Critical Point

Also known as... should we return to our point of departure or continue to our destination after an engine failure, if there is no suitable alternate nearby?

Info you need:

• total distance (D)
• reduced (OEI) groundspeed home (RH)
• reduced (OEI) groundspeed out (RO)

For calculating groundspeeds, you need:

• track
• true airspeed
• wind direction and speed

And for calculating the time to the CP, you need

• AEO groundspeed out (GO)

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Formulae:

• Distance to CP = (D x RH) / (RO + RH)
• Time to CP = DCP / GO

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An increase in the tailwind component:

• decreases RH
• increases RO
• moves distance to CP closer to point of departure
• decreases time to CP