Ryan TCAD 9900 - Section 7: Density Altitude; Engaging Density Altitude

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SECTION VII
DENSITY ALTITUDE
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Density Altitude is useful for calculating powerplant
performance at cruise, and for calculating runway
requirements for high altitude, high temperature departures.
Density Altitude is determined from pressure altitude and
temperature. The Ryan TCAD receives pressure altitude
from the onboard altitude encoder. By manually entering
the outside air temperature (OAT), the TCAD can compute
and display the Density Altitude.
ENGAGING
The Density Altitude function is engaged by simultaneously
pressing the DATA and TRML buttons. The display will
show the previously entered temperature (in degrees F or
degrees C) and the Density Altitude corresponding to that
temperature and aircraft pressure altitude. The Density
Altitude function can be engaged anytime.
Note: Some altitude encoders have a warm-up period of as
much as 10 minutes before the correct altitude is reported.
Be sure that your encoder is supplying the TCAD with
proper pressure altitude.
CAUTION: The TCAD does not operate in the collision
alert function when computing and displaying Density
Altitude.