Ninth USA/Europe Air Traffic Management Research and Development Seminar (ATM2011)
Design of Aircraft Trajectories based on
Trade-offs between Emission Sources
BanavarSridhar and Neil Y. Chen Hok K. Ng
NASA Ames Research Center University of California
MoffettField, CA, USA Santa Cruz, CA, USA
FlorianLinke
DLR-GermanAerospace Center
Hamburg,Germany
http://www.aviationsystemsdivision.a...11_Sridhar.pdf
Abstract – Aviation operations affect theclimate in several
ways. Carbon dioxide, water vaporand other greenhouse
gasses are unavoidable by-productof the combustion of
fossil fuel. There are indications that persistent contrails
can lead to adverse climate change, although the complete
effect on climate forcing is stilluncertain. A flight
trajectory optimization algorithm with fuel and contrails
models, which develops alternativeflight paths, provides
policy makers the necessary datato make trade-offs
between persistent contrails mitigationand aircraft fuel
consumption. This study developsan algorithm that
calculates wind-optimaltrajectories for cruising aircraft
while reducing the amount of timespent in regions of
airspace prone to persistent contrails formation. The
optimal trajectories are developedby solving a non-linear
optimal control problem with path constraints. The
regions of airspace favorable topersistent contrails
formation are modeled as penaltyareas that aircraft
should avoid. The trade-offbetween persistent contrails
formation and additional fuel consumption is investigated
for 12 city-pairs in the continental United States. The
avoidance of contrails using only horizontal maneuvers
results in a small reduction of contrails with increasing
fuel consumption. When both horizontal maneuvers and
altitude are optimized, a 2% increase in total fuel
consumption can reduce the total travel times through
contrail regions by more than 70%. Allowing further
increase in fuel consumption does not seem to result in
proportionate reduction in contrail travel times. This
trend is maintained even in thepresence of uncertainties
in the contrail formation regionssuch as uncertainties in
relative humidity values computedby weather forecast
models.
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