The U.S. Department of Transportation’s Bureau of Transportation Statistics (BTS) reported today that U.S. airlines’ systemwide (domestic and international) scheduled service load factor – a measure of the use of airline capacity – rose to 83.6 percent in September, seasonally adjusted, rising after two months of decline from July through August (Table 1).

The seasonally-adjusted load factor rose from August (82.6 percent) to September (83.6 percent) because passenger travel grew (1.2 percent increase in Revenue-Passenger-Miles (RPMs)) while system capacity (Available Seat-Miles (ASMs)) was virtually unchanged (Tables 4, 7).

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 in ASMs.

Trends:

Seasonally-adjusted

Systemwide load factor (83.6 percent) was down 1 point from the all-time seasonally-adjusted high (84.6 percent) reached in October 2015 (Table 1). Domestic load factor (84.8 percent) was down 1.1 points from the all-time seasonally-adjusted high (85.9 percent) reached in October 2015 (Table 2). International load factor (80.6 percent) was down 2.5 points from the all-time seasonally-adjusted high (83.1 percent) reached in March 2013 (Table 3).

Systemwide RPMs (78.3 billion) were virtually equal to the all-time seasonally-adjusted high (78.3 billion) reached in June 2016 (Table 4). Domestic RPM (55.5 billion) reached a new seasonally-adjusted all-time high, up 0.5 percent from June 2016 (Table 5). International RPMs (22.8 billion) were down 1.2 percent from the all-time seasonally-adjusted high (23.1 billion) reached in June 2016 (Table 6).

Systemwide ASMs (93.8 billion) reached a new seasonally-adjusted all-time high, up slightly from August 2016 (93.7 billion) (Table 7). Domestic ASMs (65.5 billion) reached a new seasonally-adjusted all-time high, up 0.1 percent from August 2016 (65.4 billion) (Table 8). International ASMs (28.3 billion) were down 0.5 percent from the all-time seasonally-adjusted high (28.4 billion) reached in June 2016 (Table 9).

Systemwide passenger enplanements (69.3 million) reached a new seasonally-adjusted all-time high, up 0.3 percent from June 2016 (69.0 million) (Table 10). Domestic passenger enplanements (60.6 million) reached a new seasonally-adjusted all-time high, up 0.5 percent from May 2016 (60.3 million) (Table 11). International passenger enplanements (8.6 million) were down 1.4 percent from the all-time seasonally-adjusted high (8.8 million) reached in June 2016 (Table 12).

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 load factor (83.3 percent) was up 0.3 points from the all-time September high (83.0 percent) reached in 2015 (Table 13). Domestic load factor (84.2 percent) was up 0.4 points from the previous all-time September high (83.8 percent) reached in 2015 (Table 14). International load factor (81.1 percent) was down 2.5 points from the all-time September high (83.6 percent) reached in 2010 (Table 15).

Systemwide RPMs (75.3 billion) reached an all-time September high, up 3.9 percent from the previous high (72.5 billion) reached in 2015 (Table 16). Domestic RPMs (52.7 billion) reached an all-time September high, up 5.6 percent from the previous high (49.9 billion) reached in 2015 (Table 17). International RPMs (22.7 billion) reached an all-time September high, up 0.2 percent from the previous high (22.6 billion) reached in 2015 (Table 18).

Systemwide ASMs (90.4 billion) reached an all-time September high, up 3.6 percent from the previous high (87.3 billion) reached in 2015 (Table 19). Domestic ASMs (62.5 billion) reached an all-time September high, up 4.5 percent from the previous high (59.8 billion) reached in 2007 (Table 20). International ASMs (27.9 billion) reached an all-time September high, up 0.5 percent from the previous high (27.8 billion) reached in 2015 (Table 21).

Systemwide passenger enplanements (66.5 million) reached an all-time September high, up 4.3 percent from the previous high (63.7 million) reached in 2015 (Table 22). Domestic passenger enplanements (58.6 million) reached an all-time September high, up 4.7 percent from the previous high (56.0 million) reached in 2015 (Table 23). International passenger enplanements (7.9 million) reached an all-time September high, up 1.4 percent from the previous high (7.8 million) reached in 2015 (Table 24).

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

Explanation of seasonal adjustment

Seasonal adjustment allows the comparing of monthly load factors to all other months. 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 79 carriers as of Dec. 7 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 http://www.transtats.bts.gov/TRAFFIC/

For additional scheduled service numbers for U.S. airlines, 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 Error! Reference source not found., U.S. carriers reported 89,755 foreign point-to-point passengers. For January through SeptemberError! Reference source not found., U.S. carriers reported 929,265 foreign point-to-point passengers.

Data are subject to revision. BTS has scheduled Jan. 13 for the release of October traffic data. None of the data are from samples so measures of statistical significance do not apply.