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Guest stevepow

What is the normal decent rate

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Guest stevepow

My question is what is the normal decent rate for the pmdg 737-700. my decent speed is .76 once the 2 speeds match i then drop it to 280 knots but i need to know what is the normal decent rate?

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There is no normal - in the real world your rate is going to depend on the specific VNAV path you're following down (taking into account restrictions and such), ATC instructions, and so on. VNAV calculates by default for an idle descent, so it's basically whatever speed gives you the right glidepath down for the distance, altitude difference between cruise and the landing airport etc.


Ryan Maziarz
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Hello Steven,Ryan summed it up pretty well, weather will affect your descent rate too, with a headwind your descent rate will be less.To roughly answer your question and I mean very roughly, the higher your altitude the higher the rate will be, if I would put it in figures, considering the 3.3 rule (CRZ altitude*3.3 = Top of descent) down to about FL200 you can descend at 2500-3000 FPM, down to FL100 at 1800-2200 FPM and below 10000 feet at 1000-1500 FPM. Note that witihn these figures you will be able to maintain your descent speed.Take your weight in to account too. The rates I stated above are of course not real life, they are an average of what I get flying this aircraft.Regards

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Guest stevepow

OK i don't want to be a novice but is there a calculation that i can use to let me know. the reason that i ask is because i took a flight last night. I was at FL330 ATC told me to descend to FL290 so i did using a vertical speed of 1800 too make a long story short i was too high to land when i reached the glidscope. so is there an easy formula to use. please give an example. thank you

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Use the yellow banana on the ND by setting your MCP ALT to 29000 and adjust V/S to put the yellow arc on your target.Now, I don't understand what decending to FL290 has to do with the glideslope. You lost me here. I presume that this was much further down the road than the initial descent. If you using ATC, they should have cleared you from FL290 lower to cross an arrival gate at some given altitude... if you are using STARS and default ATC you just discovered why default ATC is useless.Top of descent distance rule of thumb is altitude change in thousands multiplied by 3, which will give you a reasonable target, but not the descent rate which depends on weight and winds. For example, at FL330 you want to descend to 10,000 then it's (33-10)*3 = 69 nm. What ever V/S is takes to come down at about 300 ft/nm will work in this case. Start at 3000fpm and adjust from there. The yellow banana makes this pretty easy.Real world ATC will step you down to FL310 to change sector controller, then down to FL230 to the next sector controller then down to 10,000 (or higher) to hand you off to approach controller. They usually got it worked out such that you are always descending and never levelling off as you work your way down from sector to sector.


Dan Downs KCRP

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Hi,As posted by others, I use the 3 to 1 rule. If your at say FL350, drop the zero and multiply the 35 by 3. This ends up at 105.So 105nm from your destination begin your descent. Now the question is, at what vertical speed?If your ground speed is 450 knots and you descend at 2000 fpm, you'll cover 7.5 miles in that 2000ft a minute descent. If your ground speed is 400 knots, then you'll cover 6.67 miles at the same descent rate.So, what you dial in as your vertical speed will get you to a different altitude in a set distance depending on your ground speed.I have always used the rule of thumb that descent rate is 5 times your ground speed. So 450 knots will be 2250 fpm descent.Use these two rules together and you won't be far wrong in being at the right flight level/altitude for the distance from destination.Stuart.


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Hey Dan,The yellow banana is for something completely different. Use the green banana instead. Much better for altitude change predictions...LOLTGIF,


Mats Johansson
PMDG Flight Test Dept
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Guest stevepow

i dont mean to sound dumb but what bannana are you talking about i dont see anything shaped like a bannana let alone a yellow one

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Steven,We are talking about the green arc visible on the ND when you climb or descend. The arc will tell you at what point you will reach the altitude dialed in on the MCP. If the arc is not visible you might need to change the range to make it visible.Hope it helps,


Mats Johansson
PMDG Flight Test Dept
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Steven,The yellow one goes for Airbus, and in cereals, occasionnally:)The one mentioned is a light green arc which appears on the ND when the aircraft changes pitch according to the MCP altitude. It roughly indicates the point where you'll achieve your target altitude whether you're descending or climbing.Check out the screen shots forum for PMDG 737's you should be able to see it in a panel shot :D EDIT: Mats, you just beat me to it!!

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"If your at say FL350, drop the zero and multiply the 35 by 3. This ends up at 105, So 105nm from your destination begin your descent. ".... assuming your airport is at SEA LEVEL. If you're landing at Denver, Johannesburg, etc, you're going to be too low. Also, RW pilots add 10 or more nautical miles to their calculations for slowing down the aircraft.Forget vertical speed... descend with the throttles at idle. VNAV, if programmed correctly, and FLCH will give you an idle descent. Idle descent is the most efficient.Cheers.Q> Ян

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>I have always used the rule of thumb that descent rate is 5>times your ground speed. So 450 knots will be 2250 fpm>descent.>>>>I learned a slightly different method in flight school, but still gets you the same number. I was taught that if you take your groundspeed, in this case 450 kts, and add a zero and divide by two. So, 4500 / 2 is 2250. Same thing, just a slightly different way of getting the number.


Sean Wood

Rock Island, IL

CPL-ASEL, AMEL/IR

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Your quite Qavion.I forgot to subtract airport altitude from flight level.....Good job I only fly PA28's and Cessna 152's aint it?Stu


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Guest stevepow

can someone show me a picture of the nd with this green bannana you guys are talking about. also is it normal to descend with the throttles on Idle? and at what point do i put the throttles back to normal. one thing i notice wouldnt a 2250 FPM make the passengers throw up all over the place??

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>Use the yellow banana on the ND by setting your MCP ALT to>29000 and adjust V/S to put the yellow arc on your target.Yellow?? Oh darn I must be color blind as it always appears green to me. Oh well off to the docs to have it checked tomorrow.John Veldthuishttp://www.virtualpilots.org/signatures/vpa475.png


John Veldthuis

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