Flaps @ Airspeed and V/S on approach

Hey guys…

this is a bit of a tricky one.

I was reading on the forum that upon approach you should need about -300 vs per nauticle mile.

Now I know this can differ depending on air port/glide slope but I was approaching a consist terrain airport so no need for a steep guide slope in a 737 (simulator obviously) and I noticed ILS was instructing me to be much higher than 11000ft.

I was 3.5 NM out so (300vs x 3.5 nm = 1050ft)
So why was it instructing me to be higher? What’s the actual ratio of VS to NM desired?

-Also I noticed there’s nothing to suggest what speeds percentiles should be activated.
737s usually land between 130 to 145 knots (GS)
With flaps full (40^)
So what speeds for 30^ etc?

Now I know these are tricky questions so no worries if I’m assumed to be pedantic.

Look forward to your response
CA

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Who came up with the -300 ?
Oh well, as long as your fine on the glide and well prepared there will be no need to stick to that 300 ish number

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300 ft per nautical mile is a good rule of thumb for flying a 3 deg glideslope. As for vertical speed, multiply your ground speed by 5 to get a target VS. (120 KTS X 5 = 600 FPM).
Regarding approach speed, go fly a certain airplane at a given weight and flap setting, slow it down until it stalls, then multiply that by 1.3. That should give you a good landing (v ref) speed number. Add 5 kts to that will give an approximate approach speed (if it stalls at 100, 100x1.3=130 for v ref

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300ft/min sounds very low…

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@Ryan_Vince it’s -300 feet per Nautical Mile (that he is referring to) not per minute. The per minute figure is generally -700 to -800 feet per minute.

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What airport and runway was this?

My passengers must hate me then, I always do min -1000 fpm!

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Google your specific aircrafts POH.

Here is a very useful website for many many aircraft

http://www.skybrary.aero/index.php/Category:Aircraft

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Your airport elevation was probably 50 feet or at that specific airport the glide slope is a little higher then standard. More then likely the first though.

That’s totally irrelevant to the question.

No I found that it is so slow to have VS -300fpm that is why I said that.

He said 300/NM Huge difference 😜

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I’m normally about 3000ft MSL (depending on the region) when approaching the ILS

You must really struggle in Denver 😂

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Haha, I rarely fly in Denver, mainly because there are not many airports and also because it’s a small region, yes I do struggle to land at for example-KEGE

Swap the MSL for AGL and life will get a little easier!

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