Protection from obstacles in terminal area

S

Skyhawk890

Filing Flight Plan
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Nov 29, 2015
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Rumford, ME
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Tony
Can anyone recall how much protection (in feet) is provided from obstacles on an instrument approach within the terminal area, specifically let's say inside the IAF (between the IAF and the runway threshold)?
 
I seem to recall 300' on nonprecision approaches. Forget the obstacle protection on a precision approach but someone will be along shortly.
 
1,000(2,000 for mountainous) for en-route/terminal segments, 1,000 for initial segments, 500 for intermediate segments, 250-350 for final segments.
 
Last edited:
Gucci Pilot said:
1,000(2,000 for mountainous) for en-route/terminal segments, 1,000 for initial segments, 500 for intermediate segments, 250-250 for final segments.
Click to expand...

So to be clear, if you look at the RNAV (GPS) RWY 32 approach for KIZG, the tower located between the IAF SERPA and ANDRU is 567 feet below the authorized altitude of 3100, which is appropriate given the 500-foot minimum for intermediate segment?

I actually flew this approach today in VMC and was very surprised how close I was to this tower and I was "on the numbers" the whole time. I seriously question the accuracy of the charted height of this particular tower.

Knowing what it looks like during a calm VMC day, I would hate to fly this in the soup with moderate turbulence and/or wind sheer!!
 
Skyhawk890 said:
So to be clear, if you look at the RNAV (GPS) RWY 32 approach for KIZG, the tower located between the IAF SERPA and ANDRU is 567 feet below the authorized altitude of 3100, which is appropriate given the 500-foot minimum for intermediate segment?
Click to expand...

Looks that way...
 
Skyhawk890 said:
Can anyone recall how much protection (in feet) is provided from obstacles on an instrument approach within the terminal area, specifically let's say inside the IAF (between the IAF and the runway threshold)?
Click to expand...

NPA:

Initial Segment: not less than 1,000 feet.
Intermediate segment: not less than 500 feet.
Final segment: Usually 250 feet, but NDB with FAF is 300 feet as is on-airport VOR without FAF. On airport NDB without FAF is 350 feet. DME ARC final segment is 500 feet. (only a couple of those.)
Circle to land is 300 feet except for on airport NDB without FAF, in which case it is 350 feet.

Varying accuracy codes are applied to all man made obstacles, dependent upon accuracy of survey. 20 feet is added to topographical data contours.

Assumed adverse obstacle (AAO) is added to terrain, depending upon distance from airport.

Additives are made for vegetation, and are location specific.

Approaches with vertical guidance: final segment obstacle clearance is very complex and contains many variables. The obstacle clearance becomes less progressing from the FAF to the DA-point. On a standard ILS or LPV ("200 and 1/2") the obstacle clearance is approximately 130 feet at the DA-point. But, that would usually not be on centerline.
 
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