Dispatch landing distance

Hi, if you are expecting the 1.67 factor (dry runway) and 1.92 factor (wet runway), make sure to select the “Dispatch Method” calculation:

“Inflight Method” uses an entirely different methodology that isn’t based on fixed ratios.

Also note that the factored distance for wet runways is still calculated based on the dry runway actual landing distance, but with an increased factor (1.92 instead of 1.67).

So for example, here are 2 calculations for an A320 using MAX MAN braking, in dry and wet, using the Dispatch Method:

In the dry case, we see that factored / actual distance = 5,155 / 3,087 = 1.67.

In the wet case, (keeping in mind we need to base the factor on the dry actual distance from the first calculation): 5,928 / 3,087 = 1.92.

The “Actual Distance” that appears in the wet calculation, is basically the dry distance x 1.15. Which is how the regulations arrived at the 1.92 factor in the first place (1.92 = 1.67 x 1.15, or in other words, the factored distance on wet runways should equal the factored dry distance with an additional 15% increase).

Hope this helps,

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