Design of a flight planning system to reduce persistent contrail formation to reduce greenhouse effects

Abstract

During flight, aircraft emit greenhouse gases as well as water vapor and other byproducts. When water vapor combines with soot and other particulate matter, condensation trails (contrails) can form and persist in Ice Supersatured Regions (ISSR). Analysis of 45 days of varying atmospheric configurations showed that the location of ISSR can vary between Flight Level (FL) 267 to Flight Level 414, and are most prevalent in the summer months. This paper describes the design of a decision support system to assist in the flight planning of short, medium, and transcontinental routes to avoid the ISSR. The decision support system includes two independent input variables and five output dependent variables. Based on the length of the flight, and the amount of ISSR avoidance, the system can present a tradeoff analysis between (i) the miles of contrails formed, (ii) the amount of fuel consumed, (iii) the time spent in air, (iv) the distance traveled, and (v) the amount of CO2 produced. Results for a normal day's flight schedule for 45 days of ISSR configurations shows that the airline flight routes provide both warming and cooling radiative heating effects that are sensitive to the meteorological conditions and time of day (i.e. solar azimuth). Over the course of long flights, ISSR avoidance caused the aircraft to fly about two percent further; while contrail avoidance on short flights caused up to five percent or more increase in distance. Based on the analysis using the system, it is recommended that all flights over stage length of 1,000 nm be required to avoid ISSR because the radiative forcing due to contrails is tends to be greater than the radiative forcing caused by excess CO2 emissions to avoid contrail regions.