A Note on the "45 Degree Rule"

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The "45 degree rule" refers to the idea of watching the previous group and waiting until they have fallen far enough behind the airplane. It is a poor name because the previous group never actually gets to 45 degrees, and because it seems to focus on some angle when the idea is to get horizontal separation.

In the context of the air speed vs ground speed debate it is the classic air speed technique.

It also only works in zero to very low upper winds. See Dealing with Uppers for a discussion of this.

Some of my exit separation articles were written in the context of people being told to look at the green light, count some mysterious number of seconds, and go. I was trying to get people to look out the door at the situation they were about to jump into and the "45 degree rule" seemed like progress.

I'm hoping that the idea of putting a ground speed vs seconds table back by the door will catch on and we can move on.

OPEC started changing the oil prices in 1973 and multiple groups per pass became common shortly after that. You'd think after almost 30 years we'd be further along than just "leave more time" in strong uppers.

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