Form 41, Schedules T100 and T100(f) Air Carrier Data

Data Scope

The T-100 and T-100(f) databases include traffic data (passenger and cargo), capacity data and other operational data for U.S. air carriers and foreign air carriers operating to and from the United States. At the most detailed level, the databases provide monthly traffic and operational data for each air carrier, for each city-pair market that the carrier operated, and monthly traffic, capacity and operational data for each aircraft type that the airline flew in each city-pair flight segment, which is also known as a flight stage, or a flight leg. The T-100 and T-100(f) data files are not based on sampled data or data surveys, but represent a 100 percent census of the data.

Data Collection

Methods - Pursuant to 14 CFR Part 217 and Part 241, data are collected by the Office of Airline Information (OAI) within the Bureau of Transportation Statistics (BTS) on the Form 41, Schedule T-100 -- U.S. Air Carrier Traffic and Capacity Data By Nonstop Segment and On-flight Market and Form 41, Schedule T-100(f) -- Foreign Air Carrier Traffic and Capacity Data by Nonstop Segment and On-flight Market.

Large, certificated air carriers, small certificated air carriers, and commuter air carriers (each defined below) are required to complete Form 41 Financial and Traffic Reporting Requirements. These forms are completed both electronically (mainly by the large carriers) and on paper (small and commuter carriers).

Large Certificated Air Carriers - An air carrier holding a certificate issued under section 401 of the Federal Aviation Act of 1958, as amended, that: (1) Operates aircraft designed to have a maximum passenger capacity of more than 60 seats or a maximum payload capacity of more than 18,000 pounds; or (2) conducts operations where one or both terminals of a flight stage are outside the 50 states of the United States, the District of Columbia, the Commonwealth of Puerto Rico and the U.S. Virgin Islands.

Small Certificated Air Carriers - An air carrier holding a certificate issued under section 41102 of the Federal Aviation Act of 1958, as amended, that provides scheduled passenger air service within and between only the 50 States of the United States, the District of Columbia, the Commonwealth of Puerto Rico, and the U. S. Virgin Islands with small aircraft (maximum passenger capacity of 60 seats or less or a payload capacity of 18,000 pounds or less.)

Commuter Air Carriers - An air taxi operator that carries passengers on at least five round trips per week on at least one route between two or more points according to its published flight schedules that specify the times, days of the week, and places between which those flights are performed.

Schedule and Process - The Form 41 requirements are tiered based on the carriers’ annual operating revenue. The reporting groups are as follows:

• Group III - over $1 billion in annual operating revenues
• Group II - from $100,000,001 to $1 billion in annual operating revenues
• Group I Over - from $20,000,001 to $100,000,000 in annual operating revenues
• Group I Under - $20,000,000 or less in annual operating revenues

All carriers, except Group I Under carriers, submit quarterly Balance Sheet, P&L, Changes in Financial Position, and Operating Expense Reports. These reports are due at DOT 40 days after the end of the calendar quarter. These reports are made available to the public after the DOT performs edits on the data. This usually takes two weeks. Group I Under carriers submit semiannual Balance Sheet, P&L, and Operating Expense Reports, which are due at DOT 40 days after the end of the reporting period.

All carriers submit monthly income statements which are due at DOT within 30-days after the end of the applicable month. The purpose of the monthly reports is to allow DOT to monitor changing trends within the air transportation industry. Carriers do not close their corporate books to complete these reports. Therefore, users of the data should consider the numbers to be ‘ballpark figures’ rather than precise amounts. For this reason, the sum of the three monthly income statements may not equal the amounts on the quarterly income statements. The monthly reports are not released to the public until the applicable quarterly report is released.

All carriers, except Group I Under air carriers submit monthly fuel reports, which are due within 20-days after the end of the applicable month. Submissions are reviewed for the reasonableness of the price per gallon. These reports are available to the public within 2 to 3 weeks.

All large certificated air carriers submit monthly segment and market traffic data and quarterly enplanement and operations statistics. These reports are due at DOT within 30-days after the end of the applicable month or quarter. Data are edited by DOT for accuracy. Data are available for public release 30 days after receipt by DOT.

Response Rates - While some carriers must be reminded to submit their data, all carriers are required by law to respond. Hence, these data enjoy an almost 100 percent response rate.

Sampling Errors

Not applicable. Data are collected from each member of the population of interest.

Nonsampling Errors

The T-100 and T-100(f) systems were developed to provide complete and accurate data regarding domestic air travel within the U.S. and international air travel between the U.S. and foreign countries. The databases have been changed periodically to reflect changing data needs as well as developments within the airline industry. The data are routinely examined to uncover nonsampling errors and a process is in place to correct inaccurate or incomplete data. All data are subject to nonsampling errors. This name is given to any error not due to sampling that arises in data. Types of nonsampling errors that may be present in these data include:

Nonentry Error - A monitoring system is in place to track the data reporting of current air carriers and new air carriers as they begin airline operations. To prevent nonentry errors in the form of entire records that might have been omitted (as opposed to fields within each record), edits are performed to compare the reported data with other independent data sources such as the Official Airline Guide. When nonentry errors are detected by the OAI, the OAI contacts the air carrier with a formal notice of the nonentry error, and has established follow-up procedures to ensure that the data are reported, or the carrier is referred to the DOT General Counsel’s Enforcement Office for appropriate sanctions, fines or penalties.

Duplicate Entry Error - Duplicate data entries are possible but edit programs have been designed to check for these errors. Corrective action is taken by the OAI Data Base Administrator (DBA) for the detected errors, including requiring air carriers to file revised reports, where necessary, or obtaining carrier concurrence with the DBA’s corrective action.

Missing Data - Because of the high volume of data, it is possible that some data elements might be missing from the originally reported data. Edit programs have been designed to prevent missing data in the form of omitted fields within records (as opposed to complete records that have been omitted). When missing data errors are detected by the OAI DBA, the DBA contacts the air carrier about the error, and has established follow-up procedures to ensure that the data are reported, or the carrier is referred to the DOT General Counsel’s Enforcement Office for appropriate sanctions, fines or penalties.

Response/Measurement Error - Edit programs have been designed to test the reported data for various types of incorrect information. Corrective action is taken by the OAI DBA for the detected errors, including requiring air carriers to file revised reports, where necessary, or obtaining carrier concurrence with the DBA’s corrective action.

Coding/Recording Error - Edit programs have been designed to eliminate coding and recording errors. Corrective action is taken by the OAI DBA for the detected errors, including requiring air carriers to revise reports, where necessary, or obtaining carrier concurrence with the DBA’s corrective action.

Verification and Validation

To facilitate accurate data collection and reporting, the OAI has designed and distributed a computerized program that aids air carrier personnel in gathering the data. Additional data verification and validation occur mainly through the use of computerized editing programs that compare the reported data to a range of parameters involving the operations, city-pair markets and aircraft fleets of individual air carriers as well as other factors. The validity and accuracy of the reported data are assessed by the OAI DBA by the use of comparisons to test the consistency of the current period reported data with prior periods, and unit rates and cross-data edits are calculated to ensure that the reported data are reasonable.

For instance, where an aircraft has a total capacity of 100 passenger seats, and the transported passengers are reported as 200, an error calculation traps or highlights such errors for corrective action by the DBA. Also, where the collected or calculated T-100/T-100(f) data include both the miles flown and the hours flown by aircraft type (such as a B-747), a miles per hour calculation is performed to determine whether the reported data are reasonable, and the OAI DBA resolves any significant variances in this edit, and in many similar edits and validations, with the reporting air carrier. The T-100 and T-100(f) data are also compared to other independent data sources (including the related Form 41 financial data) to verify and validate specific data items. The data are used frequently in analyses and studies and, if these analyses indicate possible data inaccuracies, a system is in place to reexamine and obtain any necessary significant corrections of the original data.