Thursday, October 20, 2011

Oral PTS Prep

This morning it was too foggy to fly, which was actually good. This morning my CFI and I were going to do "oral prep work". Which simply means he walks me through the questions I can expect on the oral portion of the PTS checkride and makes sure I know the answers.

I found out a couple things.
  • I know my aerodynamics and airplane systems much better than I expected
  • I second guess myself a bit too much, my first answer is usually right
  • No matter if I second guess or not, if I verbally walk through the concepts behind each answer, I get to the right answer
Here's an example of the last item:

Low to High, Clear the Sky

You are in straight and level flight at 3000 MSL and pressure is 29.92, you fly into an area with pressure at 30.08, what will happen?

I got stuck on what the altimeter would read, which is if you remained physically at the same altitude, the altimeter would read lower than you are actually at. This is true. But what you would actually do in the plane is you would climb, as the altimeter reads lower and lower, you would start adjusting your altitude to ensure the altimeter reads 3000 MSL if you didn't re-adjust the altimeter for the new pressure. When I through it through carefully, it made sense. I've heard the "High to low, look out below" thing.. but I didn't quite "get it". But when my CFI explained what you would logically do in the plane as a result of the pressure change, THEN I got it. He also told me something I'd never heard before. "Low to high, clear the sky." If you are flying from an area of lower pressure to higher pressure in "straight and level flight", you will climb... clear the sky.

Pitot-Static Fun

Of course we covered the pitot-static system very carefully. I did well on that. I have a good understanding of the concepts behind it, and, once again, as long as I walked through the scenario I came out with the right answers.

Apparently this was the week of the pitot tube for my CFI. He told me a couple interesting stories about blocked pitot tubes. One where he flew a plane earlier this week, and then two days later he found some interesting mud on the pitot tube opening. So he looked inside the tube and pulled out a dozen or more insect larva!

The fun part was when he was doing his standard drawing of the pitot-static system and then drew a bird with its beak over the pitot tube opening to suggest a bird flew into the pitot tube. What happens in this case he asks? I answer. Then he explains why he was halfway laughing when he asked. He said a couple years ago he was doing his standard drawing and asked the question of another PPL student. The student answered, "That depends. Is the bird sucking or blowing?" That's a very good question :)

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