ECONOMIC GROWTH, DEMAND, AND ENERGY USE
On a per capita basis, rising demand for mobility is well correlated with growth in gross domestic product (GDP)—a measure of national economic activity—across a wide variety of economic, social, and geographic settings. One reason for this may be found in the roughly constant shares of income and time people dedicate to transportation. A fixed budget for travel leads to an increase in total travel demand per capita (e. g., RPK per capita) in approximate proportion to income. In addition, a person spends an average of 1.0-1.5 hours/day traveling. One key implication of such invariance is that as demand for movement increases, travelers tend to shift toward faster modes of transportation. Consequently, continuing growth in world population and income levels can be expected to lead to further demand for air travel, both in terms of market share and RPKs. As a result, high-speed transportation, in which aviation is anticipated to be the primary provider, will play an increasingly important role and may account for slightly more than one-third of world passenger traffic volume within the next 50 years. In general, among industry and government predictions, growth in passenger air transportation has been typically projected to be between 3 and 6%/year as an average over future periods of 10-50 years.
Aviation fuel consumption today corresponds to 2-3% of the total fossil fuel use worldwide, more than 80% of which is used by civil aviation operation. Energy use in the production of aircraft is relatively minor in comparison to that consumed in their operation. Although the majority of air transportation demand is supplied by large commercial aircraft, defined as those aircraft with a seating capacity of 100 or more, smaller regional aircraft have emerged as an important component of both demand and energy use within air transportation. For example, in the United States, although regional aircraft currently perform under 4% of domestic RPKs, they account for almost 7% of jet fuel use and for 40-50% of total departures. Future growth in demand for regional aircraft RPKs could be up to double the rate for large commercial aircraft. Cargo operations account for some 10% of total revenue ton-kilometers and fuel use within the aviation sector. Economic activity, as measured by world GDP, is the primary driver for the air cargo industry growth. World air cargo traffic is expected to grow at an average annual rate of over 6% for the next decade.