straight line to the curved line. Go the left in a straight line and read the collection per degree Fahrenheit.

b. Multiply this value by the difference between instrument temperature and 75° F. to obtain the total correction

noting whether it is a plus or minus correction.

c. If the instrument temperature is above 750 F., add the correction algebraically to the altimeter reading.

d. If the instrument temperature is below 750 F., subtract the correction algebraically from the altimeter reading.

e. For example, the altimeter reads 3,000 meters, the thermometer reads 50° F.

(1) Find 3000 M on chart.

(2) Follow up to correction curve.

(3) Go left to edge and read correction per degree F In this case the correction is plus .09 M per degree F.

(4) Since the temperature of 500 is 250 less than 750 F., subtract (plus .09 x 25) from 3000 M; or 3000-

(+.09 x 25) =3000-2.25 = 2997.8 M, which is the corrected reading.

Figure 15. Typical individual instrument temperature

correction chart.