Forest Airpark 1: The IFR Approach
You are on an instrument flight plan heading to the Forest
Airpark 1 Cache. The weather is below the minimums allowed for
flight under Visual Flight Rules (VFR), so you will have to shoot
the GPS-Bravo instrument approach into the airpark. As with most
instrument approaches, this approach starts at the Initial Approach
Fix (IAF) and continues on to an intermediate fix, followed by the
Final Approach Fix (FAF) and then hopefully the destination if you
have it in sight. Make sure you bring enough fuel to make it to the
destination, shoot the missed approach and make it to an alternate
with the required reserves defined in the regulations.
Air Traffic Control (ATC) has put you into a holding pattern at
the IAF while you setup for the approach. You can calibrate your
altimeter to the HIO barometer on 127.65MHz or 503-640-2984. You
may want a flight computer for this one.
FORST (IAF)
While in the holding pattern at 1100 feet, you notice a sign on
a tree with a number that is formatted XX.YY.ZZZ. Once you identify
this number, you are cleared for the approach, and may descend to
1030 feet towards EVGRN.
EVGRN Lat Mins = FORST Lat Mins – ((ZZZ – 60) /
10000)
EVGRN Long Mins = FORST Long Mins – ((XX2 +
YY2 – 41) / 1000)
EVGRN Checksum, using N45 AA.BBB, W122 CC.DDD -> AA + BBB +
CC + DDD = 1385
EVGRN
As you approach EVGRN, you will see another sign with two
five-letter words. Take each word individually, and find the sum of
the numerical equivalent of each letter. A=1, B=2, Z=26, etc.
Crossing EVGRN your new altitude will be 830 feet.
MARKR Lat Mins = EVGRN Lat Mins + ((2nd Word Sum * 2 + 13) /
500)
MARKR Long Mins = EVGRN Long Mins – ((1st Word Sum * 9 +
30) / 1000)
MARKR Checksum, using N45 AA.BBB, W122 CC.DDD -> AA + BBB +
CC + DDD = 1234
MARKR (FAF)
Once you have reached the FAF it is important to announce your
position to the local traffic based on a reference marker located
below with the two numbers that identify it. Once you verify you
are still on course, you can continue the descent to the decision
height (DH) of 530 feet.
AIRPARK Lat Mins = MARKR Lat Mins + ((Single Digit Num * 65 + 2)
/ 1000)
AIRPARK Long Mins = MARKR Long Mins – ((Four Digit Num -
308) / 10000)
AIRPARK checksum, using N45 AA.BBB, W122 CC.DDD -> AA + BBB +
CC + DDD = 1203
FOREST AIRPARK 1
As with all instrument approaches, you are required to have the
minimum visibility defined by the approach before you can continue
the approach to a landing. In this case, that is the amount of
error in your GPS reading. If the visibility is not met or you
don’t find the cache, you will have to shoot a missed
approach by initiating a left climbing turn direct FORST and hold
as published at 1100 feet.
NOTE: You can make it to within 5 feet of the
cache on trails. As you approach the cache (less than 150 feet) and
become perpendicular to it on the trail, please do not trump
through the vegetation by taking a direct shot to it. Instead,
continue past it a little further on the trail until it turns
sharply to the right. At that point go to the left about ten feet
and then you should notice an old trail that heads back up the hill
the cache is on. There should be very little bush whacking for this
one. Since the original cache was muggled, I placed the new,
smaller one, further up the hill. The coordinates may be off by 50
or so, but the hints will make it an easy find. Please cover it
back up well.
------------------------------------------
The initial contents included many flying toys, a small
airplane, and expired aeronautical charts (great for flight sims).
It also started off with a Travel Bug whose mission is to make to
Oshkosh, WI for Airventure, the largest airshow in the world.
"Instrument flying is when your mind gets a grip on the fact
that there is vision beyond sight." - U.S. Navy "Approach" magazine
circa W.W.II.
