Navigation planning (Intro to D.S.T)

Continuing on from my last post (Climb & descent) you got your first taste of D.S.T and hear me talk about it heaps. So what is D.S.T? Distance / Speed = Time. A simple formula that will answer literally any en-route nav question you have!

  • How fast am I going?! ( DIST / TIME)

  • How much altitude do I need to lose?! (Vertical DIST / TIME) *last post’s formula

  • ECT…
    Now, I understand how confusing this is but here’s something that changes that!

  • Cover the item that you wish to find

    Say it was distance, you have 2 remaining letters below and a X ( multiplied by) symbol so what do you do? (Speed X Time) it’s as easy as that! - Now if you want to find the speed or time value it’s the opposite (D / T =S) or (D/S=T)

Before we get into some worked examples it is important to know that every time we X we must divide the end result by 60, and every time we / we must X the end result by 60 (unless finding TIME in HRS). I’ll show you what I mean.

Let’s say that we want to find out speed. The things we need to have are (DIST and TIME). So, we’ve traveled 59nm in 12 mins our speed is? 295kts. “But why did I get 4.91?!” That’s because you didn’t X by 60.

The best way that I can describe when to X or / by 60 is when it feels right. Like if your expecting a 3-number answer and get a 9 number long answer on the calculator then / by 60.

Ok, let’s try one more.
If Travelling at 175 kts, how long will it take to travel 245nm (in mins)? Ans: 84 mins

Remember, if you want hrs leave the 60 alone. This question however, is asking for mins.

One last thing that may help solidify your understanding is that You can change the “D” to anything you like.

  • Fuel
    Just change the speed understand the “S” as rate. I understand how difficult this can be to understand at first. I alone spent a solid week studying this till it clicked. I just hope that this helps you all out!

If I missed anything or have any questions, let me know✈️


Thanks for the help and clarification

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No problem!✈️

Skyvector lol

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Pfff Nah! I ain’t no child of the magenta line just yet!🤣

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