DOT/FAA/AM-10/16

Office of Aerospace Medicine

Washington, DC 20591

OK-11-0024-JAH

Scott Shappell,1 Carla Hackworth,2

Kali Holcomb,2 John Lanicci,3

Massoud Bazargan,3 Jaclyn Baron,1

Rebecca Iden,1 Daniel Halperin3

1

Clemson University

Clemson, SC 29634

2

Civil Aerospace Medical Institute

Federal Aviation Administration

Oklahoma City, OK 73125

3

Embry-Riddle Aeronautical University

Daytona Beach, FL 32114

November 2010

Final Report

Developing Proactive 

Methods for General 

Aviation Data Collection

Federal Aviation

Administration
NOTICE

This document is disseminated under the sponsorship 

of the U.S. Department of Transportation in the interest 

of information exchange. The United States Government 

assumes no liability for the contents thereof.

___________

This publication and all Office of Aerospace Medicine 

technical reports are available in full-text from the Civil 

Aerospace Medical Institute’s publications Web site: 

www.faa.gov/library/reports/medical/oamtechreports
i 

Technical Report Documentation Page 

1. Report No. 2. Government Accession No. 3. Recipient's Catalog No. 

DOT/FAA/AM-10/16 

4. Title and Subtitle 5. Report Date 

Developing Proactive Methods for General Aviation Data Collection November 2010 

6. Performing Organization Code 

 

7. Author(s) 8. Performing Organization Report No. 

Shappell S,1 Hackworth C,2 Holcomb K,2 Lanicci J,3 Bazargan M,3 Baron J,1

Iden R,

1

 Halperin D3 

 

9. Performing Organization Name and Address 10. Work Unit No. (TRAIS) 

 

11. Contract or Grant No. 

1

Clemson University; Clemson, SC 29634

2

FAA Civil Aerospace Medical Institute; Oklahoma City, OK 73125 

3

Embry-Riddle Aeronautical University; Daytona Beach, FL 32114 

12. Sponsoring Agency name and Address 13. Type of Report and Period Covered 

 

 

 

Office of Aerospace Medicine 

Federal Aviation Administration 

800 Independence Ave., S.W. 

Washington, DC 20591 14. Sponsoring Agency Code 

15. Supplemental Notes 

Work was accomplished under approved task AM-HRR 521. 

16. Abstract 

Introduction. Over the last 20 years, nearly 40,000 general aviation (GA) aircraft were involved in accidents, 

roughly 20% of which were fatal. To address this safety concern, scientists have often relied on accident data. 

Because of the rare nature of accidents, commercial aviation incident and near miss data may prove to be useful 

sources of safety information. In one such study, the National Transportation Safety Board interviewed GA 

pilots that were flying near a weather-related accident in pursuit of a different perspective than that of the 

accident pilot. Interviewing GA pilots about their own weather-related event may provide similar benefits. 

Method. To understand factors leading GA pilots to encounter adverse weather conditions, pilots involved in an 

adverse weather encounter were interviewed using a one-hour structured interview. The interview was developed 

using surveys utilized by National Aeronautics and Space Administration and the Federal Aviation 

Administration (FAA). In total, 27 pilots who experienced an adverse weather encounter were interviewed, of 

which 25 were included in the final analysis. 

Results. Previous studies conducted by the FAA and others found many GA accidents involving flight into 

adverse weather were categorized as a willful disregard for the rules and regulations of safety; violations as defined 

by the Human Factors Analysis and Classification System. Contrary to what the accident record seems to 

suggest, flight into adverse weather may also be influenced by the lack of appreciation/understanding of the 

hazards associated with adverse weather. Perhaps some encounters with adverse weather were motivated by 

outside influences or exacerbated by some manner of mechanical failure that may have led to the willful 

acceptance of unnecessary hazards. 

Conclusions. These data suggest that current beliefs surrounding flight into adverse weather by GA pilots may be 

incomplete. The data presented here suggest that additional effort should be placed in training, both ab initio

and recurrent. Emphasis should be placed on ensuring a full understanding of the adverse impact of weather, 

including the recognition of instrument meteorological conditions, icing, convective events, etc. Likewise, with 

the proliferation of commercial weather products and on-board weather equipment, it may be time to move 

toward some form of standard weather package that all pilots would review before flying. 

 

17. Key Words 18. Distribution Statement 

 

 

General Aviation, Aviation Weather Encounters, Weather 

Knowledge, Pilot Education and Training

Document is available to the public through the 

Defense Technical Information Center, Ft. Belvoir, VA 

22060; and the National Technical Information 

Service, Springfield, VA 22161 

19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. Price 

Unclassified Unclassified 23 

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized 

iii 

ACKNOWLEDGMENTS

We are indebted to the many Flight Standards District Office employees that provided assistance beyond their 

normal duties to identify pilots as requested. As mentioned, this often involved additional searching on their part; 

we are very appreciative of their efforts and grateful for their commitment to aviation safety.

Research reported in this paper was conducted under the Flight Deck Program Directive / Level of Effort Agreement between the Human Factors Research and Engineering Group (AJP-61), Flight Standards Service – General 

Aviation and Commercial Division (AFS-810), and the Aerospace Human Factors Division (AAM-500) of the Civil 

Aerospace Medical Institute. This study was supported by FAA Cooperative Agreement Number 06-G-002. 

v 

Contents

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Method. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Participants. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Instrument. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Aircraft Demographics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Pilot Demographics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Event Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Preflight Planning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Enroute decision-making . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Procedures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Weather Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Pilot information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Pilot Certification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Flight Experience. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Physical and Mental Health. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Aircraft information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Preflight planning. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Route Planning. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Weather Planning. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Discussion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Conclusions and Lessons Learned. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Appendix A: Pilot Questionnaire. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A1

1 

Developing Proactive Methods for General Aviation Data Collection

INTRODUCTION

Operating a general aviation (GA) aircraft, particularly 

when flying cross-country, requires dedicated planning 

and decision-making involving such issues as the route 

of flight, terrain and obstacles one might encounter, and 

the threat of adverse weather. Some of these challenges 

remain fixed (e.g., terrain and other obstacles) and are 

relatively straightforward to address, while others, such 

as weather, are dynamic and can pose unique challenges 

to pilots. Indeed, even the best flight plans can prove 

inadequate or incomplete where the volatile nature of 

adverse weather is concerned.

Even with its unpredictable nature, pilots are still 

expected to fully understand the weather enroute and to 

avoid severe weather when planning and executing their 

flight (National Transportation Safety Board, 2006). 

Specifically, Title 14 Code of Federal Regulations (CFR) 

Part 91.103 mandates that when conducting a flight under 

instrument flight rules (IFR) or away from the airport 

pilots should become familiar with weather reports and 

forecasts (Federal Aviation Regulations/Aeronautical 

Information Manual, 2009).

Despite the regulations that require pilots to fully understand and appreciate the risk associated with adverse 

weather, weather-related GA accidents continue to occur. 

To put this in perspective, over the last 20 years, nearly 

40,000 GA aircraft have been involved in accidents; 

of these, roughly 20% involved fatalities (Shappell & 

Wiegmann, 2009). Notably, many of those fatal accidents 

involved encounters with adverse weather (Detwiler, 

Boquet, Holcomb, Hackworth, Wiegmann, & Shappell, 

2006; Wiegmann, Boquet, Detwiler, Holcomb, Faaborg, 

& Shappell, 2005; NTSB, 2005).

So, why would a pilot fly into adverse weather, particularly when the consequences can be so dire? Unfortunately, 

the answer continues to be debated among academics and 

regulators, alike. Some of the more prevailing explanations 

have recently been summarized by Wiegmann, Talleur, 

and Johnson (2008) and include:

• Lack of knowledge and experience (Goh & Wiegmann, 

2002; O’Hare & Owen, 2002; Wiegmann, Goh, & 

O’Hare, 2002)

• Poor pre-flight planning (Wiggins, Stevens, Howard, 

Henley, & O’Hare, 2002; Wiggins & O’Hare, 2003)

• Limited weather-evaluation skills (Goh & Wiegmann, 

2001; Wiegmann, et al., 2002; Burian, Orasanu, & 

Hitt, 2000; Wiggins & O’Hare, 2003)

• Low risk perception/overconfidence (Goh & Wiegmann, 2001)

• Poor in-flight planning (Detwiler et al., 2006; Stokes, 

Belger, & Zhang, 1990; Knecht, 2005)

• Inability to execute a 180 degree turn (Wiegmann & 

Goh, 2003; AOPA, 2004)

Some have even suggested that encounters with adverse 

weather represent the willful disregard for the rules and 

regulations (Wiegmann et al., 2005). After all, it is incomprehensible to some that a pilot who sees threatening 

weather in his path would elect to continue into it if a 

safer alternative is available. The problem with this latter 

view is that it is based upon accident data that are arguably limited, particularly when the pilot is fatally injured, 

and the exact causes of accidents are based as much on 

conjecture and expert opinion as they are on fact. 

Despite the uncertain nature of fatal accident data, 

aviation safety has historically been driven by accident 

databases archived and maintained by organizations like 

the National Transportation Board (NTSB) and Federal 

Aviation Administration (FAA). However, at some point, 

relying solely on accident data will yield fewer and fewer 

positive interventions – particularly as the historical accident rates are driven down to the level of rare events. 

This is precisely what has happened within the commercial aviation industry. As a result, emphasis within 

commercial aviation has moved from accident data to 

more proactive and normative data sources and risk 

analysis. For instance, programs like flight operations 

quality assurance (FOQA), the aviation safety action 

program (ASAP), and line operations safety audits (LOSA) 

have been developed and embraced by the commercial 

aviation industry.

At a minimum, these proactive and normative data 

sources have expanded our understanding of the human 

factors associated with commercial aviation accidents and 

incidents and have broadened how accident/incident 

causation is viewed. However, even established datacollection tools like these continue to be modified and 

have yet to be leveraged throughout the aviation industry 

– particularly GA where equipment, programs, and access 

are less regulated and standardized.

Left with few alternatives, many studies of GA flight 

into adverse weather have utilized simulation, surveys, 

and structured interviews. One particularly unique study 

of interviewed pilots was that they were flying in the vicinity of, but not directly involved in, a weather-related 
2 

accident (NTSB, 2005). This study was conducted to 

render a different perspective than that of the accident 

pilot, who in most cases is fatally injured. This represented 

a significant departure from traditional accident studies in 

that the pilots interviewed were not directly involved in 

the accident but were exposed to similar environmental 

conditions (e.g., weather and terrain). Among the more 

notable findings were:

• A pilot who starts flying earlier in life is at lower risk of 

being involved in a weather-related GA accident than 

those who start flying when they are older.

• Chronological age at the time a pilot obtains a license 

to fly is a better predictor of future accident involvement than age at time of flight.

• Periodic training and evaluation may be necessary to 

ensure that pilots maintain weather-related knowledge 

and skills. 

• GA pilots routinely consult other sources of aviation 

weather to obtain information that is not currently 

available from a standard weather briefing (i.e., Flight 

Service Station).

As useful as the NTSB study was, most would agree 

that information from a pilot involved with the adverse 

weather encounter would be even more valuable. The 

challenge is to identify a source of data involving actual 

pilot encounters with adverse weather. 

One relatively untapped source of information is nearmiss data. By definition, these are not accidents and, as 

such, the pilots involved are alive and can presumably 

recount their decision process. Of course, this assumes that 

those issues that influence performance during accidents 

also influence near misses in a similar way.

One such “near-miss” database already exists. The Aviation Safety Reporting System (ASRS) is an anonymous database that relies on self-reported incidents and near-miss 

data. However, ASRS reports are not necessarily focused 

on any specific type of incident or near-miss. Moreover, 

they require the individual to self-report, which may 

constrain submitted information, and certainly does not 

go to the level of detail required for a full understanding 

of pilot decision-making (Macrae, 2009). In sum, what 

is needed is a better understanding of exactly how and 

why a GA pilot would encounter adverse weather straight 

from the source – the pilot who made the decision and 

experienced the weather encounter. 

METHOD

Although there are more traditional ways to identify 

pilots who encountered adverse weather and survived 

(e.g., NTSB accident records and ASRS reports), this 

study employed two previously untapped resources: 1) 

the Administrators’ Daily Alert Bulletins that identify 

incidents, accidents, and pilot deviations on a daily basis, 

and 2) air traffic control flight assists. The latter occur 

when pilots request the assistance of air traffic controllers 

to navigate their aircraft or when an air traffic controller 

initiates an interaction with a pilot for safety purposes. 

Many of these interactions involving flight through or 

around adverse weather are reported to responsible FAA 

officials and were of particular interest. Monitoring these 

events is consistent with FAA order 8000.1, Safety Management System Doctrine, which states:

The safety assurance process continually assesses activity 

to identify new hazards and to ensure risk controls achieve 

their intended objectives throughout the system life cycle. 

New hazards may be those not identified during the SRM 

process or those introduced by the risk controls. This includes assessment of the need for new risk controls or to 

eliminate or modify risk controls that are ineffective or are 

no longer needed due to changes in the operational environment. Every SMS includes a process for continuously 

monitoring systems of interest to identify new hazards or 

the need to change risk controls or other risk management 

responses. These monitoring activities apply to an SMS 

whether the operations are accomplished internally or 

outsourced. (FAA Order 8000.1, Section 2-5.3.a.).

With both data sources, attention was paid to events 

involving visual flight rules (VFR) into instrument 

meteorological conditions (IMC), convective and icing 

encounters, and instrument-rated pilot control difficulties in actual IMC.

Participants

More than 175 events were reviewed, of which 115 

were included as candidates for this study. Scientists 

from the FAA Civil Aerospace Medical Institute (CAMI) 

contacted the Flight Standards District Office (FSDO) 

aviation safety inspectors (ASIs) responsible for the 

candidate events to describe the project objectives and 

request permission to communicate with the involved 

pilot. Note that in some cases no investigation had been 

conducted prior to CAMI contact. In total, more than 160 

ASIs from roughly 55 different FSDOs were contacted.

From the ASI inquiries, approximately 50 potential participants were identified and contacted via 

the telephone, E-mail, or postal mail, depending on 

the type of contact information received. After being briefed on the purpose of the project, including 

the anonymous nature of their responses, pilots who 
3 

agreed to participate were provided a consent form 

and scheduled for a telephone interview.

Twenty-seven pilots who experienced an adverse 

weather encounter were subsequently interviewed. Two 

pilot interviews were eliminated because one was interviewed during initial beta testing, and the other did not 

meet our research needs. This left 25 pilot interviews in 

the final analysis.

Instrument

The roughly one-hour interview was developed using 

surveys previously employed by the National Aeronautics 

and Space Administration (NASA) and the FAA (NASA, 

2007; Knecht, 2008a and 2008b). The structured interview included several items on basic aircraft and pilot 

demographics, a description of the event, preflight planning, and weather decision-making. A brief description 

of each section of the structured interview follows:

Aircraft Demographics

Pilots were asked standard demographic questions, 

such as the type of aircraft they were flying during the 

weather encounter and whether they leased, partially, or 

fully owned the aircraft.

Pilot Demographics

 In addition to traditional demographic questions 

like education, profession, gender, and age, several items 

regarding piloting experience and training were asked of 

the pilots. Specifically, they were asked: 

• When they first learned to fly

• The date of their most recent flight instruction

• The date of their most recent biennial flight review

• Class of medical certificate they held and whether any 

waivers or limitations were attached

• Ratings and certificates they held (e.g., single engine 

land, certified flight instructor, and instrument rating)

• Flight hours flown before the adverse weather encounter 

(total and 90 days prior to the event)

• Number of cross-country flight hours flown before 

the adverse weather encounter (total and 90 days 

prior to the event)

• Instrument flight hours flown before the adverse 

weather encounter (simulated and actual instrument 

flight)

• Type of equipment (e.g., weather-avoidance, terrainavoidance, autopilot, GPS, and de-icing) onboard 

the aircraft; if onboard, was it used during the flight 

and had the pilot received formal training for its use

• Whether they participated in FAA-sponsored WINGS 

programs

• Whether they obtained a good night’s sleep before 

the flight

• Whether they were suffering from any illness the day 

of the flight

Event Information

Pilots were asked to describe their weather encounter 

in detail. Several additional demographic questions related 

to the flight were also asked, including:

• Purpose of the flight (i.e., business or pleasure)

• Had they flown the route before and if so, how many 

times?

• Planned length of flight

• Departure airport

• Approximate temperature at departure

• Time of departure

• Planned destination airport

• Type of approach planned for destination (i.e., Visual, 

Cat I, II, or III)

• Planned alternate destination airport

• Whether they communicated with ATC or any other 

services (e.g., Flight Service Stations) while enroute

• In-flight services requested (e.g., an emergency climb/

descent, vectors to an airport or visual meteorological 

conditions (VMC), pilot reports (PIREPS), weather 

updates, or instrument approach procedures)

• Lighting conditions (e.g., daylight, night, dusk, dawn)

• Weather conditions (i.e., IMC, VMC, marginal VMC) 

at departure, enroute, and at the destination

• Time of arrival at their intended or alternative destination

Preflight Planning

Of particular interest in this study was the method 

of preflight weather planning employed by the pilots. 

Pilots were asked to describe their normal method of 

preflight planning and whether it was different the day 

of the weather encounter. They were also asked:

• Whether they attempted to obtain pre-flight weather 

information

• The last time they checked weather before flight

• Which weather providers they typically use when 

planning a flight (e.g., National Weather Service, 

flight service stations, direct user access terminal, and 

hazardous in-flight weather advisory service) and if 

those were used before the incident flight

• Were any attempts to obtain pre-flight weather information unsuccessful and if so, why?

• Whether the actual weather experienced was the same 

as, better, or worse than predicted when they departed, 

enroute, and at their planned destination

• Whether they considered the geography along the 

flight route (e.g., mountains and rising terrain)
4 

Enroute decision-making

Because all participants had encountered adverse 

weather, several questions were asked regarding their 

enroute decision-making. Specifically, pilots were asked:

• Whether they were under any pressure to get to their 

destination

• Whether they were aware of their course and location 

throughout the flight

• Whether there were any distractions in the cockpit

• Whether all the equipment was working during the 

flight

• What was their level of weather awareness during 

the flight

• What was their thought process upon entering the 

weather

• How did they feel upon encountering the weather

• Had they ever experienced similar weather conditions

• Whether they considered returning to their departure 

point or performing a 180 degrees to avoid weather

• Whether they had to divert from their planned destination and if so, was it before or after encountering 

the weather

• Whether they encountered the weather after reaching 

the half-way point of the flight

• What they did to prevent the encounter with weather 

from being worse

• Whether they would have done anything differently

Procedures

The structured interview was conducted using a 

conference call involving scientists from CAMI, Clemson University, Embry-Riddle Aeronautical University 

(ERAU), and the pilot participant. After reviewing the 

purpose of the interview and confirming the anonymous 

nature of the study and other elements of the informed 

consent, the roughly one-hour structured interview was 

conducted (see Appendix A for the actual structured 

interview questions). Responses were independently 

recorded for later comparison. Note that the interview 

was not audio-taped, only hand-written or typed notes 

of the interview were produced.

After the interview was completed, recorded responses 

were compared to ensure the accuracy of the record. A 

single consensus file was then sent to the pilot for review. 

This gave the pilot-participant an opportunity to ensure 

the accuracy of the recorded responses and to modify or 

clarify any responses given during the interview. Once 

the interview had been reviewed and accuracy ensured 

by all parties, the responses were combined with the 

others contained within a de-identified master database 

of pilot interviews.

Weather Information

In addition to pilot interview data, information was 

obtained regarding the atmospheric conditions during 

the time and at the location of each flight and weather 

encounter. Archived meteorological data associated with 

each event in the final database were obtained from the 

National Climatic Data Center. Relevant aviation weather 

reports were reviewed including: 

• Routine aviation meteorological reports (METARs)

• Terminal aerodrome forecasts (TAFs)

• Airman’s meteorological information (AIRMETs)

• Significant meteorological information/ advisories 

(SIGMETs)

• Precipitation reflectivity fields from the National 

Weather Service’s Doppler Radar Network

The METARs and TAFs were collected for the departure, destination, and encounter/diversion times and 

locations in each case. The AIRMETs, SIGMETs, and 

radar data were collected for the routes/times of flight, and 

the encounter times and locations were also documented. 

RESULTS

Pilot information

All pilots interviewed were male, ranging in age from 

20 to 72 years old, with an average age of 50 years. Ten 

pilots (40.0%) were between the ages of 40 and 59, and 

nine (36.0%) were 60 and over. All pilots had completed 

some college coursework and almost half (48.0%) had 

received graduate level training. Many of the pilot 

participants were employed as professional pilots or as 

business owners.

Pilot Certification

All pilots had a basic pilot certification of airplane 

single engine land and were medically certified to fly. 

Over half (60.0%) held a Class III (private pilot only) 

medical certificate, with the remaining pilots holding 

either a Class II (commercial, non-airline duties, and 

private pilot; 24%) or Class I (scheduled airline) medical 

certificate (16%). In addition to the single engine land 

rating, 36.0% of pilots held a multi-engine rating, 24.0% 

held a commercial rating, and 20.0% were certified flight 

instructors. Additionally, most of the pilots (76.0%) were 

instrument rated.

Flight Experience

Although flight experience varied greatly among the 

pilots, our pilot cohort can be considered experienced 

pilots. A summary of their flight experience is presented in 
5 

Table 1. As can be seen, experience varied greatly, ranging 

from 130 total hours to 20,000 total hours. The median 

for the group was 1,100 total hours of experience. Note 

that because of the wide range in flight hours, the median 

was viewed as the best measure of central tendency. Actual 

instrument flight time also varied markedly, ranging from 

4 to 2,970 hours with a median of 164 hours.

Most of the pilots (56.0%) first learned to fly within 

10 years of the adverse weather encounter. More than 

two-thirds of the pilots (68.0%) received some degree 

of formal flight instruction within the year prior to the 

weather encounter. However, two (8.0%) of the pilots 

had not received formal flight instruction in more than 

a decade. 

The majority of the pilots (80.0%) had completed at 

least one biennial flight review (BFR), and most (70%) 

had completed a BFR within 1 year of the weather encounter. It was also interesting that almost half (48.0%) 

of the pilots had participated in FAA-sponsored WINGS 

programs, which provide voluntary training to enhance 

pilot proficiency and safety. 

Physical and Mental Health

The majority of the pilots (92.0%) reported feeling 

well on the day of the weather encounter. Those who were 

feeling worse than normal that day reported allergies or 

were recovering from being sick a few days prior to the 

flight. However, all had obtained a good night’s sleep 

the night before the flight. Most did not feel pressured 

to get to their destination; however 20.0% of the pilots 

reported having some form of motivation to arrive at 

their planned destination (i.e., wanting to get home as 

soon as possible.)

Aircraft information

Not surprisingly, a variety of aircraft was represented in 

our sample. Most of the aircraft were owned by the pilot 

(60.0%). The remaining pilots flew either a companyowned (24.0%) or rental (16.0%) aircraft. 

Several types of aircraft were represented in this study. 

While most were single-engine, propeller-driven aircraft 

(e.g., Cessna, Beechcraft; 84.0%), there were a few multiengine aircraft (e.g., KingAir and Piper; 12.0%) and one 

Learjet. The top-three aircraft manufacturers were Cessna 

(32.0%), Piper (20.0%), and Mooney (16.0%). 

Almost all (96.0%) of the pilots had at least one GPS 

inside the aircraft. Approximately two-thirds (62.5%) of 

the aircraft had terrain avoidance equipment and over 

half (56.0%) had on-board weather-avoidance equipment. Almost half (44.0%) of the aircraft had de-icing 

equipment, and most (79.2%) were equipped with an 

autopilot. 

Preflight planning

Preflight planning is critical in every flight. Included 

in a comprehensive preflight are such things as the aeronautical integrity of the aircraft, engine maintenance, fuel 

quantity, route planning, alternate airports, and weather. 

While all are important, route planning, alternate airports, 

and preflight weather planning were of greatest concern 

in this study. 

Route Planning

Our sample included routes across a variety of geographical locations; however, most occurred in the Southern and Northwest Mountain regions, as defined by the 

FAA. A regional map of where the weather encounters 

occurred is presented in Figure 1. 

The majority of the flights (75.0%) took place during 

the day and were conducted mainly for business (40.0%) 

and pleasure (48.0%); the remaining flights were for 

multiple purposes (8.0%) and training (4.0%.) Most of 

the flights (80.0%) were planned to last up to 5 hours, 

with an average flight time of just more than 2 hours. 

The majority (76.0%) of pilots had planned a visual 

approach to landing at their destination.

All pilots considered the geography that they would 

encounter enroute and approximately two-thirds (64.0%) 

had flown the route before. Likewise, most (64.0%) of 

the pilots had planned an alternate airport in advance of 

Table 1. Pilot participant flight experience 

Median Minimum Maximum 

Total flight hours 1,100.0 130.0 20,000.0 

Total hours in event aircraft 

make/model 300.0 4.0 5,000.0 

Total hours in last 90 days 40.0 2.0 250.0 

Cross-country hours 700.0 35.0 14,000.0 

Cross-country hours in last 90 days 36.0 0.0 250.0 

Actual instrument hours (n=16) 164.0 4.0 2,970.0 

Simulated instrument hours (n=13) 45.0 10.0 242.0 

Total instrument hours (n=15) 145.0 7.0 3,000.0 

Note: Flight hours were rounded to the nearest tenth. 
6 

takeoff in the event of encountering difficulties enroute. 

While alternate airports may not be important when flying 

locally, most of these flights involved cross-country flying, 

and alternate airports should normally be considered. 

Weather Planning

All pilots had obtained some type of weather information prior to departure on the day of the weather encounter, 

and most (76.0%) accessed weather information less than 

30 minutes before departure. The sources that the pilots 

used to access weather information varied. However, 

only three pilots experienced difficulty accessing weather 

information in their typical manner; in those cases, weather 

information was obtained from alternate sources.

Pilots were also asked about the weather services they 

used during the day of the encounter and which services 

they typically used. However, after a few interviews, the 

questions were modified to increase the specificity of the 

pilot responses. Table 2 presents the number of weather 

services that the pilot participants used, both typically 

and on the day of the weather encounter. 

The data revealed that the pilots in this study “typically” used between one and nine weather sources to access weather information, with an average of 5.6 sources. 

Table 2. Number of pilots using the specified weather services on the day of the 

weather encounter and in general (n=22)1 

Number of Pilots 

Number of sources Used day 

of encounter 

Typically 

used 

1 0 1 

2 4 0 

3 6 4 

4 4 3 

5 2 2 

6 2 3 

7 4 3 

8 0 4 

9 0 2 

1

Note that the sample size is 22 because this item was added after the first interviews were complete. 

0

Arizona

California

Hawaii

Nevada

Western  

Pacific

Northwest

Mountain Southwest Central Great Lakes Southern Eastern New England

Alaska

Colorado

Idaho

Montana

Oregon

Utah

Washington

Wyoming

Arkansas

Louisiana

Oklahoma

New Mexico

Texas

Iowa

Kansas

Missouri

Nebraska

Illinois

Indiana

Michigan

Minnesota

North Dakota

Ohio

South Dakota

Wisconsin

Alabama

Florida

Georgia

Kentucky

North Carolina

South Carolina

Tennessee

Mississippi

Delaware

Maryland

New Jersey

New York

Pennsylvania

Virginia

West Virginia

District of

Columbia

Connecticut

Maine

Massachusetts

New Hampshire

Vermont

6 4 0 4 8 2 1

6

0

4

0

4

8

2

1

Figure 1. Location of weather encounters using FAA defined regions. 
7 

Indeed, roughly half (54.5%) of these pilots typically 

used six or more weather sources. 

That being said, on the day of the weather encounter, 

the pilots “actually” used slightly fewer weather sources–

between two and seven weather sources to obtain weather 

information, with an average of 4.2 sources. Moreover, on 

the day of the weather encounter, only 27.3% of the pilots 

used six or more weather sources – roughly half of what 

was reported as “typically” used.

The type(s) of weather service(s) used by pilots typically 

and on the day of the weather encounter were very similar 

(Table 3). For instance, the top three weather providers used 

on the day of the weather encounter were Flight Service 

Stations, National Oceanic & Atmospheric Administration 

(NOAA), and the Weather Channel. However, that is not 

the entire story, as all of the weather providers, except for 

one category, were used less frequently on the day of the 

event, compared to typical usage rates.

As can be seen from Tables 4 and 5, most flights were 

forecast to depart in VMC with the actual weather at 

departure the same or better than predicted. However, 

most of the pilots (60.0%) encountered adverse weather 

enroute, with almost two-thirds of the encounters (64.0%) 

occurring past the halfway point of the flight.

Instrument meteorological conditions (IMC) and icing were the two most frequently encountered weather 

conditions. Table 6 shows all types of weather encountered.

Most of the pilots (96.0%) reported being aware of the 

adverse weather and where it was headed. However, the 

majority of the pilots (96.0%) ended up entering the weather 

anyway. In fact, only a little more than half of those pilots 

(58.3%) even considered performing a 180 degree turn 

to return to the departure airport or an alternate airport. 

As expected, the majority of pilots (92.0%) deviated at 

some point from their planned route or altitude. The two 

pilots who did not deviate from their planned routes were 

Table 3. Weather services used that day and typically used, by number of pilots (n=22)2 

Used Day of Encounter Typically Used

National Oceanic & Atmospheric Administration 14 

63.6%

16 

72.7%

Flight Service Station 15 

68.2%

17 

77.3%

DUATS 11 

50.0%

12 

54.5%

Commercial vendor 11 

50.0% 

17 

77.3% 

Hazardous In-flight Weather Advisory Service 4 

18.2% 

9 

40.9% 

Transcribed Weather Broadcast 3 

13.6% 

5 

22.7% 

Pilots Automatic Telephone Weather Answering 

Service 

0 

0.0% 

1 

4.5% 

En Route Flight Advisory Service 6 

27.3% 

10 

45.5% 

Weather Channel 12 

54.5% 

16 

72.7% 

Other Pilots 6 

27.3% 

13 

59.1% 

2

Note that the sample size is 22 because this item was added after the first interviews were complete. 

Table 4. Weather forecast 

VMC Marginal VMC IMC 

Departure Airport 16 

(72.7%) 

3 

(13.6%) 

3 

(13.6%) 

En Route 8 

(36.4%) 

6 

(27.3%) 

8 

(36.4%) 

Destination Airport 13 

(61.9%) 

5 

(23.8%) 

3 

 (14.3%) 

Note: n= 22 data for the departure and en route forecasts and n=21 for the destination forecast 
8 

Table 5. Actual weather experienced as compared with forecasted weather3 

Better Same Worse 

Departure Airport 3 

(14.3%) 

16 

(76.2%) 

2 

(9.5%) 

En Route 2 

(9.5%) 

6 

(28.6%) 

13 

(61.9%) 

Destination Airport 0 

(0%) 

4 

(44.4%) 

5 

 (55.6%) 

3

Four pilot data points were missing for departure and en route (N=21). Many pilots did not make it to the 

intended destination airport (N=9). 

Table 6. Type of weather encountered4 

Percentage 

Thunderstorm 17.0% 

Icing 41.7% 

IMC 50.0% 

Non-Convective 

Turbulence 4.2% 

MVMC 8.0% 

4

Pilots encountered multiple types of weather; 

therefore, the sum of percentages equal more than 

100%. 

very close to their intended destination or on the taxiway 

at the destination airport when the weather encounter occurred. However, the majority who deviated (73.9%) did 

so after encountering the weather. Even though a majority 

of the participants deviated, 87.5% were aware of where 

they were relative to their course and location. 

The majority of the pilots (76.0%) reported that they 

had previously flown in similar conditions. 

Because many of the pilots were identified using air 

traffic controller flight assists, it is not surprising that 

all but one pilot (96.0%) communicated with air traffic 

control. A variety of in-flight services were requested of 

air traffic control and flight service. While a few (12.0%) 

pilots requested as many as five services, the majority 

of the pilots made only one (28.0%) or two (24.0%) 

requests in-flight. As illustrated in Figure 2, the most 

18.2 18.2

59.1

22.7

36.4

41.7

9.1

22.7

50

0

10

20

30

40

50

60

70

80

90

100

Climb/Descent

IFR Clearance

Vectors to Apt

Vectors to VMC

PIREPS

WX Updates

IAP

Other

Percentage of Interviews

Already Had an IFR Clearance

Figure 2. In-flight services requested. 
9 

commonly requested in-flight services were vectors to 

an airport, weather updates, and PIREPS. Interestingly, 

half of the pilots already had IFR clearance for the flight, 

and around one-third (36.4%) of the remaining pilots 

requested IFR in-flight. 

It is interesting to note that more than half of these 

weather encounters (56.0%) were exacerbated by equipment failures, which can have dramatic impacts on pilot 

decision-making. For example, in a series of studies involving GA pilots, Beringer & Harris (2007) were able 

to show that automation-related (i.e., runaway pitchtrim up and down, roll servo failure, roll sensor failure, 

and pitch drift up) and mechanical failures (e.g., failed 

attitude indicator) can result in the a variety of piloting 

errors resulting in the loss of the aircraft. Put simply, 

the presence of a mechanical malfunction increases the 

likelihood that an error will occur.

DISCUSSION

Human decision-making in general, and pilot decisionmaking in particular, is largely dependent upon three key 

elements: 1) information – is the information accurate 

and timely; 2) knowledge – does the individual have the 

requisite knowledge to utilize the information present; 

and 3) experience – has the individual obtained sufficient 

experience with a given situation or similar situations 

to make a correct assessment (Patterson & Shappell, in 

review). The likelihood that a decision will be successful 

is markedly reduced if any of these three components are 

absent or lacking. It can also be argued that motivation 

influences to what extent the three elements (information, knowledge, and experience) will be considered in 

the decision-making process.

With this in mind, the 25 weather encounters were 

classified into one of five categories using the interview 

data and narrative summary of the encounter provided 

by the pilot participants. The categories utilized were: 

•	 Motivation. Referred to by some as “get-home-itis,” 

some pilots feel pressured to get to their destination. 

That pressure can be either external or internal.

•	 Lack of complete weather information. In some 

instances, pilots do not receive complete weather information and/or do not recognize that the information 

provided is insufficient.

•	 Conflictingweatherinformation. In some instances, 

sources of weather information may be in variance. For 

instance, on-board NEXRAD radar may be indicating 

a break in convective activity, while ATC and/or Flight 

Service may report the same area as IMC.

•	 Lack of appreciation/understanding of the weather.

Some pilots may not understand the implications of 

the weather, or if they do, they may not appreciate 

the threat to flight safety that adverse weather poses. 

In effect, these pilots lacked a practical strategy for 

managing the weather hazard they faced.

•	 Not/applicable. This category was included to capture 

those encounters that could not be classified within 

the previous four categories (e.g., encounters due to 

mechanical failures).

As can be seen in Figure 3, roughly one-fourth of the 

adverse weather encounters were driven by the motivation of pilots to get to their destination. These instances 

may explain at least some of the violations that have 

been identified in the accident record by Wiegmann et 

al. (2005). However, the majority of adverse weather 

24.0

52.0

16.0

4.0 4.0

0

10

20

30

40

50

60

70

80

90

100

Motivation Lack of 

Appreciation/

Understanding 

of Weather

Lack of 

Complete

Weather 

Information

Conflicting 

Weather 

Information

N/A

Percentage of Interviews

Figure 3. Figure 3. Explanations for why pilots Explanations for why pilots fly into adverse weather. fly into adverse weather. 
10 

encounters were due to a lack of understanding/appreciation of the weather conditions (52.0%). Surprisingly, few 

adverse weather encounters were caused by incomplete 

or conflicting weather information (8.0%). Note that 

four weather encounters did not fit into any of the aforementioned categories. After revisiting the uncategorized 

(N/A) encounters, all but one could be attributed to a 

technological malfunction (e.g., a malfunctioning onboard weather radar).

What’s more, the lack of understanding/appreciation 

of the weather did not seem to be isolated to any specific 

type of adverse weather event (Table 7). That is, the lack 

of appreciation/understanding of weather was spread 

across weather hazards. In contrast, nearly all adverse 

weather encounters that involved misplaced motivation 

were coupled with general IMC, rather than the more 

dangerous convective weather. This suggests that when 

faced with exceptionally bad weather, motivation may not 

have as much influence on pilot behavior as originally 

thought. 

In general then, it would appear from this study that 

rather than willfully disregarding the rules, many of the 

pilots simply committed decision errors, as described 

within HFACS1

 (Wiegmann & Shappell, 2003). Indeed, 

these decision errors were consistent with many of the 

explanations of why pilots fly into adverse weather, provided by Wiegmann et al. (2008). Explanations such as 

the lack of knowledge and experience, poor pre-flight 

planning, limited weather evaluation skills, and poor 

in-flight planning all would contribute to decision errors 

and seem to corroborate the findings presented here.

1

The Human Factors Analysis and Classification System (HFACS) 

is a theoretically based tool for investigating and analyzing human 

error associated with accidents and incidents. HFACS was developed 

by expanding upon Reason’s (1990) “Swiss-cheese” model of human 

error. The basic premise underlying this taxonomy is that an accident 

is generally a series of events. The sequence of preceding events are 

purported to include both latent and active errors. The HFACS 

taxonomy defines 19 causal categories of human error whereby the 

accident’s progression is categorized. These categories are housed 

within four levels (i.e., unsafe acts, preconditions for unsafe acts, 

unsafe supervision, and organizational influences) of human error. 

See Wiegmann and Shappell (2003) for an in-depth description.

Does this mean that previous findings (e.g., Wiegmann 

et al., 2005; Detwiler et al., 2006) were flawed that suggested that many GA weather-related accidents are due 

to violations? Not necessarily. It could be that there are 

fundamental differences between fatal and non-fatal 

encounters with weather. Indeed, data from those studies 

suggest that most fatal weather encounters are associated 

with violations, while non-fatal weather encounters are 

more indicative of decision errors (Wiegmann et al., 2005; 

Detwiler et al., 2006). Obviously, the majority of events 

presented here did not involve accidents on fatalities. 

It can also be argued that the experience level of the 

pilots in this study was considerably higher than those 

GA pilots examined in previous analysis of the NTSB 

accident database (Goh & Wiegmann, 2002). Roughly 

40% of the pilots in the analysis of the NTSB accident 

database possessed an instrument rating, while a much 

larger proportion (76%) of the pilots in this study were 

instrument rated. 

On the other hand, and perhaps more troubling, it 

could be that the lack of available information following 

fatal weather encounters may bias investigators to resort 

to explanations more indicative of the willful disregard 

for the rules and regulations (i.e., violations). Without 

substantiating information from occupants of the aircraft 

or those with intimate knowledge of the pilot, field investigators are often left with little more than superficial 

descriptions of accidents that may lack the specificity 

required to rule out violations. Unfortunately, it will 

never truly be known what decisions were made in the 

cockpit when the pilots suffer fatal injuries. Indeed, there 

may be more to the story. This study showed how pilot 

decision-making and the lack of understanding of key 

weather information could easily lead to fatal accidents. 

For many, it was a matter of good fortune that under 

different circumstances (i.e., different amount of fuel, 

time of day, lack of ATC assistance, no hole in the cloud 

layer), the outcome could have resulted in a serious or 

fatal accident. 

It is noteworthy that the findings presented here seem 

to support those reported by the NTSB (2005). Recall 

that NTSB researchers interviewed pilots who were in the 

Table 7. Decision category by type of weather 

Hazard Lack of Appreciation/ 

Understanding of Weather Motivation Conflicting Weather Information 

Lack of Complete 

Weather 

Information 

IMC 5 4 0 1 

Icing 6 1 1 0 

Non-convective 

Turbulence 0 0 0 1 

Convective 

Weather 4 0 0 0 

Marginal VFR 1 1 0 0 
11 

general vicinity of those whose encounter with adverse 

weather resulted in a fatal accident. In contrast, the pilots 

interviewed in this study actually encountered the weather.

Consistent with the “accident pilots” in the NTSB 

study, many of the pilots interviewed in this study were 

older and started flight training later in life – both areas of 

concern identified by the NTSB (NTSB, 2005). Likewise, 

the data presented here regarding use of weather resources 

by pilots are consistent with that observed for pilots flying in the vicinity of the accident pilots. Specifically, the 

data presented here suggest that pilots utilize a variety 

of weather sources and that no identifiable “standard” 

approach to weather pre-flight planning appears to exist 

within GA. Unfortunately, it remains largely unknown 

what specific weather sources the accident pilots in the 

NTSB study utilized.

Given the proliferation of commercial weather products 

and on-board weather equipment, it may be time to move 

toward some form of standard weather package that all 

pilots would review before flying. Exactly what products/

equipment should be used remains to be defined; however, 

it is clear that some weather products and providers are 

considered more useful and/or are accessed more often 

than others (NASA, 2007). For instance, FSS, DUATS, 

and NOAA/NWS, were all utilized in both the NASA 

study and here. Similarly, Knecht (2008a) surveyed 230 

GA pilots from locations across the country (CA, OK, 

ND, IL, FL) and found that the FAA standard briefing 

was used on a majority of flights, followed by the NWS/

NOAA and DUATS. Beringer and Schvaneveldt (2002) 

found close agreement, for the most part, between the 

ratings of weather information items by both novice and 

experienced pilots. They recommended, based upon these 

findings, that one could develop algorithms, not unlike 

Pilot’s Associate, that would prioritize weather information by phase of flight for presentation on flight-deck 

displays, thereby potentially reducing display clutter and 

emphasizing salience.

Of course, simply accessing weather data does not 

necessarily mean that one paid attention to relevant 

information or that the information was even fully understood. It is sound and practical weather training and 

decision-making that can prevent accidents. For instance, 

Knecht (2008a) found that pilots spent an average of 17-20 

minutes reviewing information from weather products/

providers prior to departure and 7 minutes reviewing 

information while enroute. However, the bottom 5% of 

the pilots sampled only spent 5-7 minutes on products/

providers, and less than 2 minutes enroute. Whether or 

not relevant weather information can be extracted in 

such little time depends upon the nature of the weather 

and the end user’s proficiency. However, it is somewhat 

disconcerting that something as critical as weather information could be allotted only a few minutes during 

pre-flight planning and even less in-flight.

Unfortunately, similar information was not obtained 

in this study. What we were able to determine was the 

type of weather information pilots possessed or had available during the flight. Specifically, archival AIRMET/

SIGMET reports, weather radar data, and interview data 

made it possible to compare the information that pilots 

had versus the information actually available during the 

time of the encounter. An examination of the pilot responses in this study revealed that in most encounters there 

were more data sources available than the pilot actually 

accessed/obtained. In some situations, for example, the 

appropriate AIRMET/SIGMET was in effect along the 

route of flight and/or radar echoes were present, yet the 

pilot did not obtain them, or if they did, the information 

was misunderstood. 

It would appear that knowledge and training about 

specific weather products and what information they 

can provide might prevent encounters with adverse 

weather from happening in the future. On the surface, 

this recommendation may seem obvious and perhaps 

redundant, given that weather-related training is required 

of all pilots before licensure. However, a review of training requirements for weather hazards reveals that private 

pilot applicants “must receive and log ground training from 

an authorized instructor or complete a home-study course on 

... recognition of critical weather situations from the ground 

and in flight, windshear avoidance, and the procurement 

and use of aeronautical weather reports and forecasts” (14 

CFR 61.105). Even VFR-only pilots are given some 

instrument flight training as a precaution, so they can 

“maintain control of an aircraft while making a course 

reversal or diversion if they inadvertently enter clouds” 

(NTSB, 2005). 

The issue is not whether or not a pilot should receive 

meteorological training – the regulations clearly state 

that they should and requirements are in place to ensure 

training is provided. The better question is “How does 

one adequately educate and train a pilot applicant to 

guarantee that the aforementioned requirements are met?” 

There appears to be no standard in the case of educating 

pilots on meteorology and training them to use weather 

analysis and forecast products properly. In fact, the only 

specific hazard discussed in the regulations cited above 

is wind shear. An interesting comparison can be made 

to stall recovery and avoidance training. During primary 

flight training, the student receives hands-on experience 

in stalls. This is straightforward, as stall training can be 

easily introduced. Practical introductions to managing 

weather-hazard areas cannot be as easily simulated.
12 

One source of training materials and a useful resource 

is the Aeronautical Information Manual (AIM; FAA 

[2008]). The AIM includes a description of weather products as well as additional sources of weather information. 

However, while the AIM details many of these products, 

there are no specifics on what is required to be taught. It 

is unclear if pilots have been trained to interpret weather 

products adequately and make sound decisions based on 

their interpretation, or if they were taught just enough 

about each product to pass an examination. Should the 

latter scenario be the case, then it is possible that once an 

examination is over, a pilot may rarely consult some or 

all of these products in the future due to an incomplete 

understanding during initial training.

It is also interesting to note that a pilot can get all aviation weather questions wrong on the airman knowledge 

test (suggesting a total lack of weather knowledge), yet still 

pass the exam enroute to a private pilot’s license (Wiegmann et al., 2008; NTSB, 2005). Likewise, during the 

required biennial flight review (BFR), “... the instructor 

giving the flight review is free to determine the content; 

therefore, the BFR may or may not include a demonstration of the weather knowledge and instrument flight 

skills required for initial certification” (NTSB, 2005).

Therefore, it is conceivable that after becoming certified 

a pilot would not be capable of interpreting risks associated with adverse weather and throughout their career 

may never be required to demonstrate knowledge on 

aviation-specific weather information products. Perhaps 

what is needed is either a refinement of the current airman 

knowledge test requirements, required weather-related 

items on the BFR, or some new approach to weather 

instruction like scenario-based weather training/testing. 

Maybe then, an improved understanding of weather and 

its implications while flying can be fostered throughout 

the GA community.

Finally, it would be disingenuous to suggest that all 25 

adverse weather encounters were solely human factorsrelated, since more than half of the weather encounters 

were associated with some form of equipment failure. 

A sampling of the mechanical failures encountered by 

the pilots in this study included bad cells of an aircraft’s 

battery; malfunctioning communication and navigation 

equipment like the radios, VOR (VHF Omnidirectional 

Range), GPS, and DME (Distance Measuring Equipment)). In each case, the aircraft was still operational; 

however, at a minimum, the equipment failure(s) produced a distraction but, in some cases, exacerbated the 

encounter with adverse weather.

CONCLUSIONS AND 

LESSONS LEARNED

Although the data presented here embodied the collective experiences of 25 GA pilots who encountered 

adverse weather in flight, the data have limitations. For 

instance, the sample was small and does not directly 

reflect the regional distribution of pilots within the U.S. 

Specifically, none of the pilots in this study were from the 

Western-Pacific or Central Regions. Furthermore, even 

though the largest number of participants came from the 

Northwest Mountain Region, none of the pilots were 

from Alaska where GA aviation is a prominent form 

of transportation. Likewise, roughly 3/4ths of the pilots 

interviewed in this study held an instrument rating. This 

is similar to the Nall report’s findings that slightly over 

half of the pilots involved in weather-related accidents 

were instrument-rated (AOPA, 2008). 

It can also be argued that the pilots who volunteered 

to participate in our study did so because they felt that 

they simply made an honest mistake and did not willfully violate existing Federal Air Regulations (FARs). 

Whereas, the others who did not volunteer, may have 

declined because they knew that they were in violation and may have been reluctant to participate in an 

FAA-sponsored inquiry into why pilots fly into adverse 

weather. While it is impossible to know precisely why 

many pilots declined to participate (i.e., we did not ask 

them), it is possible that their participation would have 

increased the number of motivation-related encounters 

with adverse weather that may have driven the number 

of willful violations of FARs closer to those seen in 

previous GA accident studies. 

Nevertheless, the data presented here do shed additional light on the conundrum of why a GA pilot would 

fly into adverse weather. Contrary to what the accident 

record seems to suggest, flight into adverse weather 

seems to be primarily due to the lack of appreciation/

understanding of the hazards associated with adverse 

weather. Perhaps some encounters with adverse weather 

were motivated by outside influences or exacerbated by 

some manner of mechanical failure that may have led to 

the willful acceptance of unnecessary hazards. Simply 

put, there may be more to the story.

Furthermore, it would appear that additional effort should be placed in training, both ab initio and 

recurrent. Emphasis should be placed on ensuring a 

full understanding of the adverse impact of weather, 

including the recognition of IMC, icing, convective 
13 

events, etc. Moreover, we recommend a standard weather 

briefing that includes multiple, converging sources of 

information.

In addition to analyzing the interview data to determine 

trends and patterns, it was also our intent to develop 

disciplined methods for analyzing future accidents and 

incidents. Ideally, this would enable investigators to 

better learn from these incidents, improve correction of 

involved personnel, and generate interventions. Specifically, we planned to generate a list of items and/or data 

points for investigators to gain a better understanding of 

what happened within a particular weather event. The 

structured interview and weather information gathered 

met that goal.

We had also intended to derive a simple standard 

protocol aimed at identifying relevant weather-related 

events that could be used by Flight Standards or other 

research teams, but this did not happen. Unfortunately, 

identifying cases by reviewing lists of flight assists and 

weather events listed in The Administrator’s Daily Alert 

Bulletins was extremely time-consuming. 

Selecting a set of potential adverse weather encounters 

was only the first step. A great deal of work remained to 

identify the appropriate FSDO, gain access to pilot contact 

information, contact the potential pilot-participant, and 

garner informed consent. However, in some cases, the 

FSDO did not have contact information or they did not 

have a record of the event. This was surprising because, 

according to the FAA’s Air Traffic Quality Assurance 

process, flights assists are to be reported to the appropriate FSDO via the Regional Operations Center (ROC) 

within 3 hours of occurrence (7210.56C; FAA, 2002).

If the process of this study were to be duplicated 

or initiated as a proactive collection of near-miss data, 

the procedure would need to become formalized and 

streamlined across air traffic facilities and FSDOs. In 

addition, it would be useful if the standard flight assist 

form could be modified to archive key weather-related 

variables, many of which are identified within the structured interview used. Alternatively, the survey could be 

modified and streamlined for use by ASIs when conducting their investigations.
14 

REFERENCES

Aircraft Owners and Pilots Association (AOPA) Air 

Safety Foundation (2004). Spatial disorientation: 

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1., Frederick, MD.

Aircraft Owners and Pilots Association Air Safety Foundation (2008) 2008. Nall report: Accident trends 

and factors for 2007. Retrieved from http://www.

aopa.org/asf/publications/08nall.pdf

Beringer, D., & Schvaneveldt, R. (2002). Priorities of 

weather information in various phases of flight. 

Proceedings of the Human Factors and Ergonomics 

Society 46th Annual Meeting. 

Beringer, D., & Harris, H. (2007). Automation in general 

aviation: Two studies of pilot responses to autopilot 

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A1 

Appendix A

A. Aircraft Information

1. Aircraft Type

2. Aircraft ownership (Own (full or part), rent, other)?

B. Basic Aircrew Information (Confirming demographic data)

1. Age at time of incident

2. Education (HS, College, graduate)

3. Profession/Occupation

4. Gender

5. When did you first learn to fly?

6. Total Flight Hours

7. Flight Hours in Make/Model

8. Flight Hours in the last 90 days

9. Total Cross-Country Flight Hours (cross country defined as greater than 25nm from airport)

10. Cross Country Flight Hours in last 90 days

11. Ratings/Certificates

12. Are you instrument rated? If so, how much instrument experience have you had (simulated and actual)?

13. Do you participate in the WINGS program?

14. Date of most recent flight instruction

15. Year of most recent biennial flight review (BFR)

16. Date of most recent medical exam

17. Class of medical certificate (Class I, II, or III)

 a. Any waivers/limitations on the medical certificate

18. If you used any of the following equipment, have you had training on it? If yes, what kind and how much?

 a. Communication Equipment

 b. De-icing Equipment

 c. Weather-avoidance Equipment

 d. Terrain-avoidance Equipment

 e. Autopilot

 f. GPS

 g. Additional Avionics (i.e., Altitude alert, radar altimeters)

 h. Multifunctional Displays (i.e. GPWS, TCAS)

C. Event Information

1. Please describe the day of the flight.

2. What was the purpose of the flight? (air tour, business, emergency medical, ferry, freight, passenger, pleasure, 

training)

3. Have you made this trip before? If so, how many times?

4. Preflight

 a. What is your normal method of preflight planning 

 b. Was your method of preflight planning on the day of the incident different from normal?

 c. Did you attempt to obtain pre-flight weather information?

 1. If yes, when was the last time you checked weather before flight

 d. Did you have an alternate plan with alternate airports worked out in advance?

 e. Did you consider the geography along the flight route (e.g. mountains, rising terrain, etc.)? 

 f. Which weather provider(s) were used? 

 1. National Oceanic & Atmospheric Administration (NWS)

 2. Flight Service Station

 3. Direct User Access Terminal Service (DUATS)
A2 

 4. Commercial Vendors

 5. Hazardous In-flight Weather Advisory Service

 6. Transcribed Weather Broadcast (TWB)

 7. Pilot Automatic Telephone Weather Answering Service

 8. En-route Flight Advisory Service

 9. The Weather Channel

 10. Other Pilots

 11. Other (please specify):

 a. What type of information did you gather?

 g. What weather providers(s) do you typically use?

 1. National Oceanic & Atmospheric Administration (NWS)

 2. Flight Service Station

 3. Direct User Access Terminal Service (DUATS)

 4. Commercial Vendors

 5. Hazardous In-flight Weather Advisory Service

 6. Transcribed Weather Broadcast (TWB)

 7. Pilot Automatic Telephone Weather Answering Service

 8. En-route Flight Advisory Service

 9. The Weather Channel

 10. Other Pilots

 11. Other (please specify):

 h. Were any of your attempts to obtain pre-flight weather information unsuccessful? If yes, why?

 1. Did not know or were unable to find telephone or access numbers

 2. No telephone available

 3. No answer on telephone

 4. Telephone briefer did not have all requested information available

 5. Telephone briefer denied service

 6. No online access available

 7. Could not connect online

 8. Could not maintain online connection

 9. Required information not available on computer

 10. Experienced difficulty with computer interface

 11. Other (please specify)

 i. What was the preflight weather forecast for the following?

 1. Departure airport (VMC/Marginal VMC/IMC)

 2. En-route (VMC/Marginal VMC/IMC)

 3. Destination airport (VMC/Marginal VMC/IMC)

 4. Did not obtain a preflight weather briefing

 a. If you did NOT attempt to obtain pre-flight weather information prior to departure, why not?

 i. Did not believe pre-departure weather was necessary

 ii. Was intimidated by process of obtaining weather

 iii. Did not know or was unable to find telephone or access number

 iv. No Telephone available

 v. No online access available

 vi. Other (please specify)

 j. What was the planned length of flight?

 k. Where did you depart from and when?

 l. Where did you arrive and when?

 m. What type of approach was planned for your destination? (CAT I, CAT II, CAT III)
A3 

 n. Did you get a good night’s sleep the night before?

 o. How were you feeling on the day of the flight (e.g. sick, allergies, etc)?

5. In-flight

 a. What were the environmental conditions?

 1. Lighting conditions? (Day, Night, Dawn, Dusk, Cloudy, Sunny, Bright, Dark, etc...)

 2. Weather

 3. Temperature (degrees Fahrenheit)

 b. What was the weather like?

 1. At departure

 2. At destination

 3. During the Route

 c. Were you under any pressure to get to your destination?

 d. Did you have to deviate from the planned route or altitude?

 1. If yes, was it before or after you encountered weather?

 e. Were you aware of your course and location throughout the flight?

 f. Did you communicate with ATC?

 g. Did you communicate with any other en-route services (e.g. flight service stations)?

 h. What in-flight services did you request?

 1. Emergency climb/descent

 2. IFR clearance

 3. Vectors to an airport

 4. Vectors to VMC

 5. PIREPS

 6. Weather Updates

 7. IAP

 8. Other (please specify)

 i. Were there any distractions in the cockpit? (e.g., passengers, malfunctions.)?

 j. Was all the equipment working during the flight?

 k. What was your level of awareness of the weather (e.g., Did you know where the bad weather was headed?)

6. Upon encountering the weather

 a. During what point of the flight did you encounter weather?

 1. Was the pilot past the midpoint of the flight before realizing there was trouble?

 b. Was the actual weather better than, the same as, or worse than forecasted

 1. Departure (Better/Same/Worse)

 2. En-route (Better/Same/Worse)

 3. Destination (Better/Same/Worse)

 c. Can you explain your thought processes upon encountering the weather?

 d. Can you explain how you felt upon encountering the weather?

 e. Did you enter the weather? 

 1. If yes, did you consider flying a 180? 

 f. Have you ever experienced similar weather conditions in-flight?

 1. If yes, what did you do?

D. CONCLUDING THOUGHTS

1. Is there anything that you feel we should know?

2. What did you do that prevented this incident from being worse?

3. Knowing what you know now, would you have done anything differently?