APPENDIX A 

METHODOLOGY FOR THE 2005 GENERAL AVIATION AND AIR TAXI ACTIVITY 

AND AVIONICS (GAATAA) SURVEY

Purpose of Survey

The purpose of the GAATAA Survey is to provide the Federal Aviation Administration (FAA) with 

information on general aviation and on-demand Part 135 aircraft activity. The information 

obtained from the survey enables the FAA to monitor the general aviation fleet so that it can, 

among other activities, anticipate and meet demand for National Airspace System (NAS) 

facilities and services, assess the impact of regulatory changes on the fleet, and implement 

measures to assure the safe operation of all aircraft in NAS. The data collected are also used by 

other government agencies, the general aviation industry, trade associations, and private 

businesses to pinpoint safety problems and to form the basis for critical research and analysis of 

general aviation issues.

Background and History

Prior to the first implementation of the annual GAATAA Survey in 1978, the FAA used the 

Aircraft Registration Eligibility, Identification, and Activity Report (AC Form 8050-73) to collect 

data on general aviation activity. The form was sent annually to all owners of civil aircraft in the 

United States and served two purposes: (1) Part 1 was the mandatory aircraft registration 

revalidation form, and (2) Part 2 was voluntary and applied to general aviation aircraft only, 

asking questions on the owner-discretionary characteristics of the aircraft such as flight hours, 

avionics equipment, base location, and use. The FAA used this information to estimate aircraft 

activity. 

In 1978, the FAA replaced AC Form 8050-73 with a new system: Part 1 was replaced by a 

triennial registration program. In January 1978, the FAA implemented a new procedure, known 

as triennial revalidation, for maintaining its master file. Instead of requiring all aircraft owners to 

revalidate and update their aircraft registration annually, the FAA only required revalidation for 

those aircraft owners who had not contacted the FAA Registry for three years. This less 

frequent updating of the master file affected its accuracy and representativeness: 

1. The accuracy of current owners and their addresses deteriorated. 

2. The master file combined a residue of aircraft, which under the old revalidation 

system would have been reregistered and purged from the file, but now remain 

under the new system. 

Part 2 of AC Form 8050-73 was replaced by the General Aviation Activity (GAA) Survey. 

Conducted annually, the survey is based on a statistically selected sample of aircraft, and it 

requests the same type of information as Part 2 of AC Form 8050-73. The first GAA Survey took 

place in 1978, collecting data on the 1977 general aviation fleet. 

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Appendix A: Methodology for the 2005 General Aviation 

and Air Taxi Activity and Avionics (GAATAA) Survey 

In 1993, the name of the GAA Survey was changed to the General Aviation and Air Taxi Activity 

(GAATA) Survey to reflect that the survey includes air taxi (that is, on-demand Part 135) aircraft. 

Starting in 1999, the avionics section, which was previously included only every other year, was 

asked every year. As a result, the survey’s name was changed to the General Aviation and Air 

Taxi Activity and Avionics (GAATAA) Survey. This is the name under which the 2005 survey 

was conducted. 

The GAATAA Survey has undergone periodic revisions to content, implementation, and 

definition of the GA population in order to remain current with regulations, activity patterns, and 

general aviation community. The table below summarizes changes in survey content. 

Year Description of change to survey content 

1993 Added sightseeing and external load to use categories 

1996 Added public use (i.e., flights for the purpose of fulfilling a government function) to use 

categories 

1999 Significant re-design of the entire survey form to reduce item non-response, add new 

content, and be compatible with optical scanning

Added air medical services to use categories 

Discontinued the use of a catch-all ‘other’ category as used in previous years 

Began collecting avionics data every year, rather than every other year 

2000 Public use asked as a separate question, independent of other use categories (e.g., 

personal/recreation, business transportation), because it was not mutually exclusive 

with respect to other flight activity 

2002 Use categories refined to be mutually exclusive and exhaustive and match definitions

used by NTSB for accident reporting

2004 Air medical services was divided into two separate types to capture air medical flights 

under Part 135 and air medical flights not covered by Part 135

A more clearly defined ‘other’ category was reintroduced 

2005 Fractional ownership question was changed from yes/no to a percentage 

Reduced the number of fuel type response categories by removing obsolete options

Added question asking for average fuel consumption (in gallons per hour) 

Revised avionics page by adding and rearranging items 

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Appendix A: Methodology for the 2005 General Aviation 

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The table below summarizes changes in survey implementation. 

Year Description of change to survey implementation 

1999 Non-respondent telephone survey conducted to adjust active aircraft and hours flown 

estimates1

Sample design revised to stratify by aircraft type (19 categories) and FAA region (9 

categories)2

2000 Discontinued non-respondent telephone survey because of the variability of telephone 

non-respondent factors 

Added Internet response option 

2003 Added a reminder/thank-you postcard between the first and second mailings 

2004 Introduced “multiple aircraft” summary form to allow owners/operators of multiple 

aircraft to report aggregate data for their entire fleet on a single form 

Phone calls placed by PA and aviation associations to encourage participation by large 

fleet operators 

The table below summarizes changes to the definition of the general aviation population and 

sample design. 

Year Description of change to definition of the GA population and sample design 

1993 Number of aircraft types classified by the sample was expanded from 13 to 19 

2003 Aircraft with known incorrect addresses and identified as “Postmaster Return” status on

the Registry were retained in the definition of the survey population and were eligible

for selection into the survey sample 

2004 Aircraft reported as “registration pending” or sold (if sold status less than 5 years) on 

the Registry were retained in the definition of the survey population and were eligible

for selection into the survey sample 

Sample design revised to stratify by aircraft type (19 categories), FAA region (9 

categories), and whether or not the aircraft is owned by an entity certified to fly Part 135 

(2 categories) 

Introduced 100% sample of the following groups: turbine aircraft, rotorcraft, on-demand 

Part 135 aircraft, and Alaska-based aircraft 

2005 Sample design and reporting revised by introducing Light-sport aircraft as a 20th 

aircraft type sampled at 100% 

The 2005 statistics in this report were derived from the twenty-eighth GAATAA Survey, which 

was implemented in 2006.

 

1

 Telephone surveys of non-respondents also were conducted in 1977, 1978, 1979, 1997, and 1998. Please refer to the 1999 

GAATAA Survey report for a full discussion of the telephone survey of non-respondents. 2

 Before 1999, the sample was stratified by aircraft type (19 categories) and state/territory (54 categories). 

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Appendix A: Methodology for the 2005 General Aviation 

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Improvements to the 2005 Survey

As part of ongoing efforts to improve the survey data, four key changes were made to the 2005 

survey: 

1. The field period opened on March 29, 2006, the earliest date since the large-scale 

survey re-design in 1999. 

2. To gather more accurate fuel consumption data, a question was added asking for 

average fuel consumption (in gallons per hour). 

3. In order to remain current with technological advances, the avionics section was 

revised by adding and rearranging items. 

4. Light-sport aircraft were added as a 20th aircraft type, and are reported as a 

separate category 

Each of these improvement is discussed in further detail in subsequent sections of this 

Appendix. 

Survey Population and Survey Sample 

The survey population for the 2005 General Aviation and Air Taxi Activity and Avionics Survey 

includes all civil aircraft registered with the FAA that are based in the U.S. or U.S. territories and 

that were in existence and potentially active between January 1 and December 31, 2005.3

 This 

includes aircraft operating under: 

• Part 91: General operating and flight rules. 

• Part 125: Certification and operations: Airplanes having a seating capacity of 20 or 

more passengers or a maximum payload capacity of 6,000 pounds or more (but not 

for hire). 

• Part 133: Rotorcraft external load operations. 

• Part 135: On-demand (air taxi) and commuter operations not covered by Part 121. 

• Part 137: Agricultural aircraft operations. 

Aircraft operating under Part 121 as defined in Part 119 are excluded from the survey

population. Foreign air carriers, which operate under Part 129, are also not part of the survey 

population. Civil aircraft that are known not to be potentially active during the survey year are 

also excluded from the population—i.e., aircraft displayed in museums, aircraft destroyed prior 

to January 1, 2005. 

 

3

 According to the FAA Aircraft Registration Master File—the sample frame for the survey (discussed below)--over 99 percent of the 

aircraft in the 2005 survey population were registered to owners in the 50 states, the District of Columbia, Puerto Rico or other U.S. 

territories, such as American Samoa, Guam, and the Virgin Islands. 

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Appendix A: Methodology for the 2005 General Aviation 

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The Aircraft Registration Master File, maintained by the FAA’s Mike Monroney Aeronautical 

Center in Oklahoma City, serves as the sample frame or list of cases from which a sample of 

civil aircraft is selected. The Registration Master File (“Registry”) is the official record of 

registered civil aircraft in the United States. For the purpose of defining the 2005 survey 

population, we used the Registry’s list of aircraft as of December 31, 2005. 

The Registry, like all sample frames, is an imperfect representation of the survey population. 

While it may exclude a very small number of aircraft that operate under the FAA regulations 

governing the operation of general aviation and on-demand Part 135 aircraft, it also includes 

aircraft that are not part of the survey population. Prior to sample selection, several steps are 

taken to remove ineligible aircraft from the sample frame. Specifically, this includes removing 

the following: 

• Aircraft missing key identifiers that are necessary for classification or merging with 

other data sources (e.g., N-number, serial number, make/model information) 

• Aircraft whose registration has been cancelled or revoked 

• Aircraft based in Europe or registered to a foreign company that have not returned 

flight hour reports 

• Aircraft that operate under Part 121 

• Aircraft destroyed or moved to museums prior to January 1, 2005 

• Aircraft reported sold before 2000 (5 years prior to survey year)4

• Aircraft that are flagged Postmaster Return (known to have incorrect address 

information) since before 1995 (10 years prior to survey year) 

• Aircraft that are missing information on the registrant’s name (i.e., the field is blank) 

(Aircraft for which the registrant is listed as “Pending” are retained in the survey 

population5

) 

• Aircraft that lack information necessary to execute the sample design (i.e., aircraft 

type, FAA region) 

The Registry included 359,516 aircraft as of December 31, 2005. After excluding the aircraft 

described above, the sample frame contained 298,901 records used to define the general 

aviation population. 

Sample Design

The 2005 GAATAA Survey Sample is stratified by aircraft type (20), FAA region in which the 

aircraft is registered (9), and whether the aircraft operates under a Part 135 certificate (2). Part 

135 aircraft were identified using the FAA’s Operations Specifications Subsystem (OPSS) 

 

4

 Prior to 2004, aircraft were excluded if reported sold more than 1 year prior to the survey year. 5

 Prior to 2004, aircraft with “Registration Pending” were excluded from the population. 

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Appendix A: Methodology for the 2005 General Aviation 

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database that was merged with the Registry by N-number. The three stratifying variables yield a

matrix of 360 cells. 

The 2005 survey sample included several types of aircraft that were sampled at a rate of 1.0 

(i.e., 100 percent sample). Because of the FAA’s interest in gaining a better understanding of 

the operation of these aircraft, all such aircraft listed in the Registry were included in the survey 

sample to ensure a sufficient number of survey completes to support analysis and provide more 

precise estimates of fleet size and aircraft activity. These include: 

• 100 percent sample of turbine aircraft (turboprops and tubojets) 

• 100 percent sample of rotorcraft 

• 100 percent sample of aircraft operating on-demand Part 135 

• 100 percent sample of aircraft based in Alaska 

Altogether, these aircraft contributed 42,543 observations to the 2005 survey sample. 

In addition to the four groups listed above, the 2005 GAATAA Survey tracked Light-sport aircraft 

as a 20th aircraft type for the first time. Because the survey universe contained only 193 Lightsport aircraft, these aircraft were also sampled at 100 percent. 

Other aircraft that are not part of a 100 percent sample are subject to selection based on 

sampling fractions defined for each cell in the sample design matrix. Average annual flight hours 

is the primary measure needed by the FAA to address survey goals. Sample fractions for each 

sample strata are defined to optimize sample size to obtain a desired level of precision for an 

estimate of flight activity. Data from the previous survey year on average hours flown, variability 

in hours flown by region and aircraft type, and response rates are used to set precision levels 

and identify the optimal sample size for each strata. Aircraft are randomly selected from each 

cell in the matrix, subject to the desired sample size. Strata that yield a very small sample size 

are examined and adjusted to include all observations in the strata if necessary. In 2005, an 

additional 34,667 aircraft were sampled at a rate of less than 1.0, yielding a total survey sample 

of 77,403. Table A.1 shows the number of aircraft selected into the survey sample, by aircraft 

type, as well as the proportion of the population represented by the sample. 

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Appendix A: Methodology for the 2005 General Aviation 

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TABLE A.1: SURVEY SAMPLE AND POPULATION FIGURES BY AIRCRAFT TYPE 

Aircraft Type Population

Sample 

Size

Sample as 

Percent of 

Population 

Fixed Wing - Piston 

 1 engine, 1-3 seats 64,841 15,618 24.1 

 1 engine, 4+ seats 128,059 14,531 11.3 

 2 engines, 1-6 seats 16,181 4,772 29.5 

 2 engines, 7+ seats 7,475 2,127 28.5 

 Piston: Other 227 227 100.0 

Fixed Wing - Turboprop

 1 engine 2,809 2,809 100.0 

 2 engines, 1-12 seats 4,806 4,806 100.0 

 2 engines, 13+ seats 977 977 100.0 

 Turboprop: Other 78 78 100.0 

Fixed Wing - Turbojet 

 2 engines 9,750 9,750 100.0 

 Turbojet: Other 1,027 1,027 100.0 

Rotorcraft 

 Piston 4,452 4,452 100.0 

 Turbine: 1 engine 5,891 5,891 100.0 

 Turbine: Multi-engine 1,322 1,322 100.0 

Other Aircraft 

 Glider 3,201 1,448 45.2 

 Lighter-than-air 7,160 1,823 25.5 

Experimental 

 Amateur 34,907 2,936 8.4 

 Exhibition 3,180 1,049 33.0 

 Experimental: Other 2,365 1,567 66.3 

Light-sport 193 193 100.0 

Total 298,901 77,403 25.9 

Weighting the Survey Data

Data from completed surveys are weighted to reflect population characteristics. The weights 

reflect the proportion of aircraft sampled from the population in each sample strata and 

differential response as well as a small adjustment for aircraft that are not part of the survey 

population. 

Initially, each aircraft for which we receive a completed survey is given a weight that reflects 

sampling fraction and differential response. That is: 

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Appendix A: Methodology for the 2005 General Aviation 

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WEIGHT = (Population Nijk/Sample Nijk) * (N Respondentsijk/Sample Nijk) 

where i, j, and k represent the three sample strata of aircraft type, FAA region, and Part 135 

status. 

The weight is subsequently adjusted to reflect new information about non-general aviation 

aircraft. That is, survey responses that identify an aircraft as not being part of the survey 

population—destroyed prior to January 1, 2005; displayed in a museum; operated primarily as 

an air carrier under Part 121 or 129; or a military aircraft—are used to remove aircraft 

proportionally from the sample and from the population. This adjustment is done at the level of 

the 20 aircraft types. The procedure assumes that non-GA aircraft occur in the same proportion 

among survey respondents and non-respondents. To the extent that non-GA aircraft are less 

likely to receive and complete a survey, this approach will underestimate the adjustment for 

aircraft that are not part of the general aviation population. 

Errors in Survey Data

Errors associated with survey data can be classified into two types—sampling and nonsampling errors. Sampling errors occur because the estimates are based on a sample of aircraft 

rather than the entire population, and we can expect, by chance alone, that some aircraft 

selected into the sample differ from aircraft that were not selected. 

Non-sampling errors can be further subdivided into a) errors that arise from difficulties in the 

execution of the sample (e.g., failing to obtain completed interviews with all sample units) and b) 

errors caused by other factors, such as misinterpretation of questions, inability or unwillingness 

to provide accurate answers, or mistakes in recording or coding data. 

Sampling Error

The true sampling error is never known, but in a designed survey we can estimate the potential 

magnitude of error due to sampling. This estimate is the standard error. The standard error 

measures the variation that would occur among the estimates from all possible samples of the 

same design from the same population. 

This publication reports a standard error for each estimate based on survey sample data. An 

estimate and its standard error can be used to construct an interval estimate (“confidence 

interval”) with a prescribed level of confidence that the interval contains the true population 

figure. In general, as standard errors decrease in size we say the estimate has greater precision 

(the confidence interval is narrower), while as standard errors increase in size the estimate is 

less precise (the confidence interval is wider). Table A.2 shows selected interval widths and 

their corresponding confidence. 

TABLE A.2: CONFIDENCE OF INTERVAL ESTIMATES 

WIDTH OF INTERVAL

APPROXIMATE CONFIDENCE 

THAT INTERVAL INCLUDES 

TRUE POPULATION VALUE

1 Standard error 68% 

2 Standard error 95% 

3 Standard error 99% 

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Appendix A: Methodology for the 2005 General Aviation 

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This report presents a “percent standard error” for each estimate, which is the standard error 

relative to the mean. The percent standard error is simply the ratio of the standard error to its 

estimate multiplied by 100. For example, if the estimate is 4,376 and the standard error is 

30.632, then the percent standard error is (30.632/4,376) * 100 = 0.7. Reporting percent 

standard errors makes it possible to compare the precision of estimates across categories. 

Estimates and percent standard errors reported in Table 2.1 provide an example of how to 

compute and interpret confidence intervals. To obtain, for example, a 95 percent confidence 

interval for the estimated number of total hours flown for turbojets in 2005, where the total hours 

flown is estimated to be 3,767,327 and the percent standard error of the estimate is 0.8, the 

following computation applies: 

Lower confidence limit: 3,767,327 – 2(0.8/100)(3,767,327) = 3,707,050 

Upper confidence limit: 3,767,327 + 2(0.8/100)(3,767,327) = 3,827,604 

In other words, if we drew repeated samples of the same design, 95 percent of the estimates of 

the total hours flown by turbojets would fall between 3,707,050 and 3,827,604. 

Non-sampling Error

Sampling error is estimable and can be reduced through survey design (e.g., by increasing 

sample size), but it is difficult, if not impossible, to quantify the amount of non-sampling error. 

Although extensive efforts are undertaken to minimize non-sampling error, the success of these 

measures cannot be quantified. 

Steps taken to reduce non-sampling error fall into two classes—strategies to reduce nonresponse and efforts to minimize measurement and coding errors. To this end, implementation 

and design of the 2005 GAATAA Survey incorporated the following steps to maximize 

cooperation among sample members: 

• Two modes of administration to facilitate access to the survey—a postcard invitation 

to complete the survey on the Internet followed by a mail survey to be completed by 

pen or pencil 

• Three mailings of the survey to individuals who had not yet responded, as well as a 

reminder/thank-you postcard 

• Cover letters accompanying each survey mailing clearly explained the purpose of the 

survey as well as the endorsement (organizational logos) of several aviation 

associations6

• Cover letters assured owners of the confidentiality of their responses and informed 

them: “Names of individuals are never associated with responses. There is an 

identification number on your survey only so [survey contractor] knows who should 

receive the survey.” 

 

6

 The following associations’ logos appeared on the 2005 cover letter: Aircraft Owners and Pilots Association (AOPA), Experimental 

Aircraft Association (EAA), General Aviation Manufacturers Association (GAMA), Helicopter Association International (HAI), National 

Agricultural Aviation Association (NAAA), National Air Transportation Association (NATA), National Business Aviation Association 

(NBAA), Small Aircraft Manufacturers Association (SAMA). 

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Appendix A: Methodology for the 2005 General Aviation 

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• Use of additional sources to obtain updated contact information and help ensure the 

mail survey reaches the sample member (e.g., National Change of Address, updates

from aviation associations) 

• Use of a toll-free 800 telephone number and email address to respond to questions 

• Collaboration with aviation organizations and industry groups to encourage 

cooperation of owners or operators of multiple aircraft 

The survey also reflects efforts to minimize measurement error by increasing the likelihood that 

respondents share a common understanding of survey questions and reducing errors in data 

coding. These include: 

• Close collaboration with the FAA, other federal agencies and aviation groups to 

refine and clarify question wording as well as definitions to questions. The 

questionnaire is re-examined each year to identify ambiguities or revisions necessary 

to remain consistent with aviation regulations and definitions.

• Significant reviews and re-designs of the questionnaire have been undertaken 

periodically (see “Background” section of this report). Each re-design is thoroughly 

pre-tested with a sample of aircraft owners or operators and, if necessary, modified 

on the basis of the pre-test results. 

• Comprehensive editing and verification procedures to ensure the accuracy of data 

transcription to machine-readable form as well as internal consistency of responses. 

Survey Content 

The 2005 GAATAA Survey questionnaire, shown in figure B.1 of Appendix B, requests the 

aircraft owner or operator to provide the following information on the sampled aircraft’s 

characteristics and uses: 

1. Number of total hours flown in 2005, and hours flown by use 

2. Airframe hour reading and the aircraft’s base location as of December 31, 2005 

3. IFR hours, percentage of hours flown in Instrument Meteorological Conditions (IMC) 

and Visual Meteorological Conditions (VMC) during the day and evening 

4. Number of landings in 2005 

5. Fuel type and average fuel consumption 

6. Whether the aircraft was part of a fractional ownership program in 2005 

7. Avionics equipage 

The survey questionnaire was largely unchanged from the 2004 survey to the 2005 survey, with 

the following exceptions:

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Appendix A: Methodology for the 2005 General Aviation 

and Air Taxi Activity and Avionics (GAATAA) Survey 

• The fractional ownership question (Q6) was changed from yes/no to a percentage. 

This allows hours flown by aircraft that operate only part of the time under a 

fractional ownership program to be reported proportionally rather than an “all or 

nothing” manner. Also, this item was moved to page 2 of the questionnaire. 

• Based on recommendations by the FAA and industry experts, the following fuel types 

were removed from Q15: propane, aviation fuel - 80 Octane, and 82 UL. 

• To gather more accurate fuel consumption data, a question was added asking for 

average fuel consumption (in gallons per hour). Prior to the 2005 survey, fuel burn 

rates were hard coded based on the 19 aircraft types. This procedure was adopted 

from earlier years, and the origin of the hard coded values is uncertain. The 

estimates presented in the 2005 GAATAA report are based on a new question 

(Q16), which asks respondents to report their average fuel consumption rate. This 

figure is multiplied by the total hours reported to calculate total fuel consumed. Fuel 

consumption estimates in 2005 should reflect differences by aircraft makes-models, 

use patterns, etc. more accurately. 

• In order to reflect technological advances, the avionics section was revised by 

adding and rearranging items. Items which were added to the 2005 survey include: 

- Integrated All-glass Cockpit 

- Electronic Flight Bag (EFB) - Installed 

- IFR LPV Approach (WAAS) 

- ADS-B (Mode S) 

- ADS-B (UAT) 

- Altitude Preselect 

- Attitude & Heading Reference System (AHRS) 

Survey Method 

Appendix B presents the materials used to conduct the 2005 survey. The standard survey form 

is shown in Figure B.1. The postcard invitation to the Internet component and the reminder/ 

thank-you postcard are shown in Figure B.2. Each of the three mailings for the standard survey 

was accompanied by a cover letter, shown respectively in Figures B.3, B.4, and B.5. 

The protocol used for the 2005 survey is similar to that used since the 2000 survey. The survey 

data were collected from owners and operators of the sampled aircraft through two venues – the 

Internet and mailings of the questionnaire. The Internet component was implemented before the

mailing portion to capture as many respondents electronically as possible. Sampled aircraft 

were first sent a postcard inviting them to participate in the Internet version of the survey. The 

postcard was sent out on March 29, 2006, and the Internet component continued through 

August 14, 2006. 

There were three mailings of the standard questionnaire, and a reminder/thank-you postcard 

sent between the first and second mailings. The first questionnaire mailing, sent out on April 26, 

2006, covered 52,330 aircraft in the sample that had not completed a survey via the Internet or 

had not received a final disposition due to a returned postcard (refused, respondent deceased, 

undeliverable with no new address, etc.). The reminder/thank-you postcard was sent on 

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Appendix A: Methodology for the 2005 General Aviation 

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May 17, 2006, and included only those aircraft in the sample that had not yet responded to the 

survey and were not part of the non-active sample. The second survey mailing was sent on 

June 1, 2006, and included only those aircraft in the sample that had not yet responded to the 

survey and were not part of the non-active sample. The third mailing was sent on July 6, 2006, 

to owners and operators of the sampled aircraft who had not responded to the first or second 

mailings. 

Alternative Survey for Reporting on Multiple Aircraft

The 2005 GAATAA Survey continued the effort initiated with the 2004 GAATAA Survey to 

increase cooperation among respondents who own or operate multiple aircraft. To achieve this 

objective, the 2005 survey employed the data collection tools and methods introduced in 2004. 

The responses of multiple-aircraft owners/operators are extremely important for accurately 

estimating general aviation activity. Because of the increased burden of reporting for multiple 

aircraft, there was a concern that these high-end, high-use operators were less likely to respond 

to the survey. Therefore, after the sample was selected, the FAA’s Operations Specifications 

Subsystem (OPSS) was used to group aircraft belonging to the same operator’s fleet. Operators 

with three or more aircraft were classified as “multiple owners/operators” for survey purposes, 

regardless of the number of their aircraft present in the survey sample. 

To avoid confusion among respondents, aircraft were assigned to a single data collection track. 

The 11,093 aircraft in the “multiple owner/operator” track followed an independent protocol 

developed last year. The remaining 66,310 aircraft followed the same protocol used in previous 

years and is described above. 

In order to minimize the reporting burden on operators of multiple aircraft, a summary survey

was developed with the cooperation of several aircraft operators and aviation associations to 

enable an operator to report activity for an entire fleet on a single condensed form, instead of 

completing the longer questionnaire for each individual aircraft. This survey form (Appendix B, 

Figure B.6) allows operators to report on key variables for major classes of aircraft, including

hours flown, how flown, fuel consumption, and number of landings. The form did not collect data 

on flying conditions, fuel type, fractional ownership, or avionics. 

Data collection for multiple-aircraft owners/operators followed the same timing as the standard 

data collection track. Like the standard survey protocol, an Internet survey that matched the mail 

questionnaire was programmed to allow online reporting. 

To maximize the survey response rate, follow-up phone calls were placed to all multiple-aircraft 

owners/operators. These calls focused not only on encouraging survey participation, but also on 

ensuring survey mailings were reaching the appropriate person in the operator’s organization. In

many cases, aviation associations with which operators had an existing relationship made these 

telephone calls. 

Benefits resulting from the new systems of data collection implemented since 2000 include 

quicker processing of the results, improved data quality, and considerable savings of time and 

money to both the public and the federal government. 

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Appendix A: Methodology for the 2005 General Aviation 

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Response Rate 

As shown in Table A.3, the overall response rate for the 2005 survey was 44.5 percent 7

. The 

response rate for the Internet portion of the survey was 18.9 percent and accounted for 41.9 

percent of the total responses to the survey. The first mailing had a response rate of 17.2 

percent and accounted for 30.5 percent of the total responses to the survey. The second mailing 

had a response rate of 9.6 percent, which accounted for 20.5 percent of the total responses to 

the survey. The third mailing produced a response rate of 7.3 percent, approximately 7.1 

percent of the total responses to the survey. 

TABLE A.3: SUMMARY OF RESPONSE INFORMATION 

Phase Valid Sample8 Completes9 Response Rate

% Total

Response 

 Internet 77,199 14,555 18.9% 42.5% 

 1st Mailing 66,203 11,395 17.2% 33.3% 

 2nd Mailing 52,426 5,037 9.6% 14.7% 

 3rd Mailing 44,337 3,238 7.3% 9.5% 

 Overall 76,902 34,248 44.5% 100.0% 

Table A.4 illustrates the steady increase in the Internet response as a percentage of all returned 

surveys from 2000 to 2005 (16.4 percent for 2000 compared with 42.5 percent for 2005). This 

increase in response illustrates an increasing effectiveness of utilizing the Internet for data 

collection, thereby improving the efficiency and cost savings of the data collection process. 

TABLE A.4: PERCENTAGE OF ALL COMPLETED SURVEYS RESPONDING BY INTERNET 

2000 2001 2002 2003 2004 2005

Total Completes 15,689 16,432 15,254 14,471 32,056 34,248

 Internet Completes 5,144 5,954 5,304 6,059 13,441 14,555 

 Internet % of Total 32.8% 36.2% 34.8% 41.9% 41.9% 42.5% 

 

7

 Although the 2005 response rate of 44.5% represents a decrease from response rates prior to 2003, this decrease is attributable to 

changes in survey methodology that have occurred over the past 6 years. The inclusion of bad addresses in the response rate 

calculation, adding more aircraft registered as “Sale Reported” or “Registration Pending” to the survey population, and other factors 

have resulted in the decrease to the response rate. 8

 Even though efforts are made to remove non-GA aircraft from the population before the sample is selected, a small number of 

surveys are returned each year indicating that the aircraft should not be part of the survey population (e.g., the aircraft was used 

primarily as a Part 121 air carrier, or was a museum piece the entire survey year). The Total Valid Sample Size used to compute the 

overall survey response rate excludes such aircraft. 9

 The total number of completes is not an exact sum of the separate components due to a small number of aircraft that did not 

receive a mailing but that were reported by a large fleet and therefore received a complete disposition. 

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Appendix A: Methodology for the 2005 General Aviation 

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A-14 

Table A.5 shows responses by aircraft type. 

TABLE A.5: RESPONSE RATE BY AIRCRAFT TYPE 

Aircraft Type Sample Invalid 

Sample10 Responses Response 

Rate 

Fixed Wing - Piston 

1 engine, 1-3 seats 15,618 112 7,557 48.7% 

1 engine, 4+ seats 14,531 66 7,195 49.7% 

2 engines, 1-6 seats 4,772 23 2,124 44.7% 

2 engines, 7+ seats 2,127 7 820 38.7% 

Piston: Other 227 2 48 21.3% 

Fixed Wing - Turboprop 

1 engine 2,809 19 1,337 47.9% 

2 engines, 1-12 seats 4,806 33 1,903 39.9% 

2 engines, 13+ seats 977 3 301 30.9% 

Turboprop: Other 78 1 18 23.4% 

Fixed Wing - Turbojet 

2 engines 9,750 49 4,301 44.3% 

Turbojet: Other 1,027 9 280 27.5% 

Rotorcraft 

Piston 4,452 31 1,449 32.8% 

Turbine: 1 engine 5,891 35 2,241 38.3% 

Turbine: Multi-engine 1,322 3 616 46.7% 

Other Aircraft 

Glider 1,448 10 700 48.7% 

Lighter-than-air 1,823 22 652 36.2% 

Experimental 

Amateur 2,936 36 1,509 52.0% 

Exhibition 1,049 29 464 45.5% 

Experimental: Other 1,567 10 611 39.2% 

Light-sport 193 1 122 63.5% 

Total 77,403 501 34,248 44.5% 

 

10 Even though efforts are made to remove non-GA aircraft from the population before the sample is selected, a small number of 

surveys are returned each year indicating that the aircraft should not be part of the survey population (e.g., the aircraft was used 

primarily as a Part 121 air carrier, or was a museum piece the entire survey year). The Invalid Sample represents such aircraft, 

which are excluded from response rate calculations.