Back to Table of Contents | June 2011

Clinical and Health Affairs

When Is it Safe to Fly? Addressing Medical Conditions in Pilots

By Lawrence Steinkraus, M.D.

■ Since World War I, the role of physicians who care for pilots has been to minimize the risks posed by the unique environment in airplanes and the demands of flying. Originally, that meant screening out those with any physical limitations that might affect their ability to fly such as vision or cardiac problems. Today, however, with the ability to better manage patients with multiple conditions, the physician’s task is more nuanced and requires an estimation of risk based on the how well a pilot’s condition can be managed and the type of flying he or she does. This article looks at how pilots are medically evaluated and how the standards for medical certification are evolving, allowing some pilots who have certain conditions to continue flying.

Mr. B is a 60-year-old airline pilot who needs to renew his first-class Federal Aviation Administration (FAA) medical certificate in order to continue flying. He has a history of prostate cancer, hypertension, type 2 diabetes mellitus, hyperlipidemia, coronary disease (he’s had coronary artery bypass grafting) as well as adjustment disorder with depressed mood that remains clinically quiescent. Mr. B is taking a number of medications including a beta-blocker, aspirin, lisinopril, metformin, and simvastatin. He has been doing well and is followed annually as required by the FAA’s Special Issuance program, which mandates specific testing for each of his diagnoses. As part of the renewal process, he has been scheduled to see a urologist, an endocrinologist, and a cardiologist. A prostate-specific antigen test, lipid profile, hemoglobin A1C, electrocardiogram, and graded exercise test have been ordered.

Once the evaluation is completed, an Aviation Medical Examiner (AME), a physician certified by the FAA to award medical certificates, will perform the appropriate forensic examination, complete the necessary documentation, and submit the findings as well as lab reports, consultant notes, and other data to the FAA. If all tests indicate his conditions are stable, Mr. B will receive his medical certificate.

Caring for patients with multiple medical conditions is challenging. Caring for pilots with multiple conditions is even more so, as the physician has the added responsibility of understanding which conditions may affect flight safety, with the primary concern being sudden incapacitation during flight. It is a challenge that is becoming more common, as the number of older pilots increases. According to the FAA, the average age of civilian pilots has been rising slowly over the last decade.¹ In addition, because we can now successfully treat diseases that would have been life-shortening in the past, standards with respect to aviation and medical status have changed. As a result,

the number of pilots requiring Special Issuances (called waivers in the U.S. military) for medical problems has also been increasing.² Thus, patients like Mr. B who have multiple health concerns and wish to maintain their pilot’s license are not uncommon today.

This article looks at how pilots are medically evaluated and how the standards for medical certification are evolving, allowing pilots who have conditions that would have once grounded them to continue flying.

Evolving Standards and Changing Protocols
Physicians first began to develop protocols for evaluating pilots during World War I, when it became apparent that pilots were crashing their aircraft because of medical and physiologic issues (eg, hypoxia). At first, the approach of these physicians—known as “flight surgeons”—was to develop standards to screen out those who might not be fit to fly; that is, they tried to select individuals who were most likely to perform well when exposed to altitude, acceleration forces, and temperature extremes, and who had acute vision as well as good coordination and quick reflexes. Initially, pilots were expected to have 20/20 vision, normal cardiovascular function, clear minds, and quick reflexes. Consequently, the majority of people were denied medical certification.

Later on, civilian and military agencies developed more sophisticated examination protocols that clarified who was or was not fit to fly. Persons with seizure disorders, severe cardiac problems, or diabetes requiring insulin, for example, were usually not certified because of the potential risk that they might become incapacitated during flight or that their ability to function might degrade. Also excluded were those with conditions such as lung disease, which might decrease tolerance for hypoxia with increasing altitude, or who were using medications that could cloud thinking or slow reflexes such as sedating antihistamines or narcotics. Even age was considered a concern, as it came with adverse changes in cognition, muscle strength, coordination, and tolerance for flight stressors such as hypoxia or acceleration. As treatments improved and thinking about age changed, and after years of study and advocacy by various organizations, those standards and requirements have evolved. For example, under mandate by the Fair Treatment for Experienced Pilots Act, the age limit for civilian commercial pilots was revised in 2007. Whereas pilots were once required to retire at age 60, they can now fly until age 65.

The FAA is guided by federal law—in this case, the Code of Federal Regulations or 14 CFR part 67. If an aviator does not meet specified standards in the law, he or she is technically disqualified, and his or her medical certificate may be denied, suspended, or revoked. However, the FAA allows for Special Issuances, which are valid for a specified period, during which time the pilot must show that he or she can perform the duties authorized by the class of medical certificate applied for without endangering public safety. Standards and exception policies are more strict for those seeking first-class certification than for those seeking second- or third-class certification; in other words, commercial airline pilots (those needing first-class certification) must pass more stringent exams than private pilots. A number of conditions ranging from cardiac problems to psychiatric disorders can disqualify a pilot. Others can disqualify a pilot under specific circumstances. For example, angina pectoris and bipolar disorder would disqualify a pilot, while controlled hypertension or a single episode of renal colic without retained stone would not.

Fit to Fly?
The term “flight surgeon” refers to a physician designated to determine fitness for flying duties (civilian or military) as well as boarded aeromedical specialists. The question of whether a civilian pilot is medically fit to fly is the domain of the AME (see “The Medical Certification Process”). In addition to conducting an examination, these physicians go through a risk-assessment process that considers both the pilot’s physical condition and the type of flying they do. In the early years of aviation, a pilot was a pilot. Today, most countries recognize classes of aviators, ranging from the recreational flyer to the commercial pilot who carries hundreds of passengers.

With this classification system in mind, flight surgeons calculate the risk of a medical condition leading to potential accidents. For instance, a recreational flyer in an ultralight aircraft who suffers a mid-flight syncopal spell is unlikely to cause as much damage as a commercial pilot flying in a Boeing 747 filled with passengers who has such a spell. Arguably, the copilot in the 747 could take the controls, but during critical phases of flight such as landing, especially in bad weather or during an aircraft emergency, suddenly losing half the crew significantly increases the chance for an accident.

When evaluating a pilot’s fitness for flying, flight surgeons often use what is referred to as the “1% rule.” Simplified, this means they will only certify a pilot to fly if there is less than a 1% chance that the individual will have a disabling event caused by their condition during a critical phase of flight such as landing or take off over the course of a year. Obviously, knowing that a pilot has a particular medical problem such as coronary disease or stroke is critical to assessing the risk for an in-flight problem. If one adds in other factors such as age, other medical problems, medications the person is taking and their potential side effects, the effect of fatigue, and whether the pilot flies with another crew member, it can be very difficult or impossible to precisely estimate the risk. This uncertainty has led to conservatism within the industry, meaning that some pilots have not been allowed to fly with illnesses or conditions that might never cause a problem. But that is starting to change.

In addition to calculating the risk that a particular pilot with a particular condition might face, the flight surgeon needs to know the potential steps to take that might reduce or eliminate risks. In the military, this may mean ensuring pilots are fit to successfully operate a jet while tolerating acceleration forces up to nine times the force of gravity. On the civilian side, it could mean understanding that a pilot with a diagnosis of ADHD may have cognitive deficits that could impact judgment and decision-making, although he or she may look healthy and feel well on methylphenidate.

Acknowledging the difficulty of predicting risk, flight surgeons and aeromedical organizations have worked hard to collect data on how pilots with diseases or health concerns have performed during flight. They have used that information to justify relaxing the limitations for some conditions. One example is mitral valve prolapse (MVP). The U.S. Air Force followed individuals with MVP for a number of years and found that most could fly without adverse outcomes.³ In a similar vein, the FAA has recently opened the door to some flyers who are on certain antidepressants (SSRIs), allowing them to resume flying under very tight observation rules. Despite many years of study and data collection, however, we still have gaps in our knowledge base. For that reason, flight surgeons are often forced to use data about the nonflying population to make their decisions about whether a pilot is medically fit to fly.

The Flight Exam
When examining a pilot, a physician must assess whether the individual meets specified standards identified by the FAA or military as necessary for performing flight duties. Pilots who fly commercial aircraft carrying more than 50 passengers must meet stricter standards on urine, vision, blood pressure, hearing, and cardiac tests than those who fly recreationally. In addition to adhering to these standards, they need to pay close attention to issues that are of interest aeromedically. For instance, because of the pressure changes that occur with ascent and descent, Eustachian tube function must be assessed dynamically. The pilot must be able to perform a Valsalva maneuver while the physician observes the tympanic membrane move. The neurologic exam must ensure there are no equilibrium defects. The flight surgeon must understand how to look for potential ophthalmologic conditions beyond visual acuity that might affect the pilot’s ability to read instruments or operate the aircraft. When examining the musculoskeletal system, the physician must ensure the pilot will be able to operate controls and get in and out of the aircraft without difficulty. In some aircraft, the pilot must be able to exit through a cockpit window and slide 15 to 20 feet down a rope during an emergency evacuation.

Working with pilots poses special challenges to physicians. Pilots tend to view the flight exam warily. They want to keep flying and frequently understate medical issues in order to avoid being grounded. The flight surgeon often must work hard to discover underlying issues. For that reason, physicians may need to be alert to subtle signs. Something seemingly minor, such as use of an agent for erectile dysfunction, should lead the examiner to ask whether this indicates a more serious vascular problem such as coronary or cerebrovascular disease, which raises the risk for sudden incapacitation. Also, it’s important that the physician can “speak airplane” and seek to understand the pilot’s point of view. (Some of the best “flight docs” are often pilots themselves.) Encounters tend to be far more productive when there is a good relationship between the pilot and physician. If the physician can convince the pilot that it’s better to address health problems up front, he or she can guide the aviator through some of the toughest waiver procedures in the shortest time possible.

Common Concerns
Several common medical conditions require special evaluations and submissions of waivers or Special Issuance applications. The waiver or Special Issuance process is really just good medicine. The system ensures that the pilot is monitored appropriately, that there have been no significant adverse changes in their health (such as worsening of coronary disease or glaucoma), and that any preventive measures (lowering lipid levels or controlling blood pressure) have been implemented. Although this monitoring may seem onerous at times to pilots, it enables the FAA and military aeromedical agencies to maximize public safety and pilot health simultaneously. An added bonus is the epidemiologic data collected on flyers with various medical conditions, which will be important in determining risk for other pilots in the future. Obstructive sleep apnea (OSA) is an increasingly common condition that requires a waiver or Special Issuance as part of the medical certification process, as it may cause pilots to become easily fatigued or fall asleep during flight operations. Identifying pilots who are at risk for OSA but who may not admit they have it requires the examiner to look for risk factors such as obesity, larger neck size, history of morning headaches, and daytime drowsiness. A sleep study also may be required if they are found to have increased risk factors. Given a diagnosis of OSA, the FAA will want to see that the condition has been successfully treated (eg, with CPAP). The AME will also encourage the patient to reduce his risk by losing weight.

Pilots with atherosclerotic coronary disease must undergo appropriate testing and interventions to prove that their disease is under control and that there is minimal risk for in-flight incapacitation or return of symptoms (ie, angina, dysrhythmia) that might interfere with their ability to perform flight duties. Return to flying after a coronary bypass requires an appropriate waiting period (usually six months), demonstration of normal cardiac function with exercise (a treadmill test), and evidence that the pilot is addressing any modifiable risk factors (obesity, hypercholesterolemia, or hypertension) aggressively and successfully.

If a pilot has suffered a stroke, the concern is for control of risk factors, stroke recurrence, and possible post-stroke sequelae. Typically, a two-year observation period, during which the pilot does not fly, is required even if he or she has fully recovered and has a normal examination. This is because the FAA relies on population data, which indicate that the highest risk of recurrence is during the two years post-event, although this varies with individual risk factors and stroke etiology. Some patients, such as those with lacunar strokes, may be returned earlier if the antecedent risk factors (eg, hypertension) have been controlled.

Pilots with diabetes who are taking hypoglycemic medications such as sulfonylureas are of concern because of potential for hypoglycemic events with few or no symptoms. This can be a significant problem if the pilot is operating an aircraft alone. Use of phosphodiesterase inhibitors can be problematic because of potential for cardiac electrical conduction effects. With sildafenil, color vision changes are an issue.

Diabetes that requires insulin is a particular concern. It is potentially incapacitating if hypoglycemia becomes severe enough, and its complications such as retinal disease can subtly affect pilot performance. For those with type 1 diabetes, returning to flying is a highly controlled process. It is currently an option only for recreational pilots. In such cases, pilots must show adequate control and lack of significant secondary complications such as retinopathy or proteinuria. They also must pass appropriate screening for potential coronary disease including treadmill testing if they are older than 40 years of age.

Although those conditions clearly put pilots at risk, flight surgeons need to be aware that common and/or minor problems also could affect a pilot’s ability to fly safely. For example, even something as seemingly benign as GERD or irritable bowel syndrome may become severely distracting at altitude, given expansion of gas within the GI tract.

Conclusion
The FAA and other aeromedical authorities are concerned about the safety of both pilots and the public. Pilots and physicians, even those who are not flight surgeons, share the responsibility for addressing medical issues in the best way possible in order to limit risk. Conversely, because experienced pilots are safer pilots, it is important not to unnecessarily ground those with conditions that are adequately managed and do not have significant potential to affect their performance. Physicians who are not flight surgeons who see pilots as patients should consider consulting with a flight surgeon prior to embarking on diagnostic and therapeutic interventions, as some diagnoses, procedures, and medications may be less likely to affect the pilot’s flying career than others.

All providers and pilots need to do their best to understand the aerospace environment and the challenges it presents to humans. Because pilots want to keep flying, flight docs need to establish good a relationship with each pilot patient. By encouraging pilots to raise health concerns, they can address them early and keep their pilot patients flying as long as possible and as safely as possible. MM

Lawrence Steinkraus is an assistant professor of preventive medicine at Mayo Clinic. His expertise includes aeromedical evacuation, the aging aviator, chronic illnesses in flyers, and the effects of altitude on patients and flyers.
 

References
1. Federal Aviation Administration, U.S. Civil Airmen Statistics. Average Age of Active Pilots by Category. Available at: www.faa.gov/data_research/aviation_data_statistics/civil_airmen_statistics/2008/. Accessed May 19, 2011.
2. Jordan JL. Help? All hands needed to solve conundrum. The Federal Air Surgeon’s Column. Federal Aviation Administration. Available at: www.faa.gov/library/reports/medical/fasmb/editorials_jj/conundrum/. Accessed May 19, 2011.
3. Osswald SS, Gaffney FA, Kruyer WB, Pickard JS, Jackson WG. Military aviators with mitral valve prolapse: long-term follow-up and aeromedical endpoints. Aviat Space Environ Med. 2007;78(9):845-51.