Well I think it’s been a couple of weeks since I posted last. One of the reasons for this is that I’m now alternating between flying lessons and ground school classes. Since I’ve already done the FAA examination by taking night school ground class with Twin Cities Aviation, it’s just revision for me and so I’m not going to update you on these classes. I’ve actually already covered what I studied in those classes in several previous posts. I will mainly be updating only my flight lessons and anything new I learn in my pre and post flight briefings.
Friday 13th, 2012 was yet another very hot day following several hot days we’ve been having this summer here in Minnesota. Many of these have unfortunately been humid days. We do have humid days but not so many in a row, far too many for my liking. The situation is made worse when you’re seated in the cockpit of a small airplane for over an hour. Anyway, today’s class was from 1:00pm – 3:00pm, peak time for the heat. As I shut my car door and was walking toward the school, I saw my instructor walking just ahead of me. “Hello Logan” I said. He greeted me and we shook hands. I went to the front desk and checked in and Logan said, “Come on back, when you’re done pre-flighting”, “Okay” I replied. After pre-flighting I went to Logan’s office where he asked me if I had reviewed the maneuvers we were going to cover today. “Yes I have” I replied and so Logan proceeded to ask me questions about stalls and steep turns. Once I had answered them satisfactorily Logan asked if I was ready to fly. I replied yes and then asked, “Should we first call the Flight Service Station (FSS) and get the Standard VFR weather report?” Logan thought for a moment and then said, “Yes call them”. I called the FSS in the manner I mentioned in my last post. But before making the call I confirmed with Logan what the minimum information I should get was. “So at a minimum I should get, the Altimeter reading, the Wind direction and Speed and…..?” “Temperature” replied Logan. I got the following information from the FSS:
- Altimeter – 29.95
- Temperature – 29 C
- Dew Point – 20 C
- Wind – 190 @ 10 K
- No TFRs – i.e. No temporary flight restrictions
- No adverse conditions
- Cold front approaching (this was much later than my flight time)
- Clouds at 3,200 ft
I was given a lot more information than I’ve shown above. Once I received this information I proceeded to calculate the Pressure Altitude using the Altimeter reading:
(29.92 – 29.95) x 1000 = (-0.03) x 1000 = -30.00ft. Regardless of the Altimeter we’re given, we always subtract the figure from the standard atmospheric pressure of 29.92 inches of mercury. This is why sometimes we will get negative figures as we have in this case.
Next the result is added to the airport (or local field) elevation. Crystal field elevation is 869 ft. Therefore: 869ft + (-30.00) = 839 ft. This last figure of 839 ft means that it will feel like we’re lower than we actually are due to the pressure. Logan then said that we should get slightly better performance of the plane because we’re closer to the sea at this height, and since there are more molecules nearer the sea, the airplane will perform better. He then continued to say that I should note that we haven’t, for now, taken the temperature in to consideration. When we do, the figures will be different and will give more meaning. We would be able to evaluate (predict) the performance of the plane much more accurately.
Having calculated Pressure Altitude, my instructor asked me if I had my Pilot’s Operating Handbook (POH) with me. I said I did not as I had forgotten it. But if I had it, I knew why he wanted to me to refer to it. Pressure Altitude and Temperature affect the way a plane performs and the POH contains various graphs from which you can calculate/extrapolate/interpolate different figures about say engine performance, climb performance, glide performance etc. with respect to the temperature we obtained from the FSS and the pressure altitude I had calculated.
Then we both went out to the plane and I immediately felt the heat as I climbed into the cockpit. After having gone through the checklist, I called Crystal ground and we were directed to runway 14R and this is what I had anticipated since the winds were from an angle of 180 degrees and runway 14R was the closest to the wind direction. After the before takeoff check list was complete, we were ready to take off and just as I was about to call Crystal tower for a request for takeoff, Logan said “Let’s just stay in the pattern today because it’s already 2:10 pm” and my lesson was to end at 3:00pm. So this is what we decided to do. It was a blustery day and a good day to learn some cross-wind landings. I’m not going to describe every detail here but only the gist of what I learnt in my lesson.
The main thing when flying the pattern or when entering the pattern is that one must know which runway you’ve been given to land, and the wind speed and direction. Then you use these to fly the plane to land smoothly. When you know the direction the wind is coming from you’re then able to compensate for that wind so you can fly the plane correctly in the pattern by using the ailerons and rudder correctly. Knowing the runway you can make the correct approach. We were taking off from and landing on to runway 14R which meant that we were flying into 14R i.e. flying in to the wind which was coming from an angle of 180 degrees at 10 knots. You always, when possible, land into the wind. We completed 6 landings today and by the last landing I was gradually getting to understand how to crab in to the wind and use opposite rudder to keep the plane flying straight toward the runway. Further I also learnt that you may have to constantly adjust the crab angle and the rudder to keep the plane straight as wind direction and wind speed may change.
My next ground school class and flight lesson will be with another instructor as Logan will be unavailable until Friday of next weeek.