Quick way to calculate ROD

[400guy2]

Originally Posted by Noknoipobin

Additional note on calculating ROD/ROC

(More precisely, 3° ≈ 318 ft/NM → GS × 5.3)

I think you mean 5.03. No?

[Noknoipobin]

Originally Posted by 400guy2

I think you mean 5.03. No?

Thank you ,I mean it’s actually 5.3, not 5.03.

tan 3° = height / distance
0.0524 = X / 6076 (1 NM)
→ X = 6076 × 0.0524 ≈ 318.4 ft

So, over 1 NM the height is about 318 ft.

Make 1 NM = 1 minute then→ GS = 60 kt
if flying 60 kt → ROD ≈ 318 ft/min
If flying at Y kt: ROD = (318 / 60) × Y ≈ Y × 5.3

When we truly understand the actual values, it helps improve our situational awareness and caution.
In real operations, it may be difficult to fly exactly at an ROD of 530 (GS × 5.3)(in V/S mode). However, if we are flying at around 500 (GS × 5), we can still anticipate how the aircraft profile will develop. This helps avoid confusion or surprise about why, even with a “correct” ROD (GSx5), the aircraft may appear high.

Try looking at an example AIP chart for EGLL.

[oceancrosser]

Wondering how I ever got through a 43 year pilot career without these formulae ringing in my head…

[400guy2]

Originally Posted by Noknoipobin

Thank you ,I mean it’s actually 5.3, not 5.03.

Right you are. I am embarrassed at my slip and at my gall in offering a correction.

[Neutral Selector]

Originally Posted by oceancrosser

Wondering how I ever got through a 43 year pilot career without these formulae ringing in my head…

I was just thinking the same thing. People seem to be making an easy job, very hard!

[Noknoipobin]

I understand your sarcasm. I’m simply explaining this for those who wonder if what I wrote is right or wrong, providing a clear source and reference so it’s not just guesswork. Besides, this isn't difficult at all—it’s just middle school or even upper elementary math. The entrance exams to become a pilot were far harder than this. I’ve been flying for over 30 years and have seen many pilots who still can't operate an FMS and have to rely on their co-pilots, or those who can barely read a chart—yet they’ve all managed to survive or reach retirement.

[Noknoipobin]

Originally Posted by 400guy2

Right you are. I am embarrassed at my slip and at my gall in offering a correction.

I’m sorry for making you feel that way. I was only trying to explain and share a bit more about how I work,so that it’s credible and accurate.Sometimes I may speak too much.

[400guy2]

Originally Posted by Noknoipobin

I’m sorry for making you feel that way. I was only trying to explain and share a bit more about how I work,so that it’s credible and accurate.Sometimes I may speak too much.

Not at all. I appreciate your explanation. My mistakes are entirely my own fault.

[bill fly]

Originally Posted by oceancrosser

Wondering how I ever got through a 43 year pilot career without these formulae ringing in my head…

Well, of course you can get in from a sub optimal approach at the cost of fuel but its nicer to hit it on the button. I was grateful for that tip from my chief and have used it on countless occasions.

Apart from approaches, in the crowded airspace of today you often get asked if you can make a given height (climbing or descending) by a given point or distance.
Then its nice to have a handy tool to give a quick answer.

Handy being the operative word though. As a slower learner I have always appreciated the simple solution and I agree that some of the examples look anything but at first sight.