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Guest iain williams

LANDING SPEED TERMINOLOGY 737 SERIES

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Guest iain williams

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To my understanting the extra 5 knots you add are there exactly because of any headwind component you might have. Therefore it doesn't matter where the wind is blowing from, if there is wind present add 5 knots to the vref. If you perform an approach @ Vref without those extra 5 knots you will find yourself consistently going below vref and performing very firm landings. When there are gusts reported the story changes. You should add half of the gust factor to Vref + 5. That is also done to protect your approach. So for example if you are landing and the metar says 35009G17KT that means that you will add 5 to the Vref and then another 4 knots. Why another 4 knots? that is because 4 is 1/2 the gust factor (17-09=8 --> 8/2=4) All in all your approach speed would be Vref + 9. I hope this was clear and right as well. Someone else might be able to correct anything I said that might've been wrong. But I thing this is how it's done. Best Regards,Victor Limahttp://www.precisionmanuals.com/images/forum/800driver.jpg


Cheers,
Victor M. Lima
 

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If the steady wind is 10 knots or less add 5 knots to Vref. Example: If Vref30 = 126 then 126 + 5(1/2 the steady wind) = 131 Target Vref. Set Final approach MCP Speed to 131 knots.If the steady wind is greater than 10 knots add 1/2 the wind up to a maximum of 20 knots to vref.Example: If Vref30 = 130 and steady wind is reported at 14 knots then 130 + 7(1/2 the steady wind) = 137 Target Vref. Set final approach MCP speed to 137 knots.If there are wind gust reported, add 1/2 the steady wind plus all of the gust factor.Example: If Vref30 = 128 and steady wind is reported to be 13 knots gusting to 23 knots then Vref 128 + 7(1/2 the steady wind) + 10(allof the gust) = 145 Target Vref. Set the final approach MCP Speed to 145 knots.In any headwind conditoins, Vref + 20 maximum.Any tailwind conditions, Vref + 5 maximum.If a landing with the autothottle engaged to touchdown such as a Autoland then it's a Vref + 5 maximum. This is because the AFDS and autothrottle can sense and compensate for wind and gust changes.Floyd


John Floyd

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Guest iain williams

Floyd and VC - many thanks for your replies and help in clearing up this problem. Best to you..........Iain

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