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Hi guys!

So as a follow up on my previous post regarding the 737. How/where would I determine the point in time to which I need to start descending?

Example: If I were doing a flight from KOAK to KLAX in the 737-700wl, at a cruz alt of FL250 (how would I determine the cruz alt and cruz speed for a flight???) where wou8ld I start the decent so I would catch the ILS at the right point?

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Are you flying in a payware 737 or default? (does it have an FMS)

Regardless, good rule is 3:1.  For every 1000 feet you plan to descend you need 3 miles (speed 280 knots is probably a good number to use with a descent rate of 2000 ft/min).  So to go from 25000ft to 3000ft to join the ILS you need 22x3=66 miles.  You can give yourself some extra space and start to descend 80 miles from destination.

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I am guessing you are in the NGX because it is in this forum.

You should really read the manual or do the tutorials, I hate to say that but it would answer you questions and many more I'm sure. Even if you only did the tutorials.

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Here is a formula for you to use:

1.To calculate when to start your descent = 3x Altitude required to lose then remove the zeros

2.To calculate the rate at which you need to descend = 1/2 Groundspeed + 0

Example:

Crossing restriction - Cross the LON VOR at 10,000ft

You are cruising at FL350 and your groundspeed is 400knots.

1. You need to lose 25,000ft (difference between FL350 and 10,000ft) x 3 = 75,000 remove the zeros = 75

So that means start the descent 75nm from the LON VOR

2. 400knots Groundspeed divided by 2 = 200 then you add one 0 = 2000.

So that means your descent rate should be 2000FPM

Hope that helps

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Yes, I am talking about the PMDG 737NGX.

And thankyou for the equations guys.

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You really need to read the manuals buddy. When the aircraft is correctly configured it works that out for you.

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Yep. LNAV/VNAV with all the weights, a proper arrival set etc.

*10 miles from top of decent as predicted by the FMS* you will get a "bing" noise and a yellow light on panel "FMC Message". The FMC will state something like "Reset MCP Altitude".

At this point you (request to descend) and change the altitude window on the autopilot Mode contol panel (MCP) to the altitude you were cleared to descend to by ATC (or if cleared to leave controlled area on descent - to the Minimum safe altitude).

After that the aircraft will remain flying level for a little bit (aka 10 miles) and then all on it's own, it will start to descend. It will continue descending till it reaches the altitude you set in the MCP and then level off. If you change the MCP altitude setting before it levels off, it will continue descending to the new altitude.

If you are on an RNAV STAR that feeds onto an ILS approach, have either the wind prediction set up for descent before you began descending, or you are descending into a headwind, then the aircraft will set itself up at 220kts ready to intercept the ILS. You will then need to press the "APP" button and watch itself descend with the ILS Glideslope. After that you do all the things you need to do to land. (Flaps, Gear, Slow down, Arm brakes/spoiler, actually land the plane etc).

That's right, the plane should be entirely capable of flying from 39,000ft down to 3000ft above airfield height on autopilot LNAV/VNAV with the minimum of intervention, and never leaving LNAV/VNAV modes.

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I am aware I need to read the manuals everyone. -_- i will start reading them.

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If you don't have the time do the tutorial flights first.

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I am aware I need to read the manuals everyone. -_- i will start reading them

At least, fly the tutorials. It will be life changing

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At least, fly the tutorials. It will be life changing

Agreed, I have not read any of the manuals except the intro and the two tutorials (which I failed the manual landing in #2 badly by not actually turning tight enough or something).  I gained enough combined with previous simpler payware addon use to set up my own flight the other day.  I didn't have the nice elaborate to/from routing (it all turned into "direct to" points based on the route I made in the FSX planner) of the tutorials and did a wild guess on the de-rate but I got off the ground and into VNAV/LNAV beautifully even with using FSX ATC vectoring to my path instead of a SID.  Too bad FSX saved corrupted versions of my flight after I got to cruise altitude and I never got to finish the flight :( (loading would hang at 6% loading scenery objects).  I definitely plan to start skimming the rest of those manuals though.

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