Calculating ETPs for GA Aircraft – Part 1: Planning Tips

> | November 27, 2017 | 0 Comments
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Calculating ETPs for GA Aircraft – Part 1: Planning Tips
This business aviation blog post is the first of a two-part series on calculating ETPs for your flight.

There’s no regulatory requirement for general aviation (GA) operators to calculate Equal Time Points (ETPs) when planning and filing flight plans. However, ETP planning is a best practice procedure most operators choose to make as part of the pre-flight planning process.

The following is an overview of what you need to know:

1. ETP definition

An ETP is a geographical point in the flight where the aircraft would have the same flying time to continue on to a given airport or to turn back to another suitable airfield. While the ETP is generally close to midpoint of a flight leg this is dependent upon wind factor. If, for example, you’re flying from San Francisco (KSFO) to Honolulu (PHNL), the ETP would be the coast in/coast out point to PHNL or back to KSFO. If you’re flying into headwinds, however, the ETP will be closer to PHNL than to KSFO.

2. Purpose of ETPs

An ETP is used as a critical point based on an emergency situation. Such emergencies include depressurization, engine failure and/or in-flight medical emergency. Note that ETPs often vary, depending upon the particular emergency scenario and flight level you’ll need to descend to. For depressurization at cruise altitude the norm is to descend to 10,000 ft, engine failure often means descending to 25,000 ft. and in cases of medical emergency flight level changes when required, and will depend on the type of emergency. In practice, actual required changes in flight level will depend on the “operational specs” of the particular flight department.

3. Flight plan considerations

Not all flight plans contain ETPs as this is at the discretion of the individual operator. Most operators calculate ETPs when flying over large bodies of water or significant Arctic, Siberian or jungle regions. But, in some cases, operators choose to have ETPs when operating over smaller bodies of water and even land masses — such as the Gulf of Mexico or even Anchorage (PANC) to Houston (KHOU). To calculate or not to calculate ETPs always depends on a particular flight department’s ops specs. In general, it’s best practice to have ETPs on flight plans.

4. Weather considerations

There are weather recommendations and minima to consider when planning ETPs. Ideally the location should have at least a 500 ft. ceiling and one statute mile visibility to be considered viable. However, the case of limited ETP options the operator might consider a 200 ft. minimum ceiling and ½ statute mile visibility. You’ll also want to ensure there are no NOTAMs that could restrict operations to the ETP.

5. ETPs vs. ETOPs

ETPs differ from Extended Twin Engine Operations (ETOPs) points in that ETPs are not usually filed with flight plans while ETOPs points are. With an ETP you do not need to notify the particular airport or arrange service availability at the location, while you must do this with ETOPs points. Additionally, including ETOPs points in a flight plan may incur local airport changes whereas this is not the case with ETPs.

6. Filing ETPs

ETPs differ from Extended Twin Engine Operations (ETOPs) points in that ETPs are not usually filed with flight plans while ETOPs points are. With an ETP you do not need to notify the particular airport or arrange service availability at the location, while you must do this with ETOPs points. Additionally, including ETOPs points in a flight plan may incur local airport changes whereas this is not the case with ETPs.

Conclusion

ETP requirements will vary from one operator to another depending on the ops specs, crew preferences, weather conditions, and region of flight. ETPs are always recommended over regions such as large bodies of water and flying over landmass with few airport options. Note that unlike ETOPs, when filing a flight plan, ETPs won’t incur certain airport charges, so it’s a benefit for the flight to have additional options to consider.

Stay tuned for Part 2, which covers information special considerations regarding your ETPs.

Questions?

If you have any questions about this article or would like flight planning assistance for your next trip, contact me at nathanshelley@univ-wea.com.

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Senior Flight Planning Specialist Nathan Shelley is a well recognized subject matter expert on all flight planning aspects of operations to Africa, the Middle East and China. As a Flight Planner, Nathan supports some of Universal’s most active international clients. He’s also serves as a member of Universal’s Flight Planning Best Practices Group. Nathan has been twice nominated as Information Specialist and has been recognized with two Employee of the Month Awards. Nathan has 10 years in the aviation industry and received a degree in Aviation Management and Dispatch from San Jacinto College. He can be reached at nathanshelley@univ-wea.com.

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