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Given the following information, what is the heading M and GS?

Required course: 045°M
Variation: 15°E
W/V: 190°T/30 kt
CAS: 120 kt at FL 55 in standard atmosphere

• A
055° M and 147 kt
• B
056° M and 137 kt
• C
036° M and 151 kt
• D
052° M and 154 kt

Refer to figure.
Determine OAT temperature at FL80:
ISA temperature at FL55 = 15 - 2 x 5.5 = 4ºC

Using the navigation computer, convert 120 kt CAS to TAS:

1) Align the pressure altitude of 5 500 ft window with the OAT of 4ºC;
2) Once the wheel is aligned, find the CAS of 120 kt on the inner most scale. Read the corresponding TAS of approx. 130 kt on the outer scale.

Convert magnetic track into True:

Use the mnemonic:

• Variation West, Magnetic Best.
• Variation East, Magnetic Least.
 True track (T) Variation (V) Magnetic track (M) 060º 15º E 045º

Determining Heading and G/S with the flight computer:

(1) Place the centre of the rotating disk on the value representing the true airspeed (130 kt).
(2) Place wind direction (190º) under the true index.
(3) Mark wind velocity (30 kt) upwards from centre.

NOTE:

When the question provides a track => mark wind velocity upwards from centre.
When the heading is known => mark wind velocity downwards from centre.

(4) Place your true track (060º) under the true index.
(5) Slide wind Velocity mark to True Air Speed (130 kt);

• Ground Speed reads under centre => 147 kt;
WCA reads between centre line and wind velocity mark => 10ºR.

Using Wind Correction Angle (WCA) and Track, determine Heading:
Wind Correction Angle (WCA) is the angular value opposite to the drift angle, and it refers to the heading angle correction in order to keep your aircraft in the desired track:
• Therefore, True Heading = TT + 10ºR = 060º + 10ºR = 070º(T)