1. Once the parametric correction factors have been developed for every aircraft in the fleet of interest for the baseline set of operations, their validation can be pursued through variation of the fleet operations mix and assessment of the resulting aggregate fleet results for fuel burn and NOx calculated through application of the correction factors. The operational data for the aircraft in the fleet of interest from October 15, 2005 can be used as the baseline, and a sample distribution of flight distances for that day is provided in Figure 5. In order to quickly generate operational distributions for parametric correction factor evaluation, sample distributions were created as sums of three varying beta distributions. Examples of single beta distributions are given in Figure 6. The reasons that beta distributions were chosen to represent the distributions were that, as illustrated in Figure 6, they are finite, ending at a maximum specified range, and they are a function of two shape parameters Į and ȕ, which allows for easy parameterization and quick generation of multiple distributions. Figure 7 illustrates an example of a composite beta distribution made up of three single beta distributions with shape parameters as described in the figure, scaled to represent 1000 flights. The reason for using composite distributions is that they are able to generate more complex andmore realistic operations scenarios, e.g.forflightdistributionsthat may be bimodal.
2. Before this approach can be implemented, the target for the average replacement vehicle, representing the aggregate results of the fleet of interest, must be calculated from the AEDT output files of the fleet of interest along with a given operations mix. Equation (3) presents the calculation used for the aggregate fleet metrics. As previously described, AEDT generates fleet metrics for missions of varying flight distances and cruise altitudes. Each vehicle result for each of these missions, Yn,i,j, is multiplied by the number of flights for that particular mission's flight distance for the vehicle from the October 15, 2005 day, NFD,n,i, and the frequency of that particular mission's cruise altitude, fAlt,i,j,thedistributionofwhichisafunctionofthemissionflightdistance. Thisproductis calculated for each mission and then summed over the number of altitude combinations for each flight distance, the total numberof flightdistance for the aircraft,and all the aircraft in the fleet of interest.
3. The results of the application of the three approaches to developing a surrogate fleet to the 150-passenger seat class will be presented here. Table I contains the list of in-production airframes considered to be in the 150- passenger seat class for this study along with the ICAO engine codes for the engines associated with each of these airframes. This list was compiled by combining aircraft data from the 2006 Campbell Hill database with production status fromthe ICAO in-production database.