Transponders

[Frank Giger]

I think we're typing past each other, which is most likely my fault.

I don't really have a dog in the ADS-B hunt, but I can think of a couple reasons for discrete codes.

First, it can assist by giving out type of aircraft and normal speeds. You know what makes me concerned? Both the airports I frequent occasionally get business jets, and they don't fly the pattern. They sometimes talk jibberish, giving their position by instrument check points (and some sound a bit miffed when I ask them to state their position to the airfield). I'm coming around base to final at 50 mph and they're screaming in at 150. I have a tiny plane, and they might not physically see me or understand that I'm gonna take some time to land and turn off at the first taxiway....and I get a business jet up my rear or landing on top of me.

Second, and most likely, is institutional inertia. Transponders have unique codes, so therefore ADS-B does, too. No thinking required, because it's Transponder Plus, and so it flows naturally.

[Mike M]

What makes you think a discrete code is necessary for traffic avoidance systems to work?

Nothing. Any more than I think a traffic avoidance system like ADSB would have prevented the over 13000 midair collisions in the USA that were reported in the latest data I could find, 2013.

[Marc Zeitlin]

Nothing. Any more than I think a traffic avoidance system like ADSB would have prevented the over 13000 midair collisions in the USA that were reported in the latest data I could find, 2013.

Don't want to jump into the middle of whatever this discussion is about, but I have to ask - given that the 24th Nall report for 2012 indicates that there were a total of 6 mid-air collisions for GA aircraft that year (3 fatal and 3 non-fatal), and that even if we assume that level of mid-air collisions every year that airplanes have been flying, it would take 2,167 years to have 13,000 mid-air collisions. This seems somewhat unlikely, given when aircraft started flying and when more than two of them might have been in the air at the same time at the same place.

So unless you're including bird strikes as mid-air collisions, and unless you're counting some indeterminate # of years worth of them, I'd be interested to know where that 13,000 # came from...

Curious minds want to know.

[Mike M]

So unless you're including bird strikes as mid-air collisions, and unless you're counting some indeterminate # of years worth of them, I'd be interested to know where that 13,000 # came from...

Curious minds want to know.

I couldn't re-find the ref for the 13,000+ number, so I'll drop back to the number I was able to find this time. Over 11,000. My apologies for not saving the original ref.

Of course that includes bird strikes. They're midair collisions with the proven capacity to render the aircraft unairworthy. Not to imply that an AIRCRAFT traffic avoidance system isn't a noteworthy accomplishment. Just to remind that ADSB will do nothing to avoid the most prevalent collisions, nor to ameliorate the growing risk of collision with sUAV air vehicles which are not participating in ADSB technology.

FAA Wildlife Strike Report. Figure 1, the graph on page 66. 2013 bar.

[cub builder]

It's not "funny." Just because you chose not to avail yourself of ADS-B in doesn't mean that others flying in the same airspace are as cavalier with their safety.

OK. It's not funny. But it is a fact. Your statement about "it works without the absolute reliance on ground based systems" is incorrect. It is possible, if only we all lived in the FAA's ideal world. But that isn't reality.

I don't know why you would think I "choose" not to avail myself of that ADS-B data or am "cavalier" with my safety. In fact, I use a dual channel transceiver in the plane I use in busy airspaces and am highly critical of the vendors that are selling single channel receivers as the end all solution. That would be why I mentioned the issue with single channel receivers. Before buying an ADS-B unit or locking yourself into a vendor, one has to read very carefully to see what is not included.

-Cub Builder

[Helipilot]

Frank's post about 1-3,000 AGL makes me wonder about the MSL altitudes being used for ADS-B. If I take off at Gunnison, CO I'm already at 8,000+ MSL and I too usually poke around under 3K AGL. Therefore I am at 11k MSL, what are your opinions Guys?