---
title: Enroute Driftdown Analysis
description: ASAP STAR driftdown analysis
image: https://insights.asapinc.net/hubfs/Logos/ASAP%20STAR%20for%20iPad%20Pic%203%20(IG%20Size).png
---

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# Enroute Driftdown Analysis

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Enroute Drift-Down Analysis

ASAP STAR offers many industry-leading tools and capabilities, such as specialized drift-down en route analysis to max payload! Our en-route performance covers obstacles between the takeoff and landing segments of flight in the event of an engine failure. The loss of an engine at cruise causes the aircraft to drift down to the single-engine service ceiling, our calculations model this service ceiling and ensure the aircraft will clear the obstacles by the required margin. 

 

Method 1: We plot the aircraft trajectory using the optimal route calculations provided by flight planning organizations. We also calculate the fuel burn for approximate aircraft weight loss across the flight path. Obstacles are identified, and their distances are calculated from the reference location. The analysis can be computed using either actual or forecasted atmospheric conditions. Based on temperature, pressure, obstacle height, and safety margins, we can calculate the maximum weight for obstacle clearance. This provides the en route performance calculations necessary for flights over mountainous terrain.

Method 2: This is an extension of method one if limiting obstacles are encountered on a route that does not allow continued flight.  If the failure occurs before that point, you must return to the departure or alternate airport. If the failure occurs after that point, you may proceed to the destination airport. Using the point of no return negates the need for a takeoff weight penalty as in method one.

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### [Optional Features now available in ASAP STAR](https://insights.asapinc.net/feature-highlights/optional-features-now-available-in-asap-star)

##### **Below is a continued list of available features in ASAP STAR. Some feature previews may link to a dedicated page with more information, screenshots, or videos. Please...**

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### [New Feature: Additional Alternates](https://insights.asapinc.net/feature-highlights/new-feature-additional-alternates)

Per Part FAR Part 121, a flight could require a takeoff alternate and a second destination alternate in addition to our current alternate capability. You can now add...

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[Read More](https://insights.asapinc.net/feature-highlights/new-feature-additional-alternates)

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- Runway Analysis
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