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Ant1981

Decent rate

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Is it me, or do other people feel they are being given instructions to decend to the crossing restriction altitude a little late for some aircraft decent rates?

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Is it me, or do other people feel they are being given instructions to decend to the crossing restriction altitude a little late for some aircraft decent rates?
Without knowing more information it's hard to know why you are having this problem. I've used RC with many large aircraft - B737, B747, B777 and Concorde and can always meet the crossing restriction.What aircraft are you using?

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Without knowing more information it's hard to know why you are having this problem. I've used RC with many large aircraft - B737, B747, B777 and Concorde and can always meet the crossing restriction.What aircraft are you using?
Various aircraft from 737s to A340s, what's your typical decent rate?

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Is it me, or do other people feel they are being given instructions to decend to the crossing restriction altitude a little late for some aircraft decent rates?
what descent rate are you having to use, to make the crossing restriction.

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Often -2000ft/m to -2500ft/m, which seems a little steep, I even slow the aircraft down, which when you think about it, would make the decent steeper.

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Various aircraft from 737s to A340s, what's your typical decent rate?
Usually 2000-2500fpm which is much the same as yours. If you use the CDU/FMC you can program a 40-mile waypoint and put an altitude restriction of 11000/12000ft into it and your CDU/FMC should control the speed and rate of descent to meet that requirement.Are you overspeeding during the descent?
Often -2000ft/m to -2500ft/m, which seems a little steep, I even slow the aircraft down, which when you think about it, would make the decent steeper.
Not really. Aircraft are at their most efficient when high up so they stay up there as long as possible. Concorde descended at 3500fpm but most of the passengers were probably well fed and watered so never noticed! :(

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Usually 2000-2500fpm which is much the same as yours. If you use the CDU/FMC you can program a 40-mile waypoint and put an altitude restriction of 11000/12000ft into it and your CDU/FMC should control the speed and rate of descent to meet that requirement.Are you overspeeding during the descent?Not really. Aircraft are at their most efficient when high up so they stay up there as long as possible. Concorde descended at 3500fpm but most of the passengers were probably well fed and watered so never noticed! :(
Yes, I know aircraft are more efficient when high up, wasn't talking about cruise altitudes, least I don't think I mentioned it.I just tried again in an A330-200, decent rate of -1800ft/m and it worked fine. I can come close to the speed restriction at times, but nothing too bad. I'm now wondering if it's anything to do with the flight plan as entered into the FMC, as you say also. I'm using FS Commander to create plans. I'll make sure the plan has the aircraft selected as I'm thinking that dependant on aircraft specs, the top of decent will differ for the same route with different aircraft.

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Yes, I know aircraft are more efficient when high up, wasn't talking about cruise altitudes, least I don't think I mentioned it.
You didn't. :( I only mentioned because the descent rate is affected by how long you stay at cruise.
I just tried again in an A330-200, decent rate of -1800ft/m and it worked fine. I can come close to the speed restriction at times, but nothing too bad. I'm now wondering if it's anything to do with the flight plan as entered into the FMC, as you say also. I'm using FS Commander to create plans. I'll make sure the plan has the aircraft selected as I'm thinking that dependant on aircraft specs, the top of decent will differ for the same route with different aircraft.
Yes, selected aircraft will be important. If you can insert an additional waypoint for the crossing restriction it may help. Alternatively, use the FIX option on your CDU/FMC to display an circle 40 miles from the arrival airport and adjust your descent rate accordingly.

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Alternatively, use the FIX option on your CDU/FMC to display an circle 40 miles from the arrival airport and adjust your descent rate accordingly.
Thats what I do in the Boeings, too bad the MD11 doesn't allow fixes to have distances (no circles) :(BTW I don't have any problem with the decent rate required.

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Do you always descend at the aircrafts maximum descent rate?
Not sure who that question is directed to. No, that wouldn't be very good for the virtual passengers. Aircraft can descend up to 5000fpm which wouldn't be good from a planning point of view.If you don't have a CDU/FMC which will control the descent rate and speed use 2200fpm as a guide. Speed should be 280-300kts reducing to below 250kts once below 10,000ft (FL100).

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Not sure who that question is directed to. No, that wouldn't be very good for the virtual passengers. Aircraft can descend up to 5000fpm which wouldn't be good from a planning point of view.If you don't have a CDU/FMC which will control the descent rate and speed use 2200fpm as a guide. Speed should be 280-300kts reducing to below 250kts once below 10,000ft (FL100).
I'm just making it with those speeds and using 1800ft/m, which is specified as the descent and climb rate, so I took that as the max. So if 1800 and 2200 is fine, then all should be well.

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I'm just making it with those speeds and using 1800ft/m, which is specified as the descent and climb rate, so I took that as the max. So if 1800 and 2200 is fine, then all should be well.
throughout development, coding, testing, i use the stock ms lear. regardless of the crossing restriction (near side or far side), i always make the crossing restriction with a descent rate of 1800. as soon as i'm given the crossing restriction, i start the descent.you're playing with fire (also known as "you better be a radar contact expert, and experience sim pilot) to ask for a pilot's discretion for the crossing restriction.jd

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Do you always descend at the aircrafts maximum descent rate?
Maximum? No way! That would cause me to hold alt all the time waiting for more decent instructions.Jay V

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On a similar note, how does RC4.3 deal with STAR restrictions? From the examples below,KRDU RDU JAYRR GSO SPA ODF FLCON DIRTY BYRDS COSEL HOKIE LIAMS KATLKATL 141738Z 30011G16KT 10SM FEW020 SCT025 BKN035 18/12 A2977I'm planning on a FLCON3.SPA.27B approach. With the 09/04 AIRAC, I'm expecting a FL140 crossing restriction at DIRTY, however, RC gives me a FL120 restriction instead. Also, when making a FLCON3.SPA.8B approach, I'll get a FL110 restriction at DIRTY. From there, RC has me stay well below the remaining restrictions across Atlanta. I've figured out to add each point of the SID/STAR into the .pln, however, I was wondering how does RC4 deal with SID/STAR crossing restrictions?Cheers!!Ken

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On a similar note, how does RC4.3 deal with STAR restrictions? From the examples below,KRDU RDU JAYRR GSO SPA ODF FLCON DIRTY BYRDS COSEL HOKIE LIAMS KATLKATL 141738Z 30011G16KT 10SM FEW020 SCT025 BKN035 18/12 A2977I'm planning on a FLCON3.SPA.27B approach. With the 09/04 AIRAC, I'm expecting a FL140 crossing restriction at DIRTY, however, RC gives me a FL120 restriction instead. Also, when making a FLCON3.SPA.8B approach, I'll get a FL110 restriction at DIRTY. From there, RC has me stay well below the remaining restrictions across Atlanta. I've figured out to add each point of the SID/STAR into the .pln, however, I was wondering how does RC4 deal with SID/STAR crossing restrictions?Cheers!!Ken
this is outlined extensively in the manual, illustrated in the flight planning section of the manual, and demonstrated in several of the tutorial flights.

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Is it me, or do other people feel they are being given instructions to decend to the crossing restriction altitude a little late for some aircraft decent rates?
I typically use a descent rate in the 1500 - 1800 ft/min rangeand bring my speed down to the 280 - 300 IAS range, reducingas you descend. Below FL180 I bring it back to 270 and thatworks very well for me. I find RC to be very reasonable withdescents.Typically, one would start off with the higher rate of descent andthen reduce it as needs be which also helps in reducing speed.I.e. if I'm at FL240 and cleared to FL110 I'd start at 1800 ft/minand below FL180 or FL170 reduce to 1500ft/min and then to1000ft/min for the last thousand feet.Cheers,Jim

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If you have instances where you anticipate you will arrive high at the restriction anticipate the restriction at 12,000 feet 40 nm out (terrain permitting). You then use to rough guide of the 3:1 descent guide:"The rule of three in aviation usage refers to the "3:1 rule of descent", in that 3 miles of travel should be allowed for every 1000 feet descent." from wikipedia.You can then request a lower cruising alltitude from center by estimating a vertical profile to the restriction and perhaps starting your descent earlier or a lower altitude at each step.

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