Are there any rules of thumb for quickly calculating or estimating the required vertical speed / rate of descent in feet per minute which corresponds to a given glideslope for a given groundspeed?

My own rule of thumb is this - for a standard 3 deg glideslope 100 kts of speed will mean almost exactly 500 fpm. So since these values are proportional it would mean that 20% higher speed will require 20% higher VS. So I know what it is for 100 kts and make adjustments from this number. There is probably a better rule.Michael J.WinXP-Home SP2,AMD64 3500+,Abit AV8,Radeon X800Pro,36GB Raptor,1GB PC3200,Audigy 2http://www.precisionmanuals.com/images/forum/747400.jpghttp://www.hifisim.com/images/asv_beta_member.jpg

Hi,I've always multiplied my groundspeed by 5.Same results as previous post, but perhaps a little easier than percentages to work out.My flight instructor told me this one and he's never crashed on final using it! (Well, not that he's admitted to)Stuart.

The last page of all TPPs (aka plate books) is a Descent Table with appraoch angle/feet per nm on the left and ground speeds on the top with feet per minute in the table.It may be scanned on the net somewhere.----------------------------------------------------------------John MorganReal World: KGEG, UND Aerospace Spokane Satillite, Private ASEL 141.2 hrs, 314 landings, 46 inst. apprs.Virtual: MSFS 2004"There is a feeling about an airport that no other piece of ground can have. No matter what the name of the country on whose land it lies, an airport is a place you can see and touch that leads to a reality that can only be thought and felt." - The Bridge Across Forever: A Love Story by Richard Bach

UK approach chasrts also give a table from 180kt to 80kt.

Divide your airspeed by 2 and add a zero. So, if you are going 100kts, you would have a 500fpm descent rate, 80 kts would be a 400fpm descent rate, provided that you are currently correctly on the glideslope.

Thanks for the replies guys, much appreciated. I will use the multiply by 5 rule of thumb as a rough guide and look for descent tables where available.

I bet I can divide my airspeed by 2 and add a zero before you can find your ground speed and multiply it by 5. Scott

Depends on the glideslope. The glideslope on an ILS can be from 2.7

Donny AKA ShalomarFly 2 ROCKS!!!Hey Scott, even simpler than what I've been doin'! I drop the last digit of my GS from the GPS, divide by half and add two zeros!!!There is one advantage to using airspeed on the glideslope: If you have a signifigant tailwind you will start to get higher even though you mantain your target descent rate. So you might get an additional clue that maybe you should use a different runway, or be on the lookout for shear if the ATIS is saying a wind direction close to blowing down the runway. Using GS takes away that hint.Best Regards, Donny