Cruise Altitude and Speed Optimization

Project Number: 015  COMPLETE
Category: Operations

The purpose of this project is to examine the potential fuel burn benefits of altitude and speed optimization in the cruise phase of flight. Airlines may be able to achieve cost reductions and mitigate environmental impact by making small modifications to the cruise phase operating procedures. In this study, an analysis framework was developed to evaluate the relative fuel efficiency of baseline and optimized cruise flight profiles from historical operations.

The fuel efficiency of an aircraft at any point along its flight path is a function of weight, altitude, speed, wind, temperature, and other second-order effects. At a fixed weight, there exists a combination of speed and altitude at which instantaneous fuel efficiency is maximized.

For a full flight, this becomes an optimal sequence of speeds and altitudes to minimize fuel consumption. The speed and altitude at which aircraft are actually flown may differ from this optimal point for a variety of operational and practical reasons. Integrated fuel consumption depends on effective trajectory planning in speed and altitude as well as in lateral flight path. For this project, different optimal profiles in altitude, speed, and joint altitude/speed combinations are examined for potential operational application.

Ultimately, the objective of ASCENT Project 15 is to identify flights with large potential cruise efficiency improvement. The technologies and procedures required to realize improvements in these operations will be examined in coordination with airlines, air traffic controllers, and regulators.

Last Updated 3/31/2020

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