While in flight, Pressure Altitude can be read right off the aircraft altimeter IF 29.92"
is dialed into the Kollsman Window AND there is NO instrument error.
Given an IAS, it will be necessary to calculate the CAS because it is a more accurate value
to use when calculating the TAS. Looking at the instrument calibration card (Figure 4.4-5),
an IAS of 255 knots equates to a TAS of 252 knots. Since there is not a 255 (IAS)
available on the calibration card it is necessary to use the closest value of 253 (IAS). At
253 knots (IAS) the correction factor is 3 knots to arrive at a CAS of 250 knots. Therefore,
the same correction factor, -3 knots, would be applied to an IAS of 255 to arrive at a CAS
of 252. This would be an example of correcting for instrument error.
Once CAS is calculated, the TAS can be solved for using the CR3 navigation computer.
Figure 4.4-5 Airspeed Calibration Card