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Guest Puttmeister

Visual runway landing...help!!!

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Guest Puttmeister

Hey I could use some help with a problem I have and I hope you can help me.When flying an IFR route in FS9, often with the PMDG 747-400, I get told by ATC that i should expect a visual approach. I then follow the ATC intstructions to decsend or turn.I.e. I

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Hi Patrick:The rule is more or less: given that you have obtained your approach speed (Vref)from your FMC, multiply that speed by 5I will try to explain it. A good cruise descent profile is descending 1000 feet in 3 Nmiles (the 1/3 rule).Normal glideslopes have a 3 degree gradient, that is a bit different: more or less descending 1000 ft in 3.3 miles Well, imagine your approach speed is 150 kts. That is 150 miles in one hour, or the same: 3.3 miles in 1.32 minutesSo, in a perfect glideslope you will fly 3.3 miles in 1.32 minutes and you will descent 1000 ft in the same time, then in one minute you will descent:1000 / 1.32 = 757.57 ft/min757.57 = aprox 150 x 5For a normal range of approach speeds you will get:130 kts........650 ft/min140 kts........700 ft/min150 kts........750 ft/min160 kts........800 ft/minYou can see that dscending 700/750 ft/min is a good vertical speed for the final approach phase.I hope it can help you. Regards Jose Luis


signed: José Luis

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I select the runway as the approach on the APPROACH menu and as a rule of thumb use 300 ft/nm as the descent rate (it's actually closer to 280 ft/nm for 3-deg); therefore, I want to be 1000 AGL at about 3 nm from runway. I don't use the autopilot, just A/T with speed set for the approach, fly the airplane in landing configuration below 1000 AGL. Use the VASI if available.


Dan Downs KCRP

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