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I found these Climb Gradient to Rate tables online to use for instrument departures that convert FT per Min to FT per NM.  Great to download and to put in your ForeFlight docs folder. Remember if you can’t meet climb gradient then you can try  a VCOA (Visual Climb 0ver Airport) procedure if available.

https://irp-cdn.multiscreensite.com/fb79e6f7/files/uploaded/Gradient To Rate Table.pdf

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There a similar table in the front of the Government approach books. In Foreflight, it's in Documents in the FAA drive: Digital Terminal Procedures Supplemental, last page.

Here's a trick I use: Define the "Speed Factor" (SF) as nautical miles per minute. So a groundspeed of 60 kts is a SF =1; 90 kts is SF =1.5; 120 kts is SF =2, etc.

The required ROC (ft/min) is the gradient in ft/nm x SF. So climbing at 120 Kts with a required gradient of 350 ft/nm requires a ROC = 2 x 350 = 700 fpm.

The Speed Factor is also useful for planning descents. The altitude you need to lose (in thousands) multiplied by the Speed Factor gives the distance to top of descent at 1000 fpm. If you want to descend at a more leisurely 500 fpm, just double the distance. Say you need to descend 9000' at 500 fpm and 180 kts. 9 x 2 x 3 = 54 nm.

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Like this one from the FAA Terminal Procedures Publication? It's been in the paper volume forever (or at least the past 30 years).

I'm curious. What have you been using until now? I agree with PT20J about the ease of calculation but I prefer the tables. 

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Edited by midlifeflyer
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Like PT20J I just do the arithmetic in my head.  Feet per mile times miles per minute = feet per minute.  

Example — The Aspen Seven departure requires 650’ per nmi to 13,000.   At 120 knots (ground speed, BTW) that’s 2 nmi/min.  650 x 2 = 1300 feet per minute minimum to 13,000.   


Few Mooneys can meet that requirement.  

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This is a common skill that is tested in the instrument written.  The table shown is more than adequate.  For a 3 degree glideslope which includes most, but very close to 2.75, simply take the ground speed during descent and divide it by two and multiply by 10.  For instance 90MPH divided by two is 45, times ten is 450 FPM.  Very easy to do in your head.

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On 6/10/2021 at 4:03 PM, MBDiagMan said:

This is a common skill that is tested in the instrument written.  The table shown is more than adequate.  For a 3 degree glideslope which includes most, but very close to 2.75, simply take the ground speed during descent and divide it by two and multiply by 10.  For instance 90MPH divided by two is 45, times ten is 450 FPM.  Very easy to do in your head.

You shouldn’t be descending in your climb gradient. :)

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On 6/10/2021 at 6:10 PM, eman1200 said:

ft/nm * gs /60 is pretty easy to do on the calculator on your phone.  you DO have a phone with a calculator, don't u?

You don’t need a calculator doing it my way.  Do it in your head very easily.  100/2 is 50 and move the decimal place here it obviously belongs.

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1 hour ago, MBDiagMan said:

You don’t need a calculator doing it my way.  Do it in your head very easily.  100/2 is 50 and move the decimal place here it obviously belongs.

I'm glad your way works for you.  a quick calculation has you 28' LOW @90kts gs, and 37' LOW @120kts.  and that's PER nm.  eh, it's close enough, right?

eman's list of people to fly ODPs with in IMC

MBDiagMan

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For a non precision dive and drive approach it’s plenty good enough.  Actually you add a little to the descent rate for that.  On a precision approach your flying the vertical needle anyway, so it’s only a guideline.  It works wonderful for me.

I’ll make note not to waste time flying with you while you’re focused on getting numbers to the last digit rather than focusing on a safe approach.

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23 hours ago, MBDiagMan said:

For a non precision dive and drive approach it’s plenty good enough.  Actually you add a little to the descent rate for that.  On a precision approach your flying the vertical needle anyway, so it’s only a guideline.  It works wonderful for me.

I’ll make note not to waste time flying with you while you’re focused on getting numbers to the last digit rather than focusing on a safe approach.

But that’s almost 400’ feet low 10 miles out on a typical dp.  It’s why they have required gradients on dp’s. You’re giving up some good safety margin there and will certainly raise concern with atc. 

Edited by RobertGary1
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You don’t need a calculator doing it my way.  Do it in your head very easily.  100/2 is 50 and move the decimal place here it obviously belongs.

Exactly what I teach as well, except I add the zero first and then take half. Of course no difference.
Totally agree the cockpit is no place to be doing complicated math or pulling out a calculator while flying IMC and keeping eyes on the instruments. Learning some shortcuts allows one to stay focused on flying and keep mental work load down. Some apparently forget this is just an approximation to help us fly a continuous descent. Still many make the mistake of using IAS rather than ground speed.

Jepp has the lead here because they publish the descent rate for several ground speeds on the plate.


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Exactly what I teach as well, except I add the zero first and then take half. Of course no difference.
Totally agree the cockpit is no place to be doing complicated math or pulling out a calculator while flying IMC and keeping eyes on the instruments. Learning some shortcuts allows one to stay focused on flying and keep mental work load down. Some apparently forget this is just an approximation to help us fly a continuous descent. Still many make the mistake of using IAS rather than ground speed.

Jepp has the lead here because they publish the descent rate for several ground speeds on the plate.


Sent from my iPhone using Tapatalk

But but but, I bought that Sporty’s electronic E6B because Hal said it would make life easier in the cockpit! [emoji1787]


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