CHAPTER II AIRPORT OPERATIONS FORECASTS For a variety of reasons, the numbers of potential air passengers, tons of air cargo and private airplanes are not direct indicators of how much airport capacity is needed. The reasons are explained below in the course of translating the forecast volumes of passengers, cargo and private planes into airport operations. Commercial Passengers Of the potential commercial air passengers forecast for the future, some may be diverted to other means of travel, some may take seats now vacant on presently scheduled flights, and some may be accommodated on the larger planes expected to be put into service on present routes. Thus, the number of new flights is not expected to grow as fast as the number of passengers. These trends are summarized below. Diverted Passengers. In the future, some portion of potential air passengers may be diverted from regular commercial flights by alternative means of travel, such as vertical or short take-off and landing (V/STOL) aircraft-which may operate from special downtown sites-and new high speed trains. Both of these new competing modes of travel require further technological development before they will be economical and fast enough to divert significant numbers of passengers from the regular commercial planes. However, such developments seem very likely to occur by 1980. If both V/STOL aircraft and high speed trains are providing a reasonable level of service by then, nearly three and one-half million passengers per year could be diverted from the regular airplanes. As shown in Figure 4, the number of passengers diverted annually could grow to nearly seven million by 1985 and more than eleven million by 1990. Such diversions would range close to ten percent of the total potential commercial air passengers. FIGURE 4. COMMERCIAL AIRPLANE PASSENGERS DIVERTED WASHINGTON-BALTIMORE REGION: 1980-1990 27-254 O 70 pt. 1---9 Growth of Commercial Flights. The most important factors influencing the number of flights needed to accommodate future commercial air passengers are (1) average aircraft size, and (2) the number of passengers on each flight. The average aircraft size-based on the national trend-is expected to increase markedly in the next few years. For example, the Boeing 747, to be introduced late in 1969, will have 350 to 400 seats; advanced three-jet airplanes with 250 seats are being planned for introduction around 1971; and the U.S. supersonic transport (SST) will seat approximately 350 passengers. The average aircraft sizes projected for the three commercial airports in the Washington-Baltimore Region are shown in Figure 5. It should be noted that the aircraft using Washington National Airport will be considerably smaller on the average than those using Dulles International and Friendship International Airports. This is because of its close-in location and the restrictions placed upon four-engine aircraft. FIGURE 5. AVERAGE AIRCRAFT SIZE AT COMMERCIAL AIRPORTS Even assuming that substantially higher percentages of their seats will be filled (see Figure 6), the smaller planes at Washington National could not be expected to continue accommodating as many passengers per flight as the larger airplanes at Dulles and Friendship (see Figure 7). By 1985, Washington National would begin to fall considerably behind the other two airports in the number of passengers accommodated on each flight. Because of differences among the three major commercial airports-which create differences in the sizes of aircraft used-estimates of the total number of commercial passenger flights, needed to accommodate the forecast number of passengers, must be based upon assumptions about the operation of the three airports. Three different sets of assumptions-and three different estimates-have been made. The three sets of assumptions are as follows. Case I: Case II: Case III: All three airports were assumed to be operating and to be expandable in an unrestricted manner. Washington National Airport was assumed to be closed, while the other two airports were assumed to be operating and to be expandable in an unrestricted manner. All three airports were assumed to be operating; however, operations and traffic volumes were assumed to be restricted at Washington National Airport, while the other two airports were assumed to be unrestricted in their operations and to be expandable in an unrestricted manner. Figure 8 shows the total number of commercial passenger flights forecast for the Washington-Baltimore Region in each case from 1970 to 1990. It can be seen from FIGURE 8. FORECAST NUMBER OF COMMERCIAL PASSENGER FLIGHTS WASHINGTON-BALTIMORE REGION: 1970-1990 |