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Old February 16th 05, 03:16 PM
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Now this I find interesting.

I understand obstacle clearance, but had no idea that runway markings
and taxiway spacing affects DA.

I can understand runway markings (although I thought they were
standard for precision approaches) but taxiway spacing?

Porque?




On Wed, 16 Feb 2005 05:06:50 -0800, wrote:



Dave S wrote:

An important part of the precision approach environment is the airport
surface itself: an adequate runway clear zone and adequate approach
lighting. Just because you can get a WAAS signal does not mean a
particular runway is going to be appropriate for a 200 ft minimum.


For whatever it's worth, the runway markings, taxiway spacing, and obstacle
clearance areas are what make for a 200-foot Decision Altitude (DA).
Approach lights (ALS) are for visibility credit. With everything else
satisfied but no ALS the DA will still be 200 feet, with a visibility of
3/4. Add ALS to that environment and it becomes 200 and 1/2.