Simviation Forums

Hello

Can anyone please describe the proper descend procedure for the 747 or other jet liners.

I read somewhere Idle throttle! is this accurate?;

I know that  you take three ceros from FL and divibe by 3  to give you the Nm to start your descend.

But how do you calculate the IAS to descend and  the vertical speed so that you achieve a smooth landing?

Is Idle throttle all the way down? and if so,  how do you maintain IAS and vert spd?

any input is well appreciated.

Thanks.

I'm lazy so I don't do all those calculations.

At FL300 start a descent 100 miles from the airport. Reduce airspeed to 200 kia and set the AP to 3-5000 ft., depending on the airport altitude.  Since you are descending your airspeed will not go to 200 kia but will remain about 275-300 kia.  When you reach your desired altitude lower your speed and extend your flaps and gear for landing.

Hey Juanca;
  check out this web site: http://www.simviation.com/fs_manuals11.htm. it has all the takeoff, approch and landing procedures.it is all so on the first page when you open simviation forums

Oh a very nice subject indeed, and quite frankly I won't be able to give you any easy answers.
The 737 can descend in many ways by using the autopilot, but only 1 of them is modelled in the stock 737's: the vertical speed mode.
By using the V/S thumbwheel you can select a RoD (rate of Descent) that will maintain a constant angle. Throttles are not at full idle, we're conducting a partial throttle descent here.
First let's assume your descent speed will be around m.76/300
I noted you were already aware of the 3:1 method to determine how far away from the airport you should start your descent....for the 737 add an extra of 5nm to slow from 300 to 250kts when passing 10.000ft. That should be fine.

So you know which technique to use (V/S) and how far away you will begin to descent...now we only need to find out what your initial Vertical speed will be.

Take your groundspeed, divide it by 2 and add a zero and 10%.
So if you have a GS of 440kts, half of that is 220...add 10% (12) =240
Add the zero= 2400

Your rate of descent will be 2400ft/min...but then you got to let speed bleed off at 10.000ft. This is in general 35nm from the airport. At 250kts

If you file an IFR flight plan in FS, you don't really need to do the whole calculations for when to start descent.  ATC will give you descent instructions.

Slightly aside from but related to Silver's response, in the real world ALL heavy flights are IFR including approaches, this regardless of meterological conditions.

Procedures vary, but AA's calls for controlled arrivals along preplanned routes and precision approaches (autopilot) to DA.

BTW, I am not an airline pilot and did not sleep in a Holiday Inn Express...but I pester and live vicariously through such people.

The Dragonfighter

One more note: If you're short on space and flying fast in a 747 AND you're on idle throttle you can use spoilers (35-40%) to decrease your airspeed without having to decrease your VS rate.
And usually the 747 won't get under 270 knots without the spoilers deployed (Kinda heavy bird!)
Press F1 for idle throttle and use your MOUSE to deploy spoilers smoothly (NOT /)!
And remember your vertical angle should not go under -5 degrees! If you want a realistic descent.
That's all I can help u with.
Good luck!

This and other FS9 answers are included in the program. Using Windows Explorer (if not using  in FS9's F10 key --kneeboard) open FlightSimulator 9/FSWeb/Learning Center/B747/FlightNotes. Everything is there.
Enjoy,
Bill
here's the link to the [url]file:///C:/Program%20Files/Microsoft%20Games/Flight%20Simulator%209/FSweb/LearningCenter/Aircraft/FlightNotesBoeing747-400.htm#Descent[/url] link but it may not display properly here

RIGHT ON NEXUS!!!!!!!!!!!!!!!!

thank you very much for taking the time. i really appreciate it.

this is just what I was lookin for.  I always try to fly as close to the real thing as possible. (and sure you too)

Thanks

No problem Juanca, that's what this forum is all about  :)

ok just one more question......


Ok,  im flying at 24000 ft and 290 IAS. (e.i)

I start my descend at aprox.  80Nm from destination
I also trim pitch to maintain 1980fpm. BUT.....my IAS increases too much!!! and if I reduce vert spd iI will end to high,  and reducing throttle to IDLE  doesnt help also.  please help me

tell me what am I doing wrong?


Thanks

hey Pal..I recreated your scenario with the default 737-400.
At 24.000ft, I had an IAS of 290 (Groundspeed 424kts)

By using the formula above, my vertical speed should be around 2300

I managed it to work very well (nice work MS programmers )

even though I was VERY heavy (95%fuel left) I flew it without autothrottle, LP compressor (N1) at around 40%, had no problems with keeping the airspeed, even down to 10.000ft where I decel to 240kts...

Here's a screenie
:

Don't know why it didn't work for you?

ok ok    Ill  give it a shot

thanks for your time again.