Air travel times and the reliability of expected travel times are important determinants of customers' satisfaction, air system operating efficiency, and policymakers' success in meeting performance objectives. A major reason consumers choose to travel by air is that it is often the fastest way to travel long distances.
The Air Travel Time Index (ATTI) rose by 0.5 percent per year between 1990 and 2000 and then fell by 0.7 percent per year between 2000 and 2004 (figure 5-8). The ATTI measures average flight times of nonstop flights using the time elapsed between the scheduled departure and actual arrival, while controlling for different flight characteristics such as distance. In comparison, an index of the average scheduled travel time for nonstop flights in the United States rose by 0.2 percent per year between 1990 and 2000 and remained relatively unchanged between 2000 and 2004. The gap between the two measures widened from 8 minutes in 1990 to a maximum of 11 minutes in 2000 and then narrowed to 7 minutes in 2004.
The Air Travel Time Variability Index (ATTVI) rose by an average of 4 percent per year between 1990 and 2000 and then fell by 3 percent per year between 2000 and 2004 (figure 5-9). The ATTVI measures the variability of flight times of nonstop flights based on differences between travel times on individual flights and the average travel times for the same flight. Thus, not only did the travel time for a typical flight take longer between 1990 and 2000, but it also became more uncertain. However, between 2000 and 2004, both flight travel times and their variability improved despite an increase in the number of flight operations.1
The Bureau of Transportation Statistics (BTS) research developing the ATTI and ATTVI is intended to improve the measurement of air travel time and reliability. Using data BTS collects from airlines (box 5-B), the ATTI enables analysis of changes in air travel time nationally, as well as by airport, carrier, time of day, and flight distance. For instance, from 1990 to 2004, most improvements occurred in flights departing in the evening offpeak (after 9:00 p.m.). The least improved were flights departing in the evening peak (between 3:00 p.m. and 9:00 p.m.). Grouped by distance, flights of more than 1,000 miles were approximately unchanged, while travel times of flights of 500 miles or less increased.
1 Improvement occurs when the ATTI and ATTVI decrease.