# It’s not about the Vertical speed!

Hello everyone!
I just wanted to make this post to mention, or remind people, that the V/S (vertical speed), is mot the important thing for a steady climb, descent.

During climb and descent, in most cases, pitch for airspeed, power for altitude, sort of. Even in an airliner, it’s just a big Cessna.
So, during climb, try to maintain a certain airspeed and thrust setting, and change the vertical speed continuously to maintain that IAS and thrust setting. Usually during the climb 80% to 90% N1, not throttle, N1, is good. Whatever V/S that gives you, use that, but still keep changing it for different winds and air densities as you climb.
Oh, and here is a tutorial that Tyler made using this method.

And, now the descent.
Firstly, just to make 1 thing clear, this method typically I found only works if you use the 3x1 rule, which you can probably find a tutorial on somewhere. Let’s say I am at FL330, forgetting winds and weight, I will start my descent 99NM out. Oh, and by the way, that is 99 track nautical miles, not direct.
The first thing to do, is to reduce the thrust to 0% throttle. You do this because what you want to do is to perform a near idle “CDA” which is a continuous descent approach. This helps to burn less fuel, which of course lowers the chance of a low fuel scenario, lowers the amount of CO2 in the virtual environment, and, lowers the amount that the operator has to pay in virtual fuel.
Basically, the concept is is that you don’t let that throttle get to high until you are established on the glideslope. So, the same thing as before in the climb, pitch, or change the V/S, to maintain IAS and 0% throttle. I asked a 737 captain IRL, and he said that a descent of up to -5500FPM would be considered routine. Of course, that does vary on aircraft type.
As you pass through FL280, FL200, and 10,000ft, be warned, in IF, the air density increases very quickly and suddenly. This means you need to raise the nose, or raise the V/S, to continue to maintain your IAS. Of course, before going below 10,000 you need to slow down. So, keep the V/S closer to 0FPM, while slowing down. If ATC have already instructed you to descend below 10,00, if possible, atleast try to descend at atleast -500FPM. If you can’t because you need to slow down though, you can’t. Typically though, you should be able to, although it might require speedbrakes.
That brings me on to my next point, speedbrakes. Use these at minimal. Don’t use them for the sake of it. Only use them if you are too high/fast, or if you want to keep descending and still reduce IAS at a high rate of descent for whatever reason.

Now, obviously, you still need to intercept the glideslope from below. There fore, you will need to level of. But from that point, you don’t want your throttle at 0%. If it is at 0%, that is a clear sign you are unstabe. So, Go around!

I hope this makes sense. Do feel free to ask questions!

Was this helpful and did you understand? If so, rate it on a scale of 1-10, 10 being great. Thanks

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also, I would have put this in #tutorials, but I wanted to say this. And, I have seen tutorials go in #general, so I thought it would be ok. Or a few anywat.

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i’m surprised how no one has replied yet… haha. Nice topic! thank you for the tips

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Thank you very much!

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Nicely said. I will add a few notes:

1. You’re right that the power is a bit higher than you’d need but that’s intentional and realistically simulated (except the 757 which I think is way too much). Jet engines are max rated with thrust about 110-120% of what’s required for normal operations which can be useful during emergencies such as windshear or stall.

2. I believe the math on your 3x1 rule should be closer to 110 nm but don’t forget to also add about 10nm to account for that slowing down to 250 at 10k feet. So about 120 nm would be a more conservative TOD.

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Yeah, I know. What I mean is that I find that say 90% N1 in IF is the equivalent of like firewall , so like 104.5 I think in the 737, in real lufe. If that makes sense. I know that’s why it goes over 100% N1.

As for your second point, I’ll look into that. Thank you!

If I’m being completely honest, I didn’t read the whole thing, but this quote right here is really true. When you’re flying a heavy 747, climbing at 2500 fpm will have some major pitch issues and your nose will be wayyyy up in the sky. But if you’re in a 757, 6,000 FPM and the nose barely points up (because that plane is soooo messed up)

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You’re right and we have limitations to prevent that. I can give an example for the aircraft I fly (CRJ2), our firewall Is roughly 98.6% N1, our limitation is to not let it go above 96.2% for takeoff and our usual max CLB N1 isn’t much higher than 95%. Idk what the CRJ2 can actually firewall at in IF

Just lloked, it’s 104%

But that’s not what I mean, I am struggling to explain what I mean though so forget the over thrust thing.

Great topic! I was familiar with the climb concept and this works very good, but this decent method is new to me. I will try it on my next flight (or during my 777 test flight as soon as 20.1 is out). So far I used the GS/2 rule to determine my rate of decent. It also results in a rather low thrust setting, but only the heavy birds are getting close to 0% N1 that way (especially the MD11 which I fly quite a lot).

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Definitely try it. I used to usecthat method but when
I started doing this, I would never look back. It looks really odd at first being at cruise until so late but it works like a charm.

People play IF differently. I used to climb at 87% N1. These days I just set VS so that I climb at at most 90% N1.

As for descent speed, if you are planning 3 degree slope, then you should descend at 5 times your ground speed, not at an idle descent, or you will reach the ground too fast in a lot of aircraft.

Ok, why should we do that? Is there a limitation on how fast you can descend? What would that be. This was for people who are going for the upmost realism, if you don’t want that, that is absolutely fine. I have nothing against people who don’t mind being slight less realistic. But this is for those who do want realism.

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I read the entire post. I loved it and I agree fully. I’ve been using the climb technique using your pitch to maintain airspeed. Sometimes, I reach cruise in seven minutes; that’s okay.

I also use the 3 to 1 rule (take the 0’s off your cruising altitude, multiply by 3, add 10).

Good post today.

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No wayyy… I refuse to accept that lol. Is there someone whos a pilot IRL on the IFC who can confirm this? How broad is the term “routine?”

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The 3:1 rule and idle descend definitely don’t match, at least not in many IF aircraft.

While this is a very good idea in smaller aircraft to prevent overcontroling, my flight instructor told me that this is for GA aircraft only, and any attempt to do this in a commercial aircraft would result in extremely unwell passengers, and a possibly damaged aircraft.

Yeah, that’s why I said that.

“Sort of” is still partial, whereas I was saying, it is an absolute no in an airliner.

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