# Is the distance to PNR (point of no return) affected by wind?

Is the distance to PNR (point of no return) affected by wind?

I did research it and found some links, but none discussed about the wind.

• How much research have you done? - A quick Internet search shows several useful sites. – Eugene Styer Jun 8 '18 at 14:10
• Related – Pondlife Jun 8 '18 at 14:20

Well, short answer: yes. Intuitively how could the wind not affect the PNR?

But, intuition, especially mine, is sometimes wrong, so let's see. I seem to remember this one from an algebra class, so I took a moment to figure it out. However, my aging brain was obviously going to take a more than a moment (my last algebra class was more than 50 years ago) thus, lazy soul that I am, I went to skybrary.aero and found:

Let's say we've got 2400 nm to fly in a 500 kt airplane facing a 100 kt headwind. Thus

D = 2400, H = 600, O = 400 and the PNR (ETP) = 1440 nm.

In a no wind situation the ETP (Equal Time Point) would obviously be 1200 nm, so wind does effect the the ETP.

In real life things are not so simple, and flight planning software will take care of calculating such things using winds aloft forecasts along the route of flight as well as other things.

• Thank you so much. Apparently my researching skills are not so good. – A_Fruitcake Jun 9 '18 at 16:49