PPL Ex 18 (vii): NAVIGATION: The Navigation Log, HDG(M), GS

On the WIND SIDE of the computer: (Please see Blog: “The Dead Reckoning Computer” or “Wizz Wheel”). From TAS and the WIND VELOCITY applied to TRK˚T we can calculate TRUE HEADING (HDG˚T). The HEADWIND or TAILWIND COMPONENT for each ‘leg’ is also graphically displayed on the plotting surface of the computer. Therefore the GROUNDSPEED (GS) is easily calculated by adding or subtracting the component to/from the TAS.
Applying VARIATION to TRUE HEADING will give us MAGNETIC HEADING (HDG˚M) and applying DEVIATION to MAGNETIC HEADING will give us COMPASS HEADING. (Note 1: VARIATION EAST, MAGNETIC LEAST. DEVIATION EAST, COMPASS LEAST. Note 2: ISOGONALS are lines of equal variation and are printed as pecked lines on the Aeronautical Chart. Note 3: A COMPASS CARD is displayed in the aircraft which gives a COMPASS HEADING to steer based on a MAGNETIC HEADING.)

From - To - TAS - TRK(T) - W/V - HDG(T) - VAR - HDG(M):
Shipdam Alconbury 97.5 - 250 - 280/25 - 257 - 3˚W - 260
Alconbury MeltonM 97.5 - 315 - 280/25 - 307 - 3˚W - 310
MeltonM Shepshed 97.5 - 280 - 280/25 - 280 - 3˚W - 283

From - To - GS - Dist - Time - Fuel Rqd - ETA:
Shipdam Alconbury 76 - 44.5 - 35.2 - 2.94 - +35
Alconbury MeltonM 75 - 33.0 - 26.4 - 2.20 - +51
MeltonM Shepshed 72 - 14.0 - 11.7 - 0.98 - +63


Please read Blog: August "Navigation Ex 18 - Legend”