ETOPS ETP Calculation

SimBrief General
1

SimBrief ETP
SimBrief ETP1687×2160 469 KB

Hello,

with reference to the photo above, I am trying to understand SimBrief’s ETOPS calculation. In this sample you will notice that the most critical scenario is an all-engine decompression (as is usually the case) “DC”. Which I assume it is what it stands for.

Meaning, the winds to determine the ETP should be taken at FL100. If I look at the wind components used to determine this ETP of P026 and M037, it seems the wind component at cruise level is assumed and not the one at FL100. Looking at the winds aloft chart at FL100, there is no point over the ocean where even total wind speed reaches 26 knots. Let alone a component.

Could it be that the scenario uses cruise winds for a FL100 (DC) ETP calculation, or am I looking at it the wrong way?

Thanks,

Xander

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Hi, thanks for the report.

It should be noted that you can’t really look at the vertical profile for this. The winds along the ETOPS diversion legs might be different than the ones along your planned route. As you can see in the map screenshot below, the winds are a bit stronger towards the north of your route:

image
image1338×1045 284 KB

That being said, I did find a small issue in the ETOPS wind averaging code. It should improve the accuracy of the components in the future.

Best regards,

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You’re absolutely correct. And thanks for checking.

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