From August to September 2017, enplanements on domestic flights declined 3.0 percent while international enplanements to and from the U.S. fell 3.8 percent, resulting in a 3.1 percent systemwide decline (Tables 1, 2, 3).

In one year, from September 2016 September 2017, enplanements on domestic flights declined 1.65 percent while enplanements on U.S. airlines’ international flights to and from the U.S. fell 0.4 percent, resulting in a 1.4 percent systemwide decline (Tables 1, 2, 3).

In three years, from September 2014 to September 2017, enplanements on domestic flights increased 8.0 percent while international enplanements rose 4.34 percent, resulting in a 7.5 percent systemwide increase (Tables 1, 2, 3).

Unadjusted systemwide, domestic and international enplanements were below the all-time highs for the month of September (Tables 13, 14, 15).

Trends (Percent changes based on unrounded numbers)

Seasonally-adjusted

Systemwide passenger enplanements (68.6 million) were down 3.8 percent from the all-time seasonally-adjusted high (71.4 million) reached in July 2017 (Table 1). Domestic passenger enplanements (60.0 million) were down 3.7 percent from the all-time seasonally-adjusted high (62.3 million) reached in July 2017 (Table 2). International passenger enplanements (8.6 million) were down 5.2 percent from the all-time seasonally-adjusted high (9.1 million) reached in April 2017 (Table 3). 

Systemwide revenue passenger miles (RPMs) (78.4 billion) were down 3.4 percent from the all-time seasonally-adjusted high (81.12 billion) reached in July 2017 (Table 4). Domestic RPMs (55.4 billion) were down 3.9 percent from the all-time seasonally-adjusted high (57.7 billion) reached in July 2017 (Table 5). International RPMs (23.0 billion) were down 3.3 percent from the all-time seasonally-adjusted high (23.7 billion) reached in April 2017 (Table 6).

Systemwide available seat-miles (ASMs) (95.1 billion) were down 2.0 percent from the all-time seasonally-adjusted high (97.0 billion) reached in July 2017 (Table 7). Domestic ASMs (66.45 billion) were down 2.5 percent from the all-time seasonally-adjusted high (68.2 billion) reached in August 2017 (Table 8). International ASMs (28.7 billion) were down 1.3 percent from the all-time seasonally-adjusted high (29.0 billion) reached in June 2017 (Table 9).

Systemwide load factor (82.4) was down 2.4 points from the all-time seasonally-adjusted high (84.8) reached in October 2015 (Table 10). Domestic load factor (83.4) was down 2.6 points from the all-time seasonally-adjusted high (86.0) reached in October 2015 (Table 11). International load factor (80.1) was down 2.9 points from the all-time seasonally-adjusted high (83.0) reached in March 2013 (Table 12).

Load factor is a measure of the use of aircraft capacity that compares the system use, measured in RPMs as a proportion of system capacity, measured ASMs.

The seasonally-adjusted load factor fell from August (83.2) to September (82.4) because system capacity fell (2.0 percent decline in ASMs) less than passenger travel (2.9 percent decline in RPMs) (Tables 4, 7).

Seasonally adjusted trends are for the time period January 2000 to present. Additional data, including domestic and international numbers, can be found on the seasonally-adjusted data  page.

Unadjusted

Systemwide passenger enplanements (64.9 million) were down 2.4 percent from the all-time September high (66.5 million) reached in 2016 (Table 13). Domestic passenger enplanements (57.1 million) were down 2.6 percent from the all-time September high (58.6 million) reached in 2016 (Table 14). International passenger enplanements (7.8 million) were down 1.1 percent from the all-time September high (7.9 million) reached in 2016 (Table 15).

Systemwide RPMs (74.6 billion) were down 0.9 percent from the all-time September high (75.3 billion) reached in 2016 (Table 16). Domestic RPMs (51.9 billion) were down 1.5 percent from the all-time September high (52.7 billion) reached in 2016 (Table 17). International RPMs (22.8 billion) reached an all-time September high, up 0.5 percent from the previous high (22.7 billion) reached in 2016 (Table 18).

Systemwide ASMs (91.4 billion) reached an all-time September high, up 1.1 percent from the previous high (90.45 billion) reached in 2016 (Table 19). Domestic ASMs (63.1 billion) reached an all-time September high, up 1.0 percent from the previous high (62.5 billion) reached in 2016 (Table 20). International ASMs (28.3 billion) reached an all-time September high, up 1.3 percent from the previous high (27.9 billion) reached in 2016 (Table 21).

Systemwide load factor (81.6) was down 1.6 points from the all-time September high (83.3) reached in 2016 (Table 22). Domestic load factor (82.2) was down 2.1 points from the all-time September high (84.23) reached in 2016 (Table 23). International load factor (80.5) was down 3.1 points from the all-time September high (83.6) reached in 2010 (Table 24).

The unadjusted load factor fell from September 2016 (83.3) to September 2017 (81.6) because system capacity rose (1.1 percent increase in ASMs) while passenger travel declined (0.9 percent decrease in RPMs) (Tables 16, 19).         

Unadjusted trends are for the time period January 1996 to present. Data are available at Customize Table and can be downloaded from the seasonally-adjusted data  page.

Explanation of seasonal adjustment

When the primary purpose is to examine monthly shifts in transportation services output and analyze short-term trends, the variation introduced by normal seasonal changes must be removed from the data. Transportation is highly seasonal, and without adjustment, the data do not give an accurate picture of underlying changes in aviation, passenger travel.

Seasonal adjustment of the data removes the seasonal events that follow a regular seasonal pattern. Changes that are not due to seasonality, such as a change in air travel resulting from economic conditions become more readily apparent.

The aviation data are seasonally adjusted for the effects of trading day, moving holidays, and data outliers.

See Seasonal Adjustment for methodology and additional explanation.

Reporting Notes

Data are compiled from monthly reports filed with BTS by commercial U.S. air carriers detailing operations, passenger traffic and freight traffic. This release includes data received by BTS from 83 carriers as of Dec. 5 for U.S. carrier scheduled civilian operations.

Go to http://www.transtats.bts.gov/releaseinfo.asp for the complete list of reporting and non-reporting carriers. U.S. carriers’ foreign point-to-point flights are included in system and international totals. To create a customized table for passengers, flights, RPMs, ASMs and other data, including non-scheduled service, go to https://www.transtats.bts.gov/TRAFFIC/

For additional scheduled service numbers for U.S. and foreign airlines, by airline and by airport, see Passengers, Flights, Revenue Passenger-Miles, Available Seat-Miles and Load Factor.

Traffic numbers are available on the BTS website at TranStats, the Intermodal Transportation Database, at http://transtats.bts.gov.  Click on “Aviation.”  For systemwide passengers, RPMs and ASMs by carrier through September, click on “Air Carrier Summary Data (Form 41 and 298C Summary Data),” and then click on “Schedule T-1.” Use crosstabs to find scheduled service.

For domestic numbers through September and international numbers through June by origin as well as by carrier, click on “Aviation,” then click on “Air Carrier Statistics (Form 41 Traffic).”  Click on “T-100 Market” for system passenger numbers, “T-100 Domestic Market” for domestic or “T-100 International Market” for international.  For flights, stage length and trip length, use the appropriate T-100 Segment database. Use crosstabs to find scheduled service.

International totals in this press release consist of all U.S. carrier operations to and from the U.S. and from one foreign point to another foreign point. TranStats T-100 systemwide and international totals do not include U.S. carriers’ foreign point-to-point flights. For September, U.S. carriers reported 45,771 foreign point-to-point passengers. For January through September, U.S. carriers reported 504,230 foreign point-to-point passengers.

Data are subject to revision. BTS has scheduled Jan. 12 for the release of October traffic data. None of the data are from samples so measures of statistical significance do not apply.

Seasonally-Adjusted Tables

Passenger Enplanements on U.S. Airlines, Seasonally-Adjusted (Tables 1-3)

Revenue Passenger-Miles on U.S. Airlines, Seasonally-Adjusted (Tables 4-6)

Available Seat-Miles on U.S. Airlines, Seasonally-Adjusted (Tables 7-9)

Load Factor on U.S. Airlines, Seasonally-Adjusted (Tables 10-12)

Unadjusted Tables

Passenger Enplanements on U.S. Airlines, Unadjusted (Tables 13-15)

Revenue Passenger-Miles on U.S. Airlines, Unadjusted (Tables 16-18)

Available Seat-Miles on U.S. Airlines, Unadjusted (Tables 19-21)

Load Factor on U.S. Airlines, Unadjusted (Tables 22-24)