VNAV: What is it and why is it important? [Vnav basics and how the Airliners descend!]

This video is about VNAV or Vertical Navigation.

When flying in a small aircraft at low altitudes is easy to know when to start the descend for the landing.

However, when operating in an Airliner into busy airspace the calculation of the Top of Descend becomes more complicated.

This is so because, in busy Airspaces, such as Madrid for example, you have in your Standard Arrival multiply altitude and speed restrictions.

So, you can imagine that to calculate your top of descend correctly and fly a continuous descend to the next restriction is not an easy task.

And what happens if you have more tailwind or your aircraft is heavier, or you need to use the Anti ice, etc?? Your descend path will be different compared to an ideal world descend without all these variables.

Here is when the VNAV plays its rule. The Vertical Navigations takes into account all these variables and provides you with an accurate Top of descend.

In order to have a correct VNAV path descend you need to insert the data into the FMS accurately, otherwise, the VNAV will make some mistakes.

The Vertical Navigation calculates the descend path going backward from the runway.

It starts from the runway or the missed approach point and calculates a constant 3 degrees from the last restriction, then it will give you a segment for your declaration, a segment for every altitude restrictions, then it takes into account the weather, the weight and any other factor the may affect your descend.

And in the end, it will give you a correct Top of Descend.

Comparing an ideal world descend (without external factors, deceleration and altitude restrictions) with a real descend you will notice that the Top of descend position will change substantially.

If you want to know more about the Standard Arrival watch the YouTube video below:

If you want to know more about IFR watch the video below:

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Disclaimer:
THIS VIDEO IS FOR ENTERTAINMENT PURPOSES ONLY.
NOT FOR REAL-LIFE OPERATIONS.
PLEASE REFER TO THE OFFICIAL MANUAL AND DOCUMENTATION.
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[brendanbeamish]

Yes, please. An indepth look at VNAV / RNAV with practical demonstration on the simulator will be most helpful to better understanding. There are many variables to these, it can be quite tough to grasp with just reading the ATPL theory.

[BrunoMCDowell]

Man, you are AMAZING. I'm so glad I came across this video. PERFECT!

[solids]

Its not a question but I want to thank you for all the videos, im preparing myself for an airline interview, its going to be tomorrow!!! thank you for all the teachings!

[lucatraversa]

Excellent video, as the other ones on your channel. I remembered that the "thumb rule" of "multiply by three" had to be applied to the difference between your flight level and the airport elevation (we could have a 2.000 ft airport elevation, for istance). Anyway, in real world, it is a small difference for a rule that is "approximated" for definition.

[ghostrider-beek]

excellent! 1000 views will turn to 10, 000, to 100, 000

[bennithomas]

Excellent video Captain, I need to know more about VNAV, I expect more videos on this, I am planning to begin my flight training in Germany, So it will be great help to know more about this ! Thanking you once again .

[sohankantimahanthi]

Excellent video.Could you also explain lnav, rnav, waas.

[MrEthanhines]

Yes please do and please tell me if the AP can fly a RNAV approach without manual input or do I have to disconnect the AP and follow the pink boxes.

[EpicDBZking]

Thanks man this helped me fly and understand planes better in flight simulator 2020

[raccoonair]

Excellent explanation how to work the VNAV backwards from the runway to the T/D… thanks.

[mba]

Thank you Captain! Please can you make a VNAV video for climb as well as descent using the VNAV descent VTK prompt and when it is best to follow and best to abandon VNAV such as when ATC takes over your descent profile.Also it would be nice to demo a GPS Approach and differentiate between RNAV and RNP Approaches particularly showing LNAV/VNAV and LPV(if 737 is certified for LPV) minimums.

[PILOTCLIMB]

Ask me any questions in the comments below!! I will help you out!! Happy Landings.

[CMQOE-Tutorials-wmkc]

Wonderful explanation
Plz make a sim vdo about vnav and Lnav....thks

[choudharyofficals]

Sir I am bihar india, my eng is weak although I understand your concept in nice way, thank u sir ❤️

[vimalvenky]

please make video on more vnav details and auto npilot also.. love watching your channel

[MyLisboa]

HI Captain...Thank you so much and just a little silly question ...does the VNav and LNav also apply for B777 ...?

[yashashreebhargude]

Yes please do give us sim and more details of VNAv

[azizunsalkaraman]

Hello captain, first of all thanks for these videos. I have a question about Vnav and engine out situation. I know we can engage auto pilot if we takeoff with vnav armed on ground. But my question is what about takeoff without arming vnav on ground. Can we engage vnav at 400 ft and then engaging autopilot if we experience engine failure at v1?

[alessio]

Il sentiero verticale VNAV fu creato per adattare allo STAR.

[TubeMart]

What height is selected for VNAV? And at which point/fix exactly?