Descending

When descending to 2000-1500 feet, what should be my fpm?

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Depends on what your flying and where your destination is but most commercial airlines would be around the 900 fpm mark. Which is pretty standered for final decent.

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What aircraft are you flying…? You left out the most important aspect. Regardless, there will be a lot of variables to this answer…

To determine your descent rate on a 5% glide slope, you just use the following formula:

Descent rate = 5 x GS

Therefore, you should get roughly 450ft per minute for GA aircrafts and roughly 700ft per minute for airliners. This value will depend on the wind too: a headwind involves a flatter approach.

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Check this document, specifically ‘Appendix A’

It’s much, much higher than 700fpm on initial descent. Don’t confuse final approach.

If a 737 at 34,000 feet was to descend at only 700fpm, it would take 49 minutes to reach Sea level…

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That’s why I said ‘on a 5% glide slope’… Read first, comment after.

On initial descent, value really depends on the aircraft and on the situation (distance available, ground speed…). Never exceed -750ft per minute in an unpressurized aircraft (not a structural limit though).

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I’ll just take that as a ‘yes, 700fpm is incorrect, and I shouldn’t have stated the exact figure of 700fpm because the kid asking the question (no offence, you’re one of many, I’m just assuming due to the actual question at hand) likely doesn’t understand a 5% {degree I think you mean? I could be incorrect here but I’m not sure what you mean by %} descent profile (glideslopes relate to ILS / final approach)’

Anyway, good talk.

As a rule of thumb, based on a jet airliner I will normally use the below. However there are various factors to take into consideration, not limited too but including weight, final altitude, temperature, ATC instructions etc etc. Finally if you use the ‘Search function’ you will find various other discussions on this topic which will give you lots of info.

Descent Rates (based on no ATC instructions for speed)
From Cruise to 10,000 ASL : VS-2500, SP M0.69 / 260kts
From 10,000 ASL to 3000 AGL : VS-1500, SP 220 kts
From 3000 ft AGL to 1500 AGL : VS-1500 Sp 190 kts
from 1500 AGL to 0 AGl :VS -700 (depends on flare height etc) SP 150kts to Vref + 5kts

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5% is the gradient for a 3° glide slope which is the typical glide slope for airplanes. Having it the slope expressed in % is much easier as it enables the pilot to determine the appropriate vertical speed straightaway.

You can either call it a 5% glideslope or a 3° degree glide slope, both means the same. To convert 5% to degrees, you can either use trigonometric formulas or the following rule of thumb:

Degrees = % x 0.6
% = degrees x (6/10)

For the reminder:

image

Concerning the 700 feet per minute thing, it’s an example. In this case the ground speed would be 140 knots.
For final approach, just use the formula and you’ll do fine.

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I’ve seen planes (airliners and freighters) coming in at -2000-3000 fpm.

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Indeed they do on the initial descent I thought the question here was from 2000 down 1500 and not down too 2000 – 1500 ft so I was assuming they are on final in which case -2000 / -3000 fpm would make a rough landing to say the least. Somewhere around 1500 makes a nice smooth approach then down to around 900 for final. As has been said though it depends on a lot of factors distance speed etc etc. Try using the APPR and take note of how this approaches and you can use that as a rough guide or use the rule of thumb, half your ground speed is roughly what you want to be descending at. example, G/S is 140knts divide by 2 = 70 add a zero and you have 700 FPM. It’s a very basic way but it’s pretty accurate and wont bog you down with maths when you’re trying to fly.

To answer your question simply, basically you need to work with TOD if your wondering on high altitude descents.

If we are focusing on a approach descent first figure your landing speed before than finding the glideslope. I’m just making this simpler… try hand flying your aircraft on final and maintaining the glideslope.

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How far from your destination?

MaxSez: Now we’re takin aviation! It a real pleasure to finally brake out of the BS Clouds/Scud so prevalent here!

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Usually planes will descend at -2 or -3 degrees which is depending on AS and GS. Example would be Boeing 737 thats 100nm away and at FL300 you would most likley decrease speed and ddescend at -1500 to -2000VS depending on what your configurations are.

Hope this helped! :)

a few more ‘rule of thumbs’ for you! use the search function to find more useful tips!

Calculate your Cruise level = Total Distance from Flight plan / 7 = you Flight Level. (eg Total distance is 140 nm / 7 = 20 = FL200)

Calculate your TOD = Flight Level / 3 = Distance to Go to start your descent. (eg FL 200 / 3 = 67 nm)

Happy Landings

You sure you have the right person?

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What I meant from that was how far away was he from his destination, :)__

I say he put it best. Follow this and you’ll be golden

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