space or separate yourself with respect to traffic around you... whether that is from one aircraft (spacing/separation) or all aircraft (free-flight) depends on time-scales.

The terrain overlay is a completely separate feature. ADS-B has nothing to do with terrain - it is purely about the mobile targets (aircraft, ground vehicles etc). So although the terrain database may predict ground height, and show it on the same display as ADS-B targets (e.g. in a GA aircraft), the two concepts are not related.

The Alaska work you mention (called CAPSTONE project) is not the only one... Australia are just about to implement ADS-B in their airspace, and live trials have been on-going in Europe for some time (Sweden, the Mediterranean, France etc) - mostly co-ordinated by Eurocontrol and the European Commission.

I'll stop there before I write essays - low fidelity - I've emailed you.

Rgds,

Rev.

[BigHitDH]

Rev-

Thanks for the clearup!

[Fright Level]

Free Fright .. thought you were referring to my landings :D

[VectorLine]

or a competition prize from China Airlines

[Low Fidelity]

Guys, your input is hugely welcome, ta for all the hard work!

I'm trying to follow up some work done last year and evaluate what information is vital to resolving a conflict issue, and thus what is vital to display in a conflict resolution tool. Starting to feel very naive though. Think I might have bitten off a bit too much!

I'll keep ya posted

Thanks Again

Low Fi

p.s. the title was inspired by my mates reaction when he first heard about the whole free flight concept!