ETOPS location determination is insensitive to winds

Hello,
I noticed an issue with the dispatch calculations for ENTRY, ETP, and EXIT locations. Currently the system chooses a location on the edge of each 60 minute ring and calls that the ENTRY or EXIT point as appropriate and at the midpoint of the overlapping ETOPS range rings determines that to be the ETP and applies necessary fuel to meet the wind requirements. This can not be the ETP with wind, this only applies in a no wind situation.

Per AC 135-42, address to On-Demand 135 air carriers, although the same requirement applies to part 121 scheduled air carriers, https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_135-42.pdf
Chapter 2, Section 203, paragraph b:

However, once a certificate holder determines from their route planning that the
ETOPS requirements apply, all [emphasis added] subsequent flight planning in the ETOPS area of operation must
account for the affects of wind and temperature on the calculated distances from each ETOPS
alternate airport.

The ETOPS rings are computed with no wind which is appropriate, but when it comes to ETOPS ENTRY, ETP, and EXIT points, the position of those points must take into account wind. I ran a CYUL - EGPF 207 minute ETOPS Direct flight with 1 waypoint at: 561105N0420702W. Using the CL650 airframe
The average wind component was 66 knots. in both the wind and no wind flight plan the ETP position was identical. This is incorrect and should be addressed.

In summary, currently the system chooses ETOPS positions based on the no wind constraints and applies fuel to meet fuel requirements, this isn’t in accordance with required ETOPS planning rules and should be updated to reflect the same.

1 Like

Hi, thanks for the report. This bug only affected certain airframes, but it has been fixed now.

To clarify, the positions of the ENTRY and EXIT points are always determined using 60 minutes flying time at the approved one-engine-inoperative cruise speed, under standard conditions in still air. So these won’t change, regardless of wind.

The critical fuel calculations (from the ENTRY to first ETOPS suitable airport, from the EXIT to final ETOPS suitable airport, and from each ETP to its associated suitable airports) should account for the winds of course.

Let me know if you find any other issues.

Best regards,

Thank you for the rapid response and update! It’s very nice to see it working properly now. Have a great rest of your day!

One other slight issue, we were going over some ETOPS plans in with the CL650 specifically and noticed the ETOPS TAS computed was ~422 knots in a DX scenario which is much faster than the One Engine Inoperative speed we have in the documentation. Is there any additional information we can provide to you need regarding single engine cruise that might be helpful in refining this value further?

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