Tuesday, May 22, 2007

Day 5: It Ain't Rocket Surgery!

Week two begins...

Today's Lessons:
  • Tower Visibility
  • Airport Conditions, Uses, and Lighting
  • Academy Airport Layout
Today was mostly about Tower Visibility. Tomorrow we have the actual National Weather Service exam for it. This test was one of the Great Mysteries of the courses, simply because no one could really explain it. It requires an 80% to pass, and people have been known to fail it, so quite a few people were worked up over it.

It actually turned out to be pretty straightforward, with a few caveats. What it boils down to is you need calculate the highest visibility for half of the horizon. Let's say to the north you've got 5 miles visibility, 4 miles visibility to the south, and 3 miles to the east and west.

So, let's reason it out:
  • You've got 25% of the horizon at 5 miles, so it doesn't equal half.
  • However, match it up with the 4 miles and that means that at least half of the horizon has 4 miles visibility (25% has 4 and 25% is over 4), so you can claim 4 miles of prevailing visibility.
  • You can forget about the other two sectors which were at 3, since you've already got a prevailing of 4 from the other 50% of horizon.
Bam - prevailing visibility of 4 miles.

It's also got a lot more rules involved. For instance, if 3 of 4 sectors are over VFR minimums, but one is under, then you need to list all of the sectors in the remarks - except for those that match the prevailing visibility. Confused yet? :P

Example: North visibility is 5, East is 7, South is 5, and West is 2. In your METAR weather observation, you would then put:

5SM .... RMK VIS E 7 W 2.

Explanation: West is below 2 miles visibility, so we automatically need to mention the sector visibilities in the remarks. Since North and South equal the prevailing visibility, you can leave them out. However, since East and West differ from the prevailing, you need to include them in your remarks.

We also covered Variable Visibility, which boils down to averaging measurements, and Tower/Surface Visibility. There are rules for them as well, but I won't bore you with the details.

None of it is overly challenging. You just need to pay attention to the rules and apply them.

The lessons afterwards covered the airport layout and airport conditions/usage. The Academy Airport (AAC) is pretty straightforward, with a few bottlenecks and niggles to keep things interesting.

Today's Note: Rocket Surgery! Russ, our lead instructor, was explaining something simple and said "It's not rocket surgery...". I thought it was funny as hell... what's funnier is that I can't remember what the hell he was talking about when he said it. I'll have to use that line somewhere.... :(

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