Lesson #15: Saturday, May 25th, 2019

I was at the airport on-time for my 10am reservation, but the aircraft was not. We had to wait until 10:15 before the previous student and instructor came back in.

We asked about fuel, and they said it was nearly full when they took it out. But when we got into the aircraft and turned on the master switch, the fuel gauges showed down near a quarter tank. As my instructor is fond of saying, you don't trust what people tell you about fuel, and you don't trust the fuel gauges, either--you need to get up on the wing and check it yourself.

There are two tanks, one in each wing. You climb up on the strut on each side of the aircraft, remove the fuel cap, stick a tube down into the tank all the way, put your finger on the top of the tube and pull it back out. When the tank is full, you'll see fuel up to the '8' mark. The first tank I checked was only up to 2.75, so Steve called for the fuel truck.

The hourly rental rate includes fuel, so all it takes to get fuel is a phone call, and the guy comes out and fills it up. 73924 can take about 25 gallons on each side and uses about 12 gallons per hour.

Once we called for fuel we proceeded with the rest of the preflight check. The 172 has tricycle gear: one front gear and two main gear. Part of the pre-flight is to check the condition of the tires. The left main gear had a serious bald spot: not only was the tread gone, but it had worn through most of the layer under that. Steve's guess was that someone had used the brakes too aggressively and "flat-spotted" the tire. If you see metal showing through the rubber, the aircraft is not safe to fly. There was no metal showing today, but Steve said it was very close to it.

We checked the oil and discovered it was low. Steve went over near the fence to some containers I'd never noticed before and came back with a quart of oil which he poured into the engine.

Once we were done with the preflight we needed to get moving. We had the plane reserved until noon, but despite getting the plane late and having to put fuel in, we didn't want to return it late.

I taxied down to the run-up area and did the run-up checks, which involves running the engine up to 1800 RPM and checking the gauges. One of the final checks is "Primer in and locked". (The primer lets you squirt a little extra fuel in the engine; you'd use it when the engine is cold. Leaving the primer unlocked messes with the fuel/air mixture and causes the engine to run rough.) I could see it was in, but I hadn't needed to prime the engine, and I hadn't tried to pull it out to ensure that it was locked. Steve must have noticed that the engine was sounding a little rough, because he prompted me to pull on the primer--and it was not locked.

Instead of pattern work Steve decided we'd do some coordination work up north of PDK. My takeoffs are not great, but I'm doing ok at reliably getting the aircraft rolling down the runway and into the air. Once up we headed out on a course of 330, just a little to the west of north. We usually head NE to the South end of Lake Lanier, but today we ended up over CNI, the Cherokee County field near Canton.

The aircraft felt a little sluggish climbing out. I think I was climbing a little too fast. The best rate of climb in the 172--also known as the Vy speed--is 73 kts. I think I was closer to 79. It also didn't help that it was a hot day. Heat makes air less dense which means less lift. PDK is at 998' above sea level, but the "density altitude" that morning was close to 2,900', meaning the airplane is not going to climb as fast as would on a cooler day.

We made it up to around 4,000' where there were some puffy white cumulus clouds. Steve suggested we go up above the clouds because the air would be smoother up there. VFR rules say you must keep your distance from clouds: more than 500' below, 1000' above, and 2000' away horizontally. It felt like we might have been closer than 2,000' at some points, but there's no easy way to tell that up in the air.

We did some coordinated turns left and right, and some steep (45') 360 degree turns. When the wing is banked to 45', it develops less lift, so you have to pull back on the yoke to keep the plane from descending. It's very easy to keep your eyes in on the gauges as you're doing this, but Steve reminded me that you want to keep your eyes outside the aircraft and use the horizon to tell if you're properly banked and if you're losing or gaining altitude.

The only thing I didn't do today was handle the approach and landing. As we were downwind in the pattern, Peachtree Tower called and asked if we could "make short approach". Basically, they wanted to get us on the ground quickly so we could stay out of the way of other arriving traffic. Given that I'm still learning how to handle a normal approach, I asked Steve if he would take it. It's actually kind of fun: abeam the numbers on a left pattern, Steve cut the power to idle, put in full flaps, and started making a continuous left banking turn, holding 70 kts, and got us on the ground inside of perhaps a minute or so. It's the same procedure you'd use if you'd lost power. Steve has tried to have me practice this maneuver before, but usually we have other traffic ahead of us and we have to fly a normal pattern. It's something I'll have to learn.

It was a good flight. I felt much more like a PIC (pilot in command) than a student. At one point I thought we were going to be too close to a cloud if we made a 360 turn to the right, so I first made a left turn to get us heading away from the cloud. On the way back to PDK, we needed to lose altitude, but with the clouds, we needed to go down a little faster than the usual 500' per minute, so I went ahead and did it.

Flying up near clouds is amazing. It's one thing to pass through them in a big jet; it's another thing entirely to be picking your way amongst them. Much of learning to fly is intense concentration during which you don't really get to appreciate the fact that you're in the air; today I got to experience a little of the sheer joy of flying.