What’s the closest unintentional distance you’ve been to another aircraft mid air? Also, were you near an airport or airway? Two weeks ago, I was approaching the pattern at KEAU. We heard on radio that traffic was inbound from our direction. I glanced out the pilot window just in time to see him pass a few hundred below us. It was enough to get my attention.
I had a guy who overtook me from behind on short final and passed underneath me, all this after him seeing me in front. I know this because I talked to him on the ground after the incident. His claim was that he didn’t think I was in the pattern because I was higher on final than he usually sees other planes. I was flying my Champ at the time and I fly higher approaches than some of the other pilots who fly low drag it in approaches. In a Champ you can easily lose altitude and airspeed anytime with a slip. That’s one thing that plane does very well.
All you can do is shake your head and walk away at someone as dense as that.
Closest was the day of my first solo, while flying in the pattern with my instructor. I was on downwind and was watching the runway to judge my distance when my instructor suddenly took the controls and rolled us what was probably 60 degrees but felt like more, he then rolled us level just in time to see a 172 going the opposite direction, right where we had been. That guy was not talking on the radio, just transiting right through the traffic pattern at 1000 AGL. Given my attention was on the airport and flying the pattern, I would have never seen him…
Years ago I had a Bonanza go the other way about 200 feet off to the side and maybe 200 feet below me. It was close enough to see he was holding up an unfolded sectional chart. Probably never saw me.
The other one was at Bermuda Dunes. I departed in a Westwind and passed a cherokee toodling up the freeway at about 1000 AGL. He was not on the unicom frequency but was talking to PSP approach. We were at the same alitude when I went by him and about 300 feet away.
edit: almost forgot. Right after we got our TCAS ROME ATC cleared an opposite direction flight for his decent. We were down at FL 280, he was slow starting his decent and Rome didn’t catch it until he was through about 900’ feet above us but still 2 miles away. The controller caught it and had the 737 climb back up but by the time all that was said he was down to 600’ straight overhead. I was about 2 seconds from disconnecting the autopilot and heading down. We all decided that was too close.
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- NW bound out of San Jose Muni with the old man on board. Abeam Lockheed and Moffett I put the right wing down with opposite rudder so he could get a good view of the building he worked in. A Mooney inbound called the tower announcing himself 5 seconds after he passed 50’ below me on a reciprocal heading.
I learned to love TCA’s. 
The really scary thing is until you get something like this… (cumulus-soaring.com/zaon.htm) or a TCAS …you don’t realize how many you didn’t see. I remember my first trip in a plane that had one of the Zaon’s on the dash, the sky seemed awfully small that day.
I was a student pilot on a solo flight to the practice area in a C150…I was getting ready to practice steep turns, and suddenly I saw a wheel go across my windshield…It was the other C150 that belonged to the flight school owned the airplane I was I in. I was 17 at the time, and thought I was going to be in trouble when I got back. Turns out the other airplane’s student or instructor never saw me or knew I was there.
1964 - as a USAF student in a T37 I was doing aerobatics with an instructor. I was preparing to do an over-the-top maneuver and started a dive to pick up airspeed. Of course, I had my head in the cockpit, staring at the airspeed indicator, when my instructor basically screamed and slammed the stick to the right! I looked up just in time to see another T37 coming head on! It banked right at the last second as well and we darn near rubbed bellies! What was interesting is that I just sat there, dumb-founded!
Over the next 50 years I had a few other close calls but that one stands out! Needless to say, keeping my head on a swivel scanning for traffic became an in-grained habit after that. The other couple of near-misses where usually weather-related when I was young and foolish…and met another young and foolish pilot out running scud too.
Two lessons: LOOK AROUND! And don’t scud-run! 