# ETOPS ETP Calculation

**URL:** <https://forum.navigraph.com/t/etops-etp-calculation/21673>\
**Category:** General\
**Created:** [December 5, 2025, 6:17am UTC](https://forum.navigraph.com/t/etops-etp-calculation/21673 "2025-12-05T06:17:18Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![xkoote](https://avatars.discourse-cdn.com/v4/letter/x/a4c791/32.png) [@xkoote](https://forum.navigraph.com/u/xkoote)\
**Post date:** [December 5, 2025, 6:17am UTC](https://forum.navigraph.com/t/etops-etp-calculation/21673/1 "2025-12-05T06:17:18Z")

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![SimBrief ETP](https://europe1.discourse-cdn.com/flex013/uploads/navigraph1/original/3X/3/4/34b07d6f1fd37e8299592b4ccd89b23a5b5ebd6c.jpeg)

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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**Author:** ![SimBrief](https://dub1.discourse-cdn.com/flex013/user_avatar/forum.navigraph.com/simbrief/32/4850_2.png) [@SimBrief](https://forum.navigraph.com/u/SimBrief)\
**Post date:** [December 5, 2025, 6:46pm UTC](https://forum.navigraph.com/t/etops-etp-calculation/21673/2 "2025-12-05T18:46:27Z")

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Hi, thanks for the report.

> [@xkoote](#):
>
> 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.

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](https://europe1.discourse-cdn.com/flex013/uploads/navigraph1/original/3X/c/3/c312025e9bdbe754f05b19e9b08ab8fa3095020d.png)

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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**Author:** ![xkoote](https://avatars.discourse-cdn.com/v4/letter/x/a4c791/32.png) [@xkoote](https://forum.navigraph.com/u/xkoote)\
**Post date:** [December 5, 2025, 9:16pm UTC](https://forum.navigraph.com/t/etops-etp-calculation/21673/3 "2025-12-05T21:16:18Z")

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You’re absolutely correct. And thanks for checking.

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**Author:** ![system](https://europe1.discourse-cdn.com/flex013/uploads/navigraph1/original/1X/4cc83e90d70ab312b1bd2d7527bddad309607265.png) [@system](https://forum.navigraph.com/u/system)\
**Post date:** [December 12, 2025, 9:16pm UTC](https://forum.navigraph.com/t/etops-etp-calculation/21673/4 "2025-12-12T21:16:47Z")

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