1

Introduction

The problem of substance use disorders in the United States is profound. National estimates indicate that 15.4 percent of the U.S. adult population had a substance use disorder during 2020 (Substance Abuse and Mental Health Services Administration [SAMHSA], 2021). Of that total, the most prevalent condition was alcohol use disorders, although opioid use continues to be a major national concern. The National Institutes of Health defines a substance use disorder as “a treatable mental disorder that affects a person’s brain and behavior, leading to their inability to control their use of substances like legal or illegal drugs, alcohol, or [prescription] medications” (National Institute of Mental Health, n.d.). For the purposes of this report, the committee defined substance misuse as substance use that is problematic from a health, policy, or regulatory perspective, regardless of whether such use meets the diagnostic threshold of a substance use disorder. Substance misuse also includes using substances in inappropriate settings, such as the workplace, or in high doses (McLellan, 2017).¹

The negative consequences of substance use disorder or misuse can affect virtually all aspects of a person’s life: physical and mental health, cognitive ability, relationships, finances, and career. The physical health effects can include sleep difficulties, liver disease, heart disease, cancer,

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¹ While not a universally adopted term, the committee chose to follow the precedent of the Department of Health and Human Services (HHS), the Centers for Disease Control, and the Surgeon General in using “substance misuse” in this report to describe the broad spectrum of problematic substance use from a policy/regulatory perspective that might not rise to the diagnostic threshold of a substance use disorder.

respiratory issues, and even death. Acute intoxication slows reaction times and causes impairments in balance, motor skills, and judgement. The long-term effects of substance use disorder can include cognitive and neurological impairment. In addition to the above effects, clinical substance use disorders can compromise social functioning, leading to isolation, conflict, and broken trust in relationships. They also affect productivity, as evidenced by increases in sick days at work and job loss. Finally, substance misuse is associated with failure to meet financial responsibilities such as mortgage payments.

The cognitive and neurological impacts of alcohol use disorder are varied and wide-ranging. Some of the more common effects include memory impairment, difficulty with abstract thinking, disinhibition, and difficulty with decision-making (Bates et al., 2013; Evert & Oscar-Berman, 1995; Nixon, 1995). Long-term heavy use of alcohol can lead to permanent changes in the brain, including damage to the hippocampus and other areas associated with memory and learning (Modell & Mountz, 1990). In people without acquired tolerance, impairments for complex skills can start to occur at blood alcohol levels of 0.025 percent. Alcohol doses at the 0.05 percent level have been shown to affect gross motor control and orientation. In addition to cognitive effects, alcohol use disorder can cause neurological effects, such as seizures, tremors, and impaired coordination (Modell & Mountz, 1990).

Because substance use disorders can affect people’s work in all professions and jobs, there is reasonable concern about workers in transportation, especially in aviation, given the responsibilities those workers hold for the lives of others. While there is little validated data for this population, it has been suggested that the prevalence rate of substance use disorders for pilots may be similar to that of the general population (Porges, 2013). With this as context, in 1974 the Human Intervention Motivational Study (HIMS) began as a program to support pilots with a grant to the Air Line Pilots Association, International (ALPA) from the National Institute on Alcohol Abuse and Alcoholism. The Flight Attendant Drug and Alcohol Program (FADAP) was then initiated in 2010 to provide guidance and resources for flight attendants. Available data from these programs, although limited, confirm alcohol as the substance misused most often among program participants; greater than 80 percent of people treated under FADAP were suffering from alcohol use disorder. Similarly, limited data from HIMS show that greater than 90 percent of the pilots participating in HIMS had an alcohol use disorder. Regarding the use of stimulants (methamphetamines and cocaine), the rates were roughly 16 percent in FADAP and about 4 percent in HIMS. A very small share (2% or less) of pilots and flight attendants misused opioids. Nevertheless, the limited data available from aviation events provide reason for concern about the potential impacts of

prescription medication or illicit opioid misuse, particularly when combined with an opioid epidemic that continues in the general population of the United States.²

Currently the Bureau of Labor Statistics estimates that 48,750 active commercial pilots are employed by airlines (Bureau of Labor Statistics [BLS], 2022a) and 108,480 flight attendants are employed by the airline industry (BLS, 2022b). Given the national substance use disorder prevalence rates of 13 to 15 percent, one might expect that between 6,300 and 7,300 pilots would meet diagnostic criteria annually and that a considerably larger number could engage in substance misuse that does not meet diagnostic thresholds. Likewise, these data suggest that between 14,100 and 16,200 flight attendants could meet criteria of a diagnosable substance use disorder.

The Federal Aviation Administration (FAA) Reauthorization Act of 2018 required the secretary of the U.S. Department of Transportation (DOT) to enter into an agreement with the National Academies of Sciences, Engineering, and Medicine to conduct a study on HIMS and FADAP and other DOT drug and alcohol programs: see Box 1-1 for the complete statement of task.

Within the National Academies, three units participated in the study: the Board on Behavioral, Cognitive, and Sensory Sciences in the Division of Behavioral and Social Sciences and Education; the Transportation Research Board; and the Health and Medicine Division. The committee appointed to carry out the study was composed of experts with the range of skills and backgrounds necessary to assess the workings of programs such as FADAP and HIMS, including psychiatrists and psychologists who focus on the treatment of people with substance use disorders in safety-sensitive occupations, psychologists who regularly evaluate pilots participating in HIMS, evaluation specialists, professionals who oversee state regulation of safety-related professions involving the transportation industry, and health economists.

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² Concerns over the impact of substance misuse have been heightened by FAA investigations of civil aviation crashes that show a strong association of such events with evidence of substance misuse. The prevalence of potentially impairing substance use in aviation has frequently been measured by toxicology reports of pilots who died in aviation accidents. For example, in the area of drug use, data from the FAA Civil Aerospace Medical Institute’s Forensic Sciences Laboratory toxicology database and the National Transportation Safety Board’s aviation accident database were used to examine trends in the prevalence of over-the-counter, prescription, and illicit drug use by pilots during the years 1990–2012, and during follow-up years, 2013–2017. Findings of the two analyses showed increasing trends in the proportions of study pilots testing positive for at least one drug categorized as potentially impairing, used to treat a potentially impairing condition, or as a controlled substance (National Transportation Safety Board, 2020).

CONTEXT

Because of the high safety and security demands inherent in piloting, the FAA has instituted a multipronged approach to protect the public and the aviation workforce, recognizing that flying a commercial airliner engages all neurocognitive domains. A pilot operates a complex machine in an environment susceptible to rapid change affected by weather conditions, plane mechanics, geography, air traffic, time of day, and other human factors. Pilots must be prepared to rapidly respond cognitively and physically to altered circumstances in planes traveling at high speeds; thus any major impairment, whether associated with substance disorder or misuse, could

jeopardize the lives of everyone onboard.³ Flight attendants, too, must be prepared to respond quickly and effectively in high-pressure situations that can change abruptly.

Pilots must meet health standards. Commercial airline pilots must also have a first-class airman medical certificate.⁴ The evaluations for these certificates are performed by aviation medical examiners. Part of this medical examination is a record of the pilot’s behavioral health history, which includes any substance dependence or abuse as defined by the FAA.⁵

Key definitions and requirements for the first-class airman medical certificate include the following:

• For the FAA, “substance” includes alcohol, other sedatives and hypnotics, anxiolytics, opioids, central nervous system stimulants such as cocaine and amphetamines, and other psychoactive drugs.
• For the FAA, “substance dependence” means a condition in which a person is dependent on a substance, other than tobacco or ordinary xanthine-containing (e.g., caffeine) beverages, as evidenced by any one of the following:
  • increased tolerance;
  • manifestation of withdrawal symptoms;
  • impaired control of use; or
  • continued use despite damage to physical health or impairment of social, personal, or occupational functioning.
• The FAA also requires that pilots not have a record of substance abuse within the preceding two years. Flight attendants must pass random drug tests and function at expected levels.

If a pilot is experiencing problematic alcohol or other substance use, the FAA has measures in place to encourage them to seek the help they need. Pilots cannot be medically cleared to fly by the FAA if they have an alcohol use disorder, and they may face criminal charges if they report to work in a compromised state. Airlines are required to conduct random alcohol testing before flights, and very few pilots fail those tests (DOT, 2021).

It is important to note that, as discussed in detail in Chapter 2, the FAA definition of “dependence” is grounded in concerns about safety and functional impairments that are associated with use of certain substances,

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³ While there are numerous fatalities in general aviation, including recreational aviation, due to substance use-related impairment, major crashes of commercial airlines are extremely rare in the modern era of flight and there is no publicly available dataset on near misses.

⁴ For more on this certificate, see https://www.ecfr.gov/current/title-14/chapter-I/subchapter-D/part-67/subpart-B/section-67.101

⁵ For more on the mental health standards for airmen, see https://www.ecfr.gov/current/title-14/chapter-I/subchapter-D/part-67/subpart-B/section-67.107

even if substance use does not reach the levels that would meet the criteria for a diagnosis as defined by classification systems like the Diagnostic and Statistical Manual, Fifth Edition. For this reason, we follow conventions used by SAMHSA and refer to problematic use of drugs and alcohol as substance misuse.

HIMS and FADAP are designed to address substance misuse and substance use disorders among pilots and flight attendants, respectively. Training an airline pilot is an especially long, arduous, and costly process (BLS, 2022c), and therefore carriers have strong incentives to rehabilitate pilots who develop a substance use problem, as opposed to simply firing and replacing them. HIMS was established to assess the viability of an alcohol treatment and recovery program for pilots; it is a cooperative structure that includes airline representatives, pilot peer volunteers, health care professionals, and FAA medical specialists: see Box 1-2. It has evolved from a study into a professional monitoring program that seeks to coordinate the identification and treatment of pilots with substance use disorders as well as a return-to-work process for them, all under the FAA Special Issuance Regulations, and therefore carriers have strong incentives to rehabilitate pilots who develop a substance use problem, as opposed to simply firing and replacing them.

The mission of FADAP as published on its website is “to support a culture of safety which will be able to assist flight attendants in meeting their personal and professional goals through substance-abuse awareness, combined with self and peer referrals for assistance, and the implementation of a flight-attendant-specific recovery support system”⁶ (see Box 1-3).

STUDY APPROACH

The committee took note that HIMS and FADAP are prominent in the statement of task. Furthermore, the committee learned through its research, consultations with experts, and discussions with the study sponsor that HIMS is considered the gold standard among programs that address substance use disorders within the global transportation

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⁶ For more on FADAP, see https://www.fadap.org/

industry.⁷ The committee also learned through its consultations that an impetus for the study was its potential to offer lessons from the HIMS and FADAP that could guide practice and policy for a range of transportation-related safety-sensitive occupations. Thus, the committee began by developing a complete understanding of the context within which the HIMS and FADAP operate and assessing the information available about the programs’ operations and outcomes. It found, however, that evidence about the effectiveness of HIMS and FADAP is largely absent, and that the available information did not consistently support the conclusion that these programs should necessarily serve as models for other segments of the transportation industry. The committee decided to focus therefore on the HIMS and FADAP. Given the time available to conduct the study, in contrast with the kind of in-depth study of the programs and professional contexts of each mode that would be required to make recommendations about potential changes to practice and policy, the committee could not focus as much on other transportation industry programs.⁸

To further its understanding of HIMS and FADAP, the committee assembled information on the histories and the design of the programs, including their current structure and operating processes. The information gathered included available published reports on the programs, answers to the committee’s questions about the programs from FAA officials, and discussions with parties that oversee and participate in the programs. Examination of the program context also included:

• attending annual meetings of the two programs;
• a public convening that included a human resources official from United Airlines to provide an example of how an EAP coordinates with HIMS and FADAP, as well as a small number of program participants and stakeholders; and
• responses to questions from program participants, primarily from FADAP.

The committee members met six times over a 12-month period to receive invited presentations in public meetings and to deliberate and apply their collective expertise in closed sessions. Subgroups of the committee met throughout this period on an as-needed basis to assess the information

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⁷ Information from a committee-hosted public workshop, available https://www.nationalacademies.org/event/11-01-2022/workshop-on-dealing-with-substance-use-disordersand-strengthening-well-being-in-commercial-aviation

⁸ For a description of selected relevant programs in transportation, see Appendix A. The practices identified in this report are applicable, at least generally, to safety-sensitive transportation professions, but how to implement them depends on the professional context of each mode and would require in-depth study.

gathered and the implications for addressing the questions in the Statement of Task. The committee also commissioned papers from several outside experts to augment its own expertise. It further considered documentation of organizational structure and program details as provided by the FAA, HIMS, and FADAP leadership and by other government agencies. Information about programs of other transportation modes was gathered from relevant DOT agencies that responded to the committee’s inquiries. Individuals who provided briefings and testimony to the committee and the topics covered, as well as the papers commissioned by the committee, are presented in Appendix B. Because a central feature of both FADAP and HIMS is the facilitation of clinical interventions for substance use disorder misuse, the committee reviewed literature, including research on substance-related problems among people employed in safety-sensitive occupations, on substance use disorders among flight attendants and pilots, and, as noted earlier, on evidence-based treatments. One commissioned paper focused on a clinical review of evidence on medication-assisted treatments⁹ for substance use disorders, measuring the impairment effects of substance treatment that is medication-assisted, because the clinical practice of prescribing medication is subject to debate as it applies to the treatment of pilots and flight attendants (Kay & Belanger, 2022). The second commissioned paper undertook a quantitative analysis of the data received from FADAP (Nordberg, 2022). Because no source data were received from HIMS, the committee relied only on the very limited publicly reported information on pilots. The last paper is a qualitative analysis of responses from the “Call for Perspectives” and a series of focused follow-on interviews with 35 of the flight attendants and a single pilot (Wisdom, 2022).

Finally, the committee also received briefings from experts in the science of treating substance use disorders.¹⁰ Some of those speakers emphasized special considerations that arise when treating people in safety-sensitive occupations. The purpose of these efforts was to support the committee members in putting the processes and interventions used by HIMS and FADAP into the context of modern evidence-based clinical practice for addressing any type of substance misuse and its application to safety-sensitive occupations. Because alcohol is the primary drug that is misused

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⁹ Medication-assisted treatment (MAT) is also known as medications for substance use disorders, generally, or more specifically as medications for alcohol use disorder (MAUD) and medications for opioid use disorder (MOUD). The committee used MAT for clarity and readability as it is commonly known in the field and used by HHS and FDA. However, the committee acknowledges that SAMHSA uses MOUD and MAUD and those terms will likely be more prevalent in the future.

¹⁰ For more information, see the “Commissioned Papers” tab on the report webpage https://nap.nationalacademies.org/catalog/27025/substance-misuse-programs-in-commercial-aviation-safety-first

by pilots and flight attendants, the committee emphasized outcomes associated with alcohol misuse for alcohol use disorders.

Another source of information pursued by the committee was data from FADAP and HIMS. The committee reviewed publicly reported information from the two programs and analyzed program data that were made available to it. Publicly available reports provided a limited set of statistics on HIMS participants, such as treatment referral sources, substances misused, and rates of successful treatment and relapse. The committee requested access to the detailed program data to carry out the statistical analyses that are basic to evaluating any program, but it encountered multiple impediments to obtaining HIMS data for review and analysis. This included refusal by the FAA to share detailed HIMS data. In addition, the ALPA, which maintains the HIMS database through a contract with the FAA, refused to grant access to the data. In an effort to address concerns about data confidentiality and security, the committee proposed that ALPA conduct the committee’s requested analysis on the de-identified data, but this proposal was denied. Finally, the committee’s request to the FAA to compel HIMS to provide the relevant data was also denied, despite the contract stating that the data are owned by the U.S. government. Thus, after these repeated and varied efforts, the committee was unable to obtain source data regarding HIMS or have analyses conducted on its behalf by ALPA staff, and was, therefore, unable to review, analyze, and assess this program.¹¹ For a summary of communications regarding access to the HIMS database, see Appendix C.

As described above, the committee’s work was constrained by a lack of access to complete data on pilots participating in HIMS. This is important for several reasons. First, lack of data made it difficult for the committee to interpret the limited publicly reported program results we were able to review. Without access to these data the committee cannot, for instance, resolve questions that arose during the study about the quality of HIMS

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¹¹ During a Zoom meeting on April 27, 2022, with National Academies staff, the HIMS program manager offered to share queries and results from the HIMS database; follow-up attempts to agree on a data-sharing agreement that had specific confidentiality protections did not receive a response from HIMS. Following multiple requests, ALPA’s HIMS Advisory Board denied the committee’s request for data from the FAA-funded HIMS database on November 3, 2022, asserting the aforementioned contract with the FAA and concerns over confidentiality and data disclosure that might erode program integrity. A copy of the FAA/ALPA contract for HIMS was received by the committee on December 14, 2022. After review of the contract, the committee noted that the FAA owned the data, not ALPA, and indicated that access to the data would assist the National Academies in fulfilling the congressional mandate. During a followup meeting with National Academies staff on December 21, 2022, the FAA did not refute the National Academies’ assertions about the FAA having full ownership of the HIMS data; nevertheless, the FAA noted that full access would not be provided. Rather, the FAA offered to make available aggregate data related to HIMS. Those aggregate data were never delivered.

data and data systems. Those questions were based on aggregate data reported by FAA and HIMS suggesting potential weaknesses in reporting or data quality or both. Second, the committee could not assess the ability of HIMS to effectively monitor and manage its operations, a concern that stemmed from claims about rates of relapse and statistics on referrals from annual medical evaluations reported by the FAA about HIMS. Finally, the committee was unable to fully assess the qualitative data it received from the “Call for Perspectives” in light of the quantitative data, as it could do to a limited extent with FADAP. Comparing qualitative and quantitative data is required, because qualitative reports from successful participants in a program are typically based on self-selected respondents and therefore may not offer reliable indications of a program’s efficacy. In pursuing its charge, the committee sought to address a series of issues related to the ability of the FAA, HIMS, and FADAP to identify cases of substance use disorders, their approach to addressing those conditions, the degree to which the approach conforms with contemporary clinical science, and how the programs perform in promoting safety and returning pilots and flight attendants to work.

Identification of People in Need of Treatment

There are several ways that pilots and flight attendants are identified as having a problem in need of treatment. Those include failed random testing; self-referral; referral by family, friends and peers; events involving law enforcement (e.g., driving under the influence); referrals for suspicious behavior by Transportation Security Agency officers; and identification and referral by the employee’s airline or union. The DOT and the FAA require random testing of people performing safety-sensitive functions, including flight attendants and pilots. The implementation of that testing program is left to airlines and unions, however. A key question is to what extent problematic substance misuse is identified through the detection and referral mechanisms associated with FADAP and HIMS. The committee was unable to completely answer this question due to lack of data, but, as an example, it could ascertain from the available information that 0.5 percent of pilots are referred by aviation medical examiners during mandated annual screenings. Given an estimated prevalence rate of 15.4 percent (SAMHSA, 2021), a referral rate of 0.5 percent implies a case detection rate of less than one half of one percent. As mentioned previously, this observation raises questions such as the effectiveness of screening procedures and the quality of data and data reporting.

The Role of FADAP and HIMS in the Ecology of Aviation Safety and Healthcare

HIMS and FADAP are only two parts of a complex array of mechanisms for addressing substance use disorders in aviation. Moreover, there are vast differences between the two programs, with each having distinct structures and operating procedures and carrying very different employment and cost consequences for their participants. Other key institutions include EAPs run by unions and airlines, standard health insurance that covers and pays for treatment, mutual support groups such as Alcoholics Anonymous and SMART Recovery, and private financial resources. HIMS facilitates treatment for about 1.4 percent of all pilots (Skaggs & Norris, 2021),¹² even though their own estimates on the prevalence rate for substance use disorders is 8–12 percent.¹³ That means HIMS only accounts for a small fraction of pilots with substance use disorders. The data produced by FADAP highlight the fact that some of the largest carriers do not appear to participate in the FADAP (see Chapter 2). These observations mean that the FAA, the unions, and the HIMS and FADAP likely have limited visibility into both the degree to which substance misuse problems are identified and the treatment approaches taken, and outcomes realized for the total pilot and flight attendant population. Neither the programs nor the committee were positioned to offer insights into these issues due to the incomplete data of uncertain quality.

Heavy Reliance on Inpatient and Residential Treatment Modalities

Both HIMS and FADAP rely heavily on treatment in inpatient and residential settings. In addition to this reliance, the FAA and HIMS find MATs unacceptable for ongoing treatment of substance misuse. The committee focused on understanding the degree to which the clinical content of HIMS and FADAP aligns with modern evidence-based treatment for substance use problems. In contemporary evidence-based practice for the treatment of some substance use disorders, MAT is a first-line intervention (e.g., opioid use disorder and alcohol use disorder), and it is even considered advantageous in avoiding relapse and, in the case of opioids, in preventing overdose with appropriate medication selection and monitoring (U.S. Food and Drug Administration [FDA], n.d.). Where departures from evidence-based approaches exist, the committee sought to understand the extent to which those departures may be grounded in and justified by the unique circumstances of safety-sensitive occupations.

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¹² Based on the percentage of active pilots that have a substance use disorder-related special issuance in 2018. Another 0.37 percent of pilots were monitored for misuse.

¹³ Information from the 2023 HIMS, available at https://himsprogram.com/

HIMS and FADAP Make Strong Assertions for Their Successes

Strong assertions of success include HIMS noting that the model has been adopted by more than 40 airlines across the United States, as well as in Canada and eight other countries around the world. HIMS also asserts a return of nine dollars for every program dollar of spending and an “85 percent long-term abstinence rate.”¹⁴ Opportunity to examine the evidence supporting such statements is fundamental for determining the extent of HIMS’ success and whether the model should be extended elsewhere in the transportation sector, as was asked of this National Academies committee. Thus, the committee sought to confirm that these assertions are grounded in evidence, but the combination of incomplete data and questions about data quality and departures from evidence in the literature precluded the committee from being able to fully form conclusions related to this part of its charge.

ORGANIZATION OF THE REPORT

Following this introduction, Chapter 2 provides the history and descriptions of HIMS and FADAP. Chapter 3 covers the scientific evidence on practices in treatment programs for substance use disorders, and Chapter 4 reviews the key components in evaluating such programs. Chapter 5 turns to the committee’s analysis of the evidence about HIMS and FADAP, and Chapter 6 presents the committee’s conclusions and recommendations.

There are several appendixes to this report. Appendix A documents the information collected on other substance use disorder programs in transportation. Appendix B details the various avenues for data gathering to help assist the committee in its deliberations. Appendix C outlines the timing of the committee’s requests for access to data through various programs and offices. Appendix D provides brief biographies of the committee members. Finally, Appendix E notes the unavoidable conflict of interest in the committee membership.

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¹⁴ Ibid.

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