# When should I descend

If I’m flying at fl380 then at what distance should I begin descending?

Use Vnav and procedures in app

Try using VNAV, it can calculate all of this for you. Im sure there are guides for manual calculations, i need to find a link

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You can use the VNAV

Always depends on the height you are at. Generally I use the VNAV to descent me to about 10,000 feet. It’s always a challenge to find a good waypoint to set the VNAV to 10,000 But I would Go on the solo server to practice at different airports with different waypoints to get the hang of it.

See this tutorial:
VNAV Tutorial

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VNAV is always a good choice. However I prefer an idle descent. So I’ll kind of gauge it in a way that if my speed is above 500 kts because of a tailwind, I’ll make my TOD 110-120nm Dist. To Dest. If I am slower than 500 kts I’ll make my TOD 90-100nm dist. To Dest. Controlling my speed on the way down using VS.

How do I make a procedure?

Hello, usually the VNAV function will decend for you. However you can decide what altitude you want to decend let’s say you approach KJFK ILS 22L from Dubai on the Emirates A380. You may arrive Via PARCH3 arrival or if you don’t have a STAR it’s fine. ATC does recommend Arrival procedures since they have decent altitudes. So use STARS . If you already do make sure you arm your VNAV at least 30 minutes away from landing. For me I put it as soon as I reach my cruise just In case I don’t wake up in time during long hauls. But try using the VNAV is if you haven’t already

Check this tutorial

In general, multiple your altitude in thousands by 3 to get the distance in nm. i.e. 38x3 = 124nm.

Don’t do this! This could lead to you descending without clearance, or getting an overspeed violation below 10,000ft.

how do I do that without an ILS

If there’s center active I will turn off VNAV but most of the time approach is active. If I don’t activate it I will fly too high and they’ll ask me to expedite altitude change and could get a violation for not following assigned altitude

If you request to descend via a certain STAR, then they’ll let you use VNAV according to that STAR

I set a certain waypoint and altitude that I need to want to decend down to, and I do it like 2-3 mile waypoint away from the destination airport

Before the vnav functionality was implemented in 21.1, I used to use this formula to calculated my TOD. This is ((Initial Altitude - Final Altitude) / 1000) * 3) to get your TOD distance in NM. Let’s say your altitude hold for a STAR waypoint is 21000 ft and you are cruising at around 38000 ft. By the formula ((38000-21000) / 1000) *3 you would get 51 NM out from the waypoint before you would need to descend.

Furthermore, you can calculate your rate of descent by using this simple formula, (Ground Speed * 5) So if you are doing 550 knots GS, by the formula your rate of descent would be -2750 ft/min.

I prefer using VNAV for landing, using an approach procedure (you request apparoach via gps to the controller). Simply set the vnav waypoint to around 10 feet above the final point and your plane should gently float down to the runway!

Can we still descend manually ?

Yes you can still decend manually.

Ok thanks a lot :)

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