If a pilot is using an iPad for traffic sequencing, how important is it for him to know that the aircraft calling downwind is in fact the same airplane he sees on the iPad in that location? There could be a non-ADS-B aircraft on downwind too - and maybe knowing that two airplanes are on downwind and the ADS-B aircraft is not making callouts would maybe cause him to look out the window?
It is a new ball game - I will think about it.
I understand why another pilot in the pattern wanted to know your N number. If I hear an aircraft approaching the pattern and see an aircraft in that same area on my ADS-B "in" display, it's helpful to know if there is one aircraft in that area, or two and/or if the one I am seeing visually is the one I am seeing on the ADS-B "in".
I took 23 years off from aviation and a lot of things changed. However, on the plus side that rapid immersion into the new environment has made it easier to adapt.
There are pros and cons.
I have a Statux and a 9.7" i-Pad with Flight Plan Go that I use for the charts, the moving map display, inflight weather and traffic, with a big caution and caveat on that last one.
On the "pro" side:
1) Having inflight weather and in particular the radar mosaic makes like much easier when navigating around afternoon thunderstorms as you can pretty well see what is behind the CB currently in front of you and you then better plan a round around CBs without getting dead ended. I'd have loved to have had that 30 years ago.
2) Also like the electronic charts in terms of more frequent updating, the ability to resize the image, and the ease of flight planning capability and the ease of adjusting the course enroute if you need to divert around weather.
3) ADS-B "In" traffic is also a plus. If an aircraft has ADS-B "out" it'll show up well beyond normal visual range, and I can tell pretty much exactly where to look for that particular aircraft and I can usually see them sooner, especially if it's one of the idiots with an over all dark paint scheme that serves as very effective camouflage.
There have been a few cases where I have not seen aircraft at all, other than an ADS-B indication. For example I flew into Wilson a couple weeks ago and despite ADS-B, the PA-28 calling his position on base and final, and knowing exactly where he was/should be, I didn't see the solid dark gray aircraft until it crossed the threshold of the concrete runway. He was only about 1.5 miles away at that point.
On the "con" side:
1) ADS-B traffic poses an increasingly significant threat as pilots are becoming increasingly dependent on it to spot traffic for them. As noted above it is a big aid in helping pilots spot aircraft farther way. On the other hand that only works if the other aircraft has ADS-B out. Pilots still need to scan for other aircraft, and I'll argue we need to scan *more* than before due to the higher probability the other pilot isn't looking outside at all.
Looking back over the last 6 months, I've had or seen 4 close encounters.
I had a close encounter at KRBW when an executive jet reported being 3 miles SW of the field we'd just departed. I didn't see him in that quadrant and on a hunch lifted a wing tip to see him curving toward us with zero relative motion about a half mile to starboard (west of the field). He obviously didn't see us and was obviously head down in the cockpit doing something else - probably looking for ADS-B traffic on a display. I did not have ADS-B "in" at the time, and it would almost certainly have alerted me to the fact he wasn't where he reported himself to be, and that we were on a potential collision course.
I also had a near miss (200' vertical separation, 0' horizontal separation) with a hangar mate who had departed from our home field without transmitting anything, while we were approaching the field about 8 miles east and flying into the setting sun. The only warning I received was a bit red circle on the ADS-B in from a skin paint on a ATC radar. I don't know how that works, but I have noted that if a non ADS-B equipped aircraft is on a potential collision course with me and we are both being painted by an ATC radar, in some circumstances the other aircraft does show up on mu display giving me at least a few seconds warning. However, at long range, radar isn't all that accurate, and it only updates every 10 to 12 seconds so the data is imprecise and slow to show a conflict. That kind of warning will ALWAYS be very limited.
In this case he was at fault for being radio silent. He also knew I was out flying as we share bays in the same row of hangars. I wasn't without sin either however as I was approaching the field into the sun and more or less on the extended center line of runway 7. It's not the smartest way to approach an uncontrolled airport.
I also had one of the helicopters from the regional hospital cross about 1000' in front of me east to west at the same altitude (1000' AGL) just after I called 7 miles south of a county airport. I saw him coming in at my 2:00 and kept him in sight as we closed. It's possible he also saw me as well and saw that while we were close we also had sufficient relative motion. But I wouldn't bet my life on it. He was no doubt ADS-B equipped but was not showing on the ADS-B in display. It was either off, or not functional, or the ADS-B traffic system wasn't up to speed.
The last was at this same small county airport where a C-172 on descent overtook me with maybe 100' vertical separation, after I'd broken into a right turn to spot him as it was obvious from his report he was behind me. From the angles involved I doubt he saw me. He continued on course going well below pattern altitude and cutting off an aircraft on final who made a hard right turn out of the pattern. That pilot requested a radio check to ensure he was transmitting and I advised I could hear him just fine.
In short, visually scanning for traffic is more important than ever, especially here in eastern NC. We have a combination of a lot of uncontrolled airports, both registered and unregistered, as well as a lot of MOAs and restricted areas that serve to concentrate traffic, and a large concentration of non ADS-B aircraft, with at least a couple flown by real idiots.
2) ADS-B is based on GPS information and requires *accurate* GPS information to work. Here in eastern NC we've had periods where the Navy and or Marines have been running exercises involving GPS interference with resulting widespread areas where GPS isn't accurate. NOTAMs are issued and GPS approaches are closed, but I suspect most pilots don't realize the GPS / ADS-B traffic they have become reliant on is now also less accurate.
3) Pilots should still be using ATC traffic separation services and should regard ADS-B as backup. The same goes for ATC, but based on what I'm seeing and hearing that doesn't always seem to be the case.