In turbines when coming out of the Flight Levels, what is normal VSI on a descent. I know FS defaults to 1800 on the autopilot but is this accurate?Read about the Gulfstream crash into Aspen a few years ago, scary reading the CVR beytween co-pilot and pilot, forcing the landing when planes ahead were calling the missed approach.Anyway, they were flying a stepped VOR/DME I believe. I know there are minimum clearing altitudes on the step down but just curious...when they are cleared to lower what is typical descent VSI? Do you almost dive bomb to your lower altitude when you are trying to get visual (seemed like they almost were)?Or is there a VSI on the plate that says what descent to use to assure that you do not cross below minimums?Thanks All!

Depending on the kind of approach there are indeed figures on the approach plates that help with finding the correct VSI. On ILS approaches it's usually a 3

Normally you will plan your descent to arrive at a certain point. You will take your ground speed in the descent so that say if you are descending 12000 feet and have 40 miles to do it in and your aircraft is knocking along at 300 kts you know that roughly you are going at 5 miles per minute.You will be at the point you need to have lost 12000 feet in 8 minutes.Divide 12000 by 8 and it gives you 1500 fpm.You will need to watch your speed depending on how smooth the air is and the limitations of the aircraft and adjust the speed with the power you have set.Also in a prolonged descent you will find that the winds will change direction and speed so that you may start with 300 kts and find your groundspeed drops.If that is the case you can reduce your decent a little as it will take longer to get to that point.If the winds come more onto your tail you may find you are going faster and can increase the descent rate.You are literally monitoring the trend of the aircraft and adjusting accordingly.On step down approaches you will have points marked on the chart. As an example you may find that you are tracking a VOR/DME on a particular radial the step down may be marked as 6000 feet ASL until Vor ABC 40 dme. The next sector of the step down may be marked as 4000 feet ASL until Vor ABC 20 Dme.You can desend as fast as you want after you pass over the 40 dme point as long as you do NOT go below 4000 feet ASL until you get to the next descent point.May I add that in any flight you are planning to make the flight as smooth as possible for your passengers and using the inheritant energy in the aircraft to make the flight as efficient as possible.There are times when your plans go out of the window when ATC want you down quickly by a certain point or hold you high for longer than you desired because of other traffic below.In the Citation Bravo I fly we aim for 2000 fpm but that can vary from as low as 1000 fpm to 6000 fpm if needed although you wont impress the passengers ;-)Hope this helpsPeter

On the approach plates vertical profiles are shown for minimum altitudes at each checkpoint position. In addition other restrictions might be shown.A normal ILS or calculated final gradient is around 3.0 degrees offering a mild descent to transition to a gentle landing flare. The terrain at Aspen is full of terrain obstacles on the final approach requiring in the last stages a descent gradient of 5.x degrees. This accident profile was published in Computer Pilot a few months ago with instructions how to emulate the approach in FS9 using varying weather conditions.If even slightly below the published vertical profile it was shown that the line-of-sight VOR transmission could be blocked, not a good thing in poor visibility, which if used would cause loss of DME which would then force the use of a timed descent. The use of a timed descent is not as accurate as a VOR/DME descent requiring higher minimums, and a VOR/DME descent is less accurate then a precision ILS/GS descent.The accident simulation published in CP estimated that the pilots lost sight of or did not see the runway at the most critical time nor meet the new minums published (via NOTAM) for that situation.As far as determining the descent rate required for a fixed approach descent angle there are formulas available based on your ground speed and angle required to calculate the rate of descent.You might find it of interest to purchase for your area of interest one hard copy publication of the FAA approach plate booklet (about $4.50) at a local pilot shop. These cover a wide area and include a rate of descent table in the appendixes. You can also purchase CD collections of current plates from the FAA or outdated collections from various vendors. Free approach plates can be found on the web from FAA and other sites. Search on these forums for "approach", "plates", etc. I do not have the location of the descent table published on the web. The FAA site does have the Instrument Flying Handbook published on the web as well as it being available from book stores or the FAA in hard copy - a very handy tutorial and reference.

You seem to be asking two questions:1) How to judge the descent from the cruise FL.2) The best approach angle.1) This has been described to me as one of the more difficult airline manouvres to get absolutely right. Many will be thinking...why? If you want to fly like an airline captain, then when ATC tells you something like descend to FL95 12nm before CPT you must be at FL95 12nm before CPT. Not 11 or 13. In addition, your employers will expect you to be idling all the way down to save fuel. It is a shameful thing to have to apply the speed brakes as that means that you were in the cruise for too long. Likewise, if you have to open the engines up a tad to arrest the descent as that means you wasted some fuel on the way down. I exagerate a little as clearly, with an FMS then it is pretty straight foward. But for those still plodding around in 737-200s it is no laughing matter. You are limited only by your limiting speed and how high the gin is in the PAX's glasses. There is one other limiting factor that is usually ignored. The maximum cabin pressurisation rate is equivent to 500fpm on the way up and 300fpm on the way down (for passenger comfort). Generic figures are a max pressure ratio of 8:1 and a maximum cabin pressure altitude of 8000'. Therefore, your descent is limited to no exceeding the 8:1 ratio and keeping the re-pressurisation of the cabing to 300fpm max.To answer your question, 1800fpm is not realistic as it depends...2) VOR/DME or event NDB/DME (non-precision) approaches arn't handled like constant g/s ILS descents. The difference is that on an ILS you descent to descition height (DH), and if you can't get a visual reference you go around. When doing a non-precision approach, you descend as quickly as is safe to the MDH (minimum descent height) and then remain at that height until you either make visual contact with the terrain or you reach the MApt (Missed Approach Point). If you reach the MApt first then you go-around. You maybe stepped down to the MDH by ATC or the procedure (depending on if you are vectored or following the plate), in which case you follow the minimum heights as described on the chart or dictated by ATC. At somepoint they will clear you to descend with the procedure anyway. Most plates do provide sample descent rates. The descent angles on non-precision can be 5.5deg and are advisory. To answer your question, you are limited by the approach speed of your a/c and the minimum step down heights - there is no point arriving at an intermediate height early and there in the high pressure world of commercial aviation where go-arounds cost money, you maximise your chances by getting the MDH as soon as you can, once you have vis with the ground you can attempt maintain it and secure a landing.RULES OF THUMB:* To calculate your TOP of Descent (TOD):i) Multiply your altitude by three. That gives you the distance to start your descent. Provides the answer in nm. So if you are at FL350 and need to be at FL95 then (35-10)*3=75nm.ii) Divide your groundspeed by 2 and multiply by 10. That gives you your approximate rate of descent (ROD). Provides the answer in fpm. At 300kts, you need (300/2*10) = 1500fpm.* To calculate your approach ROD:i) Multiply your approach speed by 5 (divide by 2 and mult by 10 if you prefer). Provides the answer in fpm.

Hi there. I hope I'm not teaching my granny about the egg business but I just want to mention this! If you set a route up and include some intersection points on your way into the destination airport the kneeboard will show you the height to be at for each intersection point you have added to the route. The more you add the more accurate your descent. If you fly with the gps these same intersection points are shown on the screen as you travel and you can therefore judge your descent between each point on the course. This is quite like the approach plan shown at the bottom of a chart and to my amateur mind is almost like having charts to all the fair-sized airports, and can be helpful in getting into awkward places, so long as there are some intersections to work with!:(

In regards speedbrakes, I have heard RW flightcrew describe them as being "for my misjudgments, not ATC`s" when asked for impractical descent profiles. Nicely put!

HiWe tend not to use speedbrakes as they do make quite a bit of noise in bizjets.yes you are right that they also say that we havent worked the profile right.The Citation thrusted right back will come down at 6000 fpm without busting the speed limits.Having said that we do have an empty aircraft at times and when the cats away the mice will play like extending the Gear at 250 kts ;-)which is allowable but incredibly noisy and causes quite a pitch up.Again something you wouldnt do with passenegers drinking their cocktails in the back.Peterhttp://forums.avsim.net/user_files/98721.jpg

Guys, thanks for your great answers!Only comment is that I am pretty busy running the aircraft...single pilot IFR and not much time to do all thes calcs (maybe I answered my own question and should do the calcs in the pre-flight)!Thanks again...very informative.

>Guys, thanks for your great answers!>>Only comment is that I am pretty busy running the>aircraft...single pilot IFR and not much time to do all thes>calcs (maybe I answered my own question and should do the>calcs in the pre-flight)!>>Thanks again...very informative.The problem is :-) that you have to do all these calculations single pilot IFR.I fly the Citation Bravo two crew but many fly some of the citations single pilot.I also fly two Seneca Five twins single pilot and the same principals hold although at slower speeds.On your IFR test you will be expected to fly the aircraft without autopilot within the tolerances expected and also have to navigate and do such calculations.Many people have their own formula for easely working this out mine is to think of speed in blocks of 60 kts or 30 kts ie 90 kts is 1.5 nm per minute still air.Remember to that this isnt an exact science so close will do as you will be adjusting for differing winds etc anyway.Peter

>Only comment is that I am pretty busy running the>aircraft...single pilot IFR and not much time to do all thes>calcs (maybe I answered my own question and should do the>calcs in the pre-flight)!Hi Greg. Here's what I do in the sim. Assume that I am at FL270 and plan on landing at an airport which is less than 500' above sea level.I plan to decend about 3000' every 10 Nm. Therefore I divide 27,000 by 3000 and start my descent 90 Nm from the airport. My initial descent is 2000 FPM and I limit my speed to 300 KIAS. Remembering my formula (3000'/10 Nm), then 80 Nm out, I should be at FL240. Seventy miles equals FL210, 60Nm equals FL180, etc.If I were within 70 Nm and I'm still FL230, I'll change my descent rate to 2300 FPM. If, on the other hand I'm at FL190, I'll adjust to 1700 FPM. Every 10 Nm, I monitor my descent and adjust if necessary.At 15,000', I begin to slow down (aiming for 250 Knots at 10,000') and decrease my rate of decent to about 1200 - 1500 FPM and continue to monitor my altitude every 10 Nm. At 30 Nm, I slow again aiming for 220K when I am 22 Nm from the runway. Now I adjust my descent rate to be 6000' above the runway elevation when I get 20 Nm out. I slow to 180K and descend at 300-500 FPM unilt I capture the localizer and then level off until the glide slope comes down to me.So how do I, "do all thes calc"? I use a calculator; my fingers. If I'm 30 Nm out, I count 3, 6, 9(000). If I'm 50 miles out I count 3, 6, 9, 12, 15(000). If the airport is more than 500' above sea level, then I'll add that number to my 3, 6, 9, ... calculations.I still do the same calcs and rate of descent adjustments even when FS9's ATC is calling the plays. As long as you are dropping at least 1000 FPM, ATC is happy. And even if you descend slower, they will not cancel your IFR because you are descending too slowly; they just nag you over and over again. It works for me. R-

Thanks again everyone!I was going to ask what about when ATC brings you down...but you did anser it in that you should monitor to ensure you will get to cleared altitude properly and on time.By the way, ATIS are in MSL or AGL? I believ AGL, correct?Thanks.

>>Read about the Gulfstream crash into Aspen a few years ago,>scary readingthey demonstrated how NOT to fly an approach. Michael J.WinXP-Home SP2,AMD64 3500+,Abit AV8,Radeon X800Pro,36GB Raptor,1GB PC3200,Audigy 2

>>By the way, ATIS are in MSL or AGL? I believ AGL, correct?>not sure what you mean. When ATIS reports weather ceiling at the airport it is always in AGL. Michael J.WinXP-Home SP2,AMD64 3500+,Abit AV8,Radeon X800Pro,36GB Raptor,1GB PC3200,Audigy 2

AGL, that's what I thought.Thanks.