USING FLIGHT MANUAL DATA TO DERIVE AERO-PROPULSIVE MODELS FOR
PREDICTING AIRCRAFT TRAJECTORIES

Chester Gong and William N. Chan


ABSTRACT

The Center/TRACON Automaton System (CTAS) is a set of air traffic management tools developed by NASA in
conjunction with the FAA. As part of its functionality, CTAS predicts aircraft flight trajectories using aeropropulsive
models and the kinetic equations of motion for various flight conditions including climbs. Precise aeropropulsive
models for all aircraft types are not yet available to NASA researchers. In an effort to improve climb
trajectory prediction of jet aircraft for which CTAS does not have a precise aero-propulsive model, a technique was
developed to derive an aero-propulsive model from readily available time-to-climb data found in flight manuals. A
case study was performed on a Boeing 737-400, for which time-to-climb data and aero-propulsive model data were
known. A new aero-propulsive model, identified by three aerodynamic and one propulsive parameter, was derived
from the time-to-climb data. The results showed it was possible to derive an aero-propulsive model for an aircraft
type that will allow CTAS to compute time-to-climb for a range of climb speeds that agree closely with known data.
This technique was then applied to a Learjet 60, an aircraft type for which a precise aero-propulsive model is not
available. A comparison of top-of-climb predictions made with a derived aero-propulsive model and actual top-ofclimb
from Learjet 60 radar track data reveal close agreement.