How do I know when to descend coming in to an airport?
The general rule of thumb I use is around 30 minutes before for something like FL350 and up to 40 mins before for FL430 (assuming that I’m flying 737ish or larger). Using the STAR preset altitudes should be good enough, but make sure to pay attention as some can be a bit crazy…
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For me when I cruise at 36,500 I’ll start to descend when I’m around 120 NM out from the airport and descend to 3500 for final approach when lining up for landing on the runway at the destination airport.
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Thanks so much to both of you!
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By using Top of Descent (TOD) , theres stuff out there you just have to look, heres a video from infinite flight on how to do it specifically in IF
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I usually set it to VNAV and let the waypoint conditions decide my descent as in some airports, there might be terrains at lower altitudes.
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Set VNAV and the A/P will descend for you. The other way is to substract from your cruise altitude the one of the final approach point, and divide the result by 300.
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If you’re striking for realism use FR24 so you can learn about the aircraft capabilities and the approach plates. Always aim for efficiency when you’re not on controlled airspace. This includes using shortcuts whenever possible. Personally I use the kind of approach that depends on the airport like steep descent or shallow. Also make sure to keep an eye on the load of your aircraft during descent if you’re slightly heavy or just below mlw go for a shallow descent to help you burn more fuel.
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This I would recommend as well but if you do have access charts that would be slightly better to be on the safe side.
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I usually have vnav but I think for more realistic you probally should do 30 to 40 min before with -2000 v/s
I use FR24 and estimate where the area they descend. -2800fpm should be fine occasionally. Steep but quite effecient.
Hi, as 40,000feet and 30,000feet at 1000fpm take 40min and 30min respectively, picking 2000fpm as a roughly reasonable target average, means starting descent 20min out for FL400, or 15min out for FL300.
And mentally subtract off a bit for the airport pattern or ILS intercept altitude etc. as necessary.
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Thanks! (10)
Here’s my simple tactic:
multiply 3 times of your cruising alt + extra 20nm
descent between 1800-2200 fpm @ 270-280kts
So say if you’re 200nm away from KSFO, and your cruising alt is @ FL320
so 32 x 3 =96 + 20 —> Descend starting at 116 nm away
Depending on winds, if encountering a headwind you may have to increase your airspeed, and the opposite goes with a tailwind. 
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You are still missing the point regarding how aircraft descends. Narrowbodies can quickly loose alt while loosing airspeed but Widebodies can’t. Also if you were to descend at 116nm from FL320 you’re not taking into account of the aircraft flown, or sudden wind gusts that can possibly make you higher on profile. You should be aiming for a specific alt and waypoint to leave some margin if required.
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I saw a post that said "Cruising Altitude (35,000ft - airport elevation (200ft) x3 = 35,000 - 200 x3 = 104.400 divided by 1000 = Start descend 104nm before Airport. Is that correct?
Well this is my advice you gotta aim for an alt and waypoint which is usually the initial star approach waypoint and descend based on the alt preset given. For example in hubs like OMDB VUTEB is the waypoint at 11,000ft. What it means you should be at 11,000 or less when you approach VUTEB fix and if you refer charts for this airport you can find speed restrictions given in this case it’s 230kts or lower. This method can be done using vnav or manually control your v/s if you’re experienced. Now for airports that usually lack a proper approach procedures you should find a waypoint which is far enough from the final approach. This helps me to make things more flexible if I were to take shortcuts for the approach.
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