Piper CHEROKEE ARCHER II Pilot Operating Handbook page 13

SECTION 1
GENERAL
(b) Meterological Terminology
ISA
OAT
Indicated Pressure
Altitude
Pressure Altitude
Station Pressure
Wind
REPORT: VB· 760
1-6
PIPER AIRCRAFT CORPORATION
PA-28-181, CHEROKEE ARCHER II
International Standard Atmosphere in which:
The air is a dry perfect gas;
The temperature at sea level is 15° Celcius (59 ° Fahrenheit);
The pressure at sea level is 29.92 inches hg. (l0l3 mb);
The temperature gradient from sea level to the altitude at which
the temperature is -56.5°C (-69. 7°F) is -0.00198°C
(·0.003566°F) per foot and zero above that altitude.
Outside Air Temperature is the free air static temperature,
obtained either from inflight temperature indications or ground
meteorological sources, adjusted for instrument error and
compressibility effects.
The number actually read from an altimeter when the barometric
subscale has been set to 29.92 inches of mercury (1013 millibars).
Altitude measured from standard sea-level pressure (29.92 in. Hg)
by a pressure or barometric altimeter. It is the indicated pressure
altitude corrected for position and instrument error. In this
handbook. altimeter instrument errors are assumed to be zero.
Actual atmospheric pressure
at
field elevation.
The wind velocities recorded as variables on the charts of this
handbook are to be understood as the headwind or tailwind
components of the reported winds.
ISSUED: AUGUST 15, 1975