Guess what I just found.
10.62.
I looked up how they calculate rarity and it’s I think a good system, but not what I expected.
My first thought, and what they originally did, was that rarity was simply an index of how many of that aircraft type exist.
Instead, it’s really a ranking how many hours a given type flew in the look back window. So that’s my some of the kit planes I’ve caught have higher rarity than the B-29. More of some of these high rarity kit planes exist, but they almost never fly. So in reality, they’re much harder to grab.
Instead of just looking at how many aircraft exist, we now base rarity on actual flight activity. The values in Season 1 are based on measurements from a 204 day period.
Here’s how it works:
For each aircraft model, we add up the total flight time of all its individual aircraft during the period.
We then normalize this total by dividing it by the length of the measurement window.
The result is what we call “Full-Time Equivalent Aircraft” (FTEA). An FTEA value of 1 means that, across the fleet, the aircraft type flew the equivalent of one aircraft operating non-stop for the entire period.
To turn this into a rarity score, we apply the formula:
Rarity = 7.5 – log(FTEA)
Examples
Boeing 737-800:
Across all aircraft of this type, the total flight time in the 204-day period was 292,568.95 days.
That equals 1,434.16 full-time equivalent aircraft.
Applying the formula gives:
7.5 – log(1434.16) = 0.23Cessna T303 Crusader:
Across all Crusaders, the total flight time was 185.55 days.
That equals 0.91 full-time equivalent aircraft.
Applying the formula gives:
7.5 – log(0.91) = 7.59
I had a colleague years ago who told me he collected airplane tail numbers. I was rendered temporarily speechless at this, but then asked him what he did with them. He said that he talks to other collectors and they trade them. More silence followed. The OP’s version sounds more complex.
I woke up super early this morning and actually used an entire 2-hour unlimited photos upgrade for the first time. Two hours is a long time to stare at your phone catching planes, but by the time I earned my 150 coins back I still had an hour and fifteen minutes left… I ended up 250 coins ahead, and got my first orange cyber card! Overall, I would say the 2-hour upgrade is worth it, but I couldn’t possibly stand to do it more than once a month or so.
We on the Dope have our own weird little collection going:
2-1/2 years, 3300 posts about custom license plate spotting. What are we thinking? 
And it’s not even the first thread on this topic. But definitely the one with the most staying power.
Interestingly, the ancient threads died quickly. The last-decade’s threads lasted awhile before petering out. This one will probably live for the rest of the board’s lifetime. Is the difference that custom plates are more common now or that we’ve turned into boring geezers with little else to occupy our minds or days?
I have to relearn how to use the SDMB… I think I’ve been replying to people’s posts, rather than just adding a comment to the thread. I’ve been gone a while.
There are two reply buttons. One at the lower right of each post. Clicking that creates a reply directly to that post(er), with a backlink in your post’s upper right connecting to their post.
The other reply button is farther down the page below the last post at the right of a row of similar buttons. That one replies to the thread.
Discourse sorta muddies matters when you post-reply to the post that’s directly above yours (IOW post-reply to the current last post in the thread).
In that case, Discourse internally knows the posts are connected, but your post’s display makes it look like you replied to the thread, not the immediately preceding post. Example: this post was created as a direct reply to your post, but there’s no backlink at my upper right. And yes, this particular Discourse quirk annoys many of our people.
So you may not be as confused as you think.
I got an ultra today, a Maule M-6 Super Rocket. Although I’m not sure what the pilot is doing out, since we’re in the middle of a severe thunderstorms associated with the remnants of tropical storm Cristina.
I guess that guy likes to live dangerously.
I’ve gotten a few really interesting aircraft over the last few days by switching airports, but I think it’s much cooler when I can grab something exotic locally. This morning I got a flight of three Hawker Hunters, and just now I got a flight of two Dassault Mirage F1s.
What bums me out though about the game is it seems to me that the feed is delayed. At least when I compare it to my ADS-B receiver. I missed a chance to see those Mirages because it showed them overhead in the game when they were really a few miles down the coast from me already.
Edit: another Hawker Hunter just passed directly overhead - got a good look this time.
I went to a park near Logan Airport today. There did seem to be a lag of a few seconds between the real plane and where it was shown in SkyCards. Still pretty damn impressive that we can get that info on almost real time.
From what I could tell, the pictures shown in SkyCards do match the specific aircraft ot represents. The paint jobs on JetBlue aircraft matched.
As far as I’ve been able to ascertain, if a tail number has a photo, it is indeed a photo of that specific aircraft. There are some really cool pictures out there, too!
There’s a balloon 55,000 feet over Indiana.
Chinese? 
Because all the data in the game comes from the Flightradar24 site, it can grab actual photos from their library. Planespotters devote a lot of time to uploading massive libraries to of aircraft photos.
Must be some kind of exercise going on over the Pacific west of Monterey. I got the Hawker Hunters and the Mirage F1s again as they passed over on their way up the coast.
Tons of Blackhawks too.
That’s an Aerostar high-altitude stratospheric research and monitoring balloon. Looks like it’s over Dayton now.
If it makes it to Boston I’ll grab it.
I don’t know whther to thank or curse @BomTek for getting me hooked on this.
Had a rather productive field trip to Charles de Gaulle Airport - picked up a Beluga (8.10), Falcon 6X (8.82), Centre Est DR-220 (9.79), and a Aerospatiale Magister (11.22). Also unlocked quite a few European, African, and Middle Eastern airports, which will come in handy later. Not bad for 30 mins work using a free relocation ticket.
Thus far a Lark Commander is my most rare by a fair margin: 13.51 with a Hatz biplane in second place with 11.03.
I am fortunate-for the purposes of this game-to be in north metro Atlanta, where we have Atlanta Hartsfield, Peachtree-Dekalb (lots of private jets), and Dobbins air base nearby.
I would have definitely snagged the Beluga if I’d seen it. I have CDG free for the rest of the week, so there’s always a chance.
I never played Pokemon Go, but this game is reminding me of some of the things I heard about it. Are they similar?