Section IV: Appendix



Above Ground Level. Height above ground level, rather than height above sea level (which is what the altimeter measures).

Decision Height (DH)

The point on an ILS instrument approach where the pilot must have the minimum ceiling and visibility mandated by the instrument approach plate to continue the approach to a landing. At that point, if the runway environment is not in sight, further descent is not authorized, and a missed approach must be made.


Fixed Base Operator. A facility on an airport where pilots may purchase fuel, have maintenance done, etc.


Initial Approach Fix. The point in space where an approach to a landing officially begins. This term, borrowed from the vocabulary of instrument flight, is used here to mark the point where an approach to an off-airport landing begins. (See window).

ILS minimums

The minimum visibility a pilot must have at Decision Height (DH) to continue an ILS instrument approach to landing. Usually 200 feet vertically, and one-half mile horizontally.


A heavy, knee-high boot often made of canvas with a rubber or leather sole. It uses felt inner-liners about a half-inch thick that can be removed for drying. These boots, originally designed by the Eskimos, are the best available for seriously cold temperatures, and are comfortable below -50 degrees F/-46 degrees C.


Remain Over Night.


Standard Instrument Departure.


Visual Flight Rules. The minimum ceiling and visibility a pilot must have to fly under visual conditions. These limits usually are 1,000 feet vertically, and three miles horizontally; when the ceiling and visibility get below that, a pilot is expected to fly using instruments (often ignored by bush pilots flying specially-equipped STOL aircraft in remote wilderness areas).


The imaginary point -- or points -- in space along an approach path where a pilot needs to make various configuration changes to his aircraft -- airspeed, flaps, trim, prop, landing gear (if appropriate), and altitude -- prior to landing. (See the section in Chapter 17 called The Raven for a description of an off-airport approach to a landing using the "windows" concept).

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