Visiting the Formans in Tallahassee
It was November 30, 1990. I had a reason to visit Tallahassee. I rented good old N739SK, a sturdy C-172N, from the CAP Flying Club and flew up fairly early, hoping to have lunch with Willis Forman’s daughter Jeannie, a long-time friend.
I flew up to “Forman Field” and made a couple of passes trying to land, but I couldn’t get low and slow enough. I was a bit afraid of the trees. I know now I could have gotten in and out but I was still a pretty new pilot then.
So I flew over to Quincy and Willis came over to pick me up.
We flew a couple of times around the pattern from the grass strip just to confirm the performance of the plane but still, I felt better where I was. Willis drove me down to his house where we began to wait for Jeannie to show up. She never did. She must have had a change of heart. She invited me up to see her and “changed her mind.” No comment.
It was getting dark and some winter weather was moving in so I asked Willis to drive me back to Quincy. It was dark when I took off, on an instrument flight plan direct to Cross City, then Ocala, then Orlando. (CTY-OCF-ORL)
I climbed up to 5000′ and I was in the clouds. I was watching my instruments closely when I noticed that the VSI was stuck in a 200 fpm climb although my altitude wasn’t changing. This was disconcerting.
I finally realized that my static port had become blocked with the light mist I was flying through. It was well above freezing so I know it wasn’t ice (about 10 deg C). I switched to the alternate static port. Only a slight change and still no change in VSI.
I was thinking about smashing the glass on the VSI but I knew the club mechanic Lenny would be very upset with me unless it was a last resort.
“Hey Jax Center this is 9SK can you tell me my altitude?”
“Well your Mode C is indicating 5,100 ft.”
“No I don’t trust the mode C, I think I have water in my static system. Do you have any radar that can actually SEE my altitude?”
“No we’ve never had that. Only some military bases have that and nothing near you. I’d advise against changing altitude too, because the ceiling is reported to be 1500′ in your area and there are a couple of towers in your flight path, not to mention that radiosonde balloon near Cross City. Your current heading should keep you clear of that though.”
“OK well let me think about this.” I said.
Air Temperature Corresponds to Altitude.
You are all thinking, why didn’t I just look at my Foreflight and see my GPS altitude? Well this was last millennia and we didn’t have that. I had a LORAN on the plane, that’s it!
But I did have an outside air temperature gauge. I was at 10 deg C right now. I decided to just keep it there as best I could. I had been taught that altitude adjusts OAT by 2 deg C per thousand feet.
“So Jax, is there anyone else out here that I could have a conflict with?”
“No sir, you are the only one under 15,000 feet along your route of flight for at least 50 miles.”
I informed him of my decision to gauge my altitude by looking at my OAT. “That’s pretty clever. I’ll direct you with vectors if you get near anything, horizontally.” I listened to the sound of my engine and watched the RPMs closely because of course the Airspeed Indicator had also become unreliable. By doing that I was able to keep the temp at 10 deg C for another 50 miles.
Interesting Next 50 Miles
And about 50 miles later JAX informed me that I had cleared the Cross City radiosonde so I could go direct OCF (Ocala) VOR. That was a relief. About 20 DME from Ocala I broke out of the clouds. It was completely clear the rest of the way. And of course, the static system immediately cleared up and I was indicating altitude, airspeed and vertical speed once again. Guess what, I was at 5,100 feet! I was only 100 feet off. I told Jax I had my static system back and resumed the rest of the flight without event.
So the OAT Gauge is a Poor Man’s Altimeter?
Well yes. I proved that.
Thinking back, I was pretty crazy to go single engine IFR at night in a C172. It’s amazing how my judgment has changed over the years. I would never do that now.