The relatively recent development of aviation over the last 100 years requires that the branch of medicine supporting this activity be similarly young. Yet the history of flight medicine remains full of amazing anecdotes and intriguing characters. As flight transitioned from an experimental hobby by a small group of unusual personalities to a huge regulated industry demanded by travelers and military powers, the field of aviation medicine evolved in parallel.
Human physiology has its limitations. Aviation exposes human beings to a variety of environmental preconditions that the human body has no natural ability to counter. In this way, as aeronautical science and engineering slowly evolved, an understanding of human physiologic response and the development of life support equipment to counter these risks remained one small step behind. Later, as atmospheric aviation progressed to exploration of outer space, a similar process took place. Primarily a form of occupational (or environmental) medicine, the field of Aerospace Medicine has become a highly specialized, fascinating medical field.
Historians often debate how world events unfold. Some contend that events are ‘pulled’ along by remarkable individuals who shape the world’s future- the Alexanders, Casears, and Napoleons of the world. Others argue that social and environmental preconditions form a world in which events are inevitable. The story of aviation, much like the greater human narrative likely proceeds from a combination of both influencing factors. We will look at the preconditions that led to the development of this fascinating medical specialty. And also catalogue the biographies of the remarkable personalities who took advantage of a new, dynamic technology; using their genius or resolve to become true pioneers in aerospace.
Although man’s fascination with flight likely predates recorded history, the ability to reliably and safely travel by air had to patiently await for human science and technology to catch up with desire. This would not occur until the 18th century as lighter-than-air balloons began to proliferate. Prior to this time period, the only medical activity reasonably called ‘Aerospace Medicine’ was treatment of injuries incurred from falls suffered by men with cloth bird wings or other homemade flying devices. Aerospace environmental exposures could only be theoretically conceived, as they had not been empirically observed. Flight remained in the realm of science fiction. One of the first documented recognitions of hypoxia was made by the Spanish priest, Father Jose de Acosta. In his Historia natural y moral de las Indias, which was published in 1600, Acosta recorded a constellation of symptoms (presumed to be hypoxia) affecting the Spanish and their animals as they ascended the Andes Mountains.1
Many of the physical laws and principles that would ultimately allow humans the ability to imagine and later invent technologies to fly were first discovered by a variety of scientists throughout the early and late Renaissance. This team of Noble Prize-worthy scientists and philosophers came from a variety of time periods, nations, and academic disciplines. Some of these names should conjure up memories of physics or chemistry class to anyone with a high school education. Scientists such as Newton, Boyle, Lavoisier, Priestly, Charles (first described case of barotitis), Gay-Lussac, Valsalva, Henry, Dalton, and Cavendish had to unlock the various natural laws of our universe before aviation could become a reality.
The year 1783 marked the official entry of lighter-than-air balloon flights into the history of aviation. Competitions between hot air balloons, developed by Joseph-Michel Montgolfier and his brother Jacque-Étienne, and another hydrogen gas variant promoted a rapid proliferation of noteworthy aeronautical feats by balloon. The Montgolfier brothers claimed the first flight with living organisms (a sheep, duck, and rooster) and later that year the first manned flight. On 21 November 1783, the first free flight of a lighter-than-air Montgolfier hot air balloon flew to an altitude of approximately of 3,000 feet (910 meters) over Paris for about 25 minutes. One of the passengers of this first manned flight, Jean-François Pilâtre de Rozier, would tragically also be one of the first aeronautical fatalities. He died with another Frenchman in a 1785 balloon crash while attempting to cross the English Channel.2 Although hot air technology maintains these noteworthy firsts, ultimately, hydrogen gas was used for a majority of other later accomplishments by balloons.
Medical professionals immediately realized the fascinating research opportunities introduced by flight. British physician John Sheldon flew with Jean-Pierre Blanchard, an early pioneer in hydrogen gas balloons, in 1784 attempting to gather physiologic data in-flight. Later, Boston physician John Jeffries also flew in balloons in order to catalogue physiologic responses to flight. Although he was born in Boston and attended Harvard College, John Jeffries maintained British loyalist sentiments during the Revolutionary War. He served as Surgeon General of British Forces in North America 1776-1780. Following the war, Jeffries became fascinated in the baloonomania capturing the public. In 1785, he accompanied Blanchard on the first flight across the English Channel. He later described his flights and experiments in a book called A Narrative of the Two Aerial Voyages, which was published in 1786.3
In a serendipitous twist of historical coincidence, balloonist Jean-Pierre Blanchard met American forefather and physician, Dr Benjamin Rush. Rush had requested that Blanchard measure heart rate at the maximum altitude reached, which he did. The experiment determined that Blanchard’s heart rate averaged 4 beats more in a minute compared to his resting ground heart rate, which Rush contributed to the “pleasure of sailing in the air in a balloon“.4 Interestingly, one of the first physiologic changes when exposed to relative hypoxia is an increase in heart rate. Dr Rush, who was the only physician to sign the U.S. Constitution, went on to keenly predict that “the time may come when this mode of sailing (ballooning) will be employed…with as much safety as sailing upon the water, and with much more advantage.” Blanchard is also credited as receiving the first American passport and delivering the first airmail, both directly from George Washington himself.
As lighter-than-air flight rapidly progressed and gliders also rose on the scene, humans began to increasingly push the limits of the environmental envelope. Exposures to higher and higher altitudes for longer and longer durations slowly increased understanding (sometimes with disastrous consequences) of medical conditions such as hypoxia, decompression sickness, hypothermia, frostbite, and cosmic radiation exposure.
The 19th century led to continuous progress in scientific understanding. It is no surprise that the application of the scientific method accepted to by fields in the physical sciences was first used in the study of medicine during this century. No individual had a greater impact on the incorporation of experimentation and scientific principles in medicine than French physiologist, Dr Claude Bernard (1813-1878). His scientific feats were extraordinary in scope and large in number. Many of his rigorous rules for the application of scientific ideals remain as true today as when he wrote them over a hundred years ago.
Using objective scientific experimentation instead of conventional wisdom and tradition, Dr Bernard discovered the physiologic functions of multiple organ systems and first coined the term now known as homeostasis. In 1865 he published a discourse on the scientific method, which he titled An Introduction to the Study of Experimental Medicine. Many of the themes familiar to any modern day scientific researcher were first introduced by Bernard in this publication. For example, Bernard was the first to recommend blinding an experiment’s participants. His work on the effects of carbon dioxide, oxygen, and hemoglobin greatly assisted those first studying flight physiology. With the groundwork set for scientific evidence-based medicine, all of medicine entered a Renaissance of rapidly expanding knowledge. The fledgling specialty of Aviation Medicine would benefit in kind.
Paul Bert was a French physiologist and protege of Claude Bernard. He acquired doctorates in medicine and science in the 1860’s, later introducing vast amounts of information into the new field of flight physiology, which has earned him the epithet of ‘Father of Aviation Medicine’. Dr Bert was very interested in the effects of altitude on human physiology and conducted 100’s of experiments to research his hypotheses. Not content with experimenting solely with balloonists, he developed the first hypobaric chamber, which was able to simulate altitudes up to 36,000 feet. He experimented with animals to determine the minimum required partial pressure of oxygen in circulating blood. Using the results from these experiments, he came to the conclusion that the use of supplemental oxygen in high altitude balloon travel was necessary, and fervently urged operators to do so. He discovered oxygen toxicity. Ultimately, Dr Bert compiled all of his research into a simple book titled La Pression Barometrique (Barometric Pressure), which was published in 1878. This book would form much of the early foundation for the budding discipline of Aviation Medicine.5
In 1903, two obscure bicycle mechanics from Dayton, Ohio would forever change the world. In that year, brothers Orville and Wilbur Wright demonstrated controlled heavier-than-air flight on the beaches of Kitty Hawk, North Carolina. Modern aviation had begun. 1908 would prove a tragic year for aviation as the first fatality among heavier-than-air flight would take the life of a young Army lieutenant, Thomas Selfridge. Although a formal process for mishap investigation did not yet exist at this early stage of aviation, a precedent was now set to conduct thorough analyses of contributory or causal factors to prevent future accidents and improve aviation safety. As this process matured, aviation medical professionals will prove valuable assets serving as medical consultants and human factors experts.
It wasn’t long after Kitty Hawk, that the War Department (predecessor to the Department of Defense) became interested in aviation for purposes of national security and military operations. As infantry soldiers and sailors transformed themselves into pilots of flying machines, European militaries led the way in setting medical standards for aircrew. The Germans were the first to develop a minimal set of aeromedical standards in 1910, which were soon imitated by the Italians, the British, and the French. The United States followed this trend publishing instructions for aviation physical examinations in 1912 and then actual aeromedical standards in 1916. Much of the medical operations in early military aviation was guided by then Lt Col (later ret. Brig. General) Theodore Lyster (1875-1933). The book Air Service Medical published by the War Department in 1919 was likely written by Dr Lyster and his colleagues Dr Isaac H. Jones and Dr Eugene R. Lewis. This book served as the earliest military aviation medicine textbook.6
Brig Gen Theodore Lyster is the only possible competitor that Paul Bert has for the ‘Father of Aviation Medicine’ epithet. In addition to his efforts behind Air Service Medical, he served as Chief Surgeon of the Army’s Aviation Section during WWI, emphasized the importance of medical standards for pilots as a significant factor affecting flight safety, and created the role of flight surgeon in military flying units. Although he may not have been the first to coin the term ‘flight surgeon’, it was Lyster that really developed the concept. He assigned these military physicians to individual flying units and deployed them with their units rather than the larger medical teams. Gen Lyster also established the Air Service Medical Research Laboratory in Long Island, NY. This facility allowed the military to considerably increase medical research studies in pilots, which were later catalogued in Air Service Medical. Later after retiring to civilian life, Dr Lyster would serve as the medical examiner for the FAA’s predecessor, the U.S. Department of Commerce. In this role, he also organized the first issuing of licenses to civilian commercial aviators.
Dr Lyster chose otologists Isaac H. Jones and Eugene R. Lewis to assist in the expansion of aviation medicine and the opening of medical examination centers for pilots. Both doctors were adamant that these new aviation medical specialists fly regularly to better understand the physiologic consequences of flight. Jones was an especially strong advocate of the mission of the flight surgeon in keeping pilots fit to continue flying duties. He constantly campaigned against the commonly held belief among pilots at that time that flight surgeons only wished to take their wings.
It is uncertain who first created the term ‘flight surgeon’. The Jeffrey R. Davis’ Fundamentals of Aerospace Medicine textbook contends that Eugene Lewis coined the title. Others have given the credit to Isaac H. Jones previously, but this has been challenged by others. Less contentious among military historians is who was the first flight surgeon. Capt Robert J. Hunter M.D. was ordered along with 3 other physicians to report to an aviation school on 8 May 1918. Their orders did not originally contain the words ‘flight surgeon’, but were later revised to include this verbiage stating “amended so as to have the officers report in person to the Commanding Officers at the places specified for duties as Flight Surgeons.”7 In this role, these three physicians were tasked to ensure that military personnel selected as aircrew maintained a fitness to fly. As they developed the roles and responsibilities of the flight surgeon, they also provided early insights into accident prevention, safety improvements, and investigated aircraft crashes. Capt Robert J. Hunter reported to duty on 13 May 1918, two days before his colleagues. He was the first American flight surgeon.
As new records continued to be broken during the interwar barnstorming era, the desire to fly longer, faster, and higher led to novel ideas to support the fragile human operator of the machine. A separate post will discuss the evolution of aircrew flight equipment (AFE) also known as life support.
Aviation medicine research was figuratively and literally abandoned following WWI. A few notable achievements, however, did arise from this period. In 1921, Dr Raymond E. Longacre developed a set of personality criteria that was used to screen and select candidates for flight training. Put into use in 1935, the Mashburn Complex Coordinator, developed by Neely Mashburn, was an apparatus used before and during World War II for aircrew selection. This device measured users’ abilities to make coordinated movements with airplane controls after being presented with a number of challenging visual stimuli. The SAM Complex Coordinator essentially replaced the Mashburn variant during WWII. Throughout the late 1920’s and early 1930’s, after years of both in-flight experience and time spent using barany chairs, Col William Ocker teamed with Lt Carl Crane and Dr David Meyers to more fully understand pilots’ predisposition for disorientation during flight. Ocker, often considered the ‘Father of Instrument Flying’ and Lt Carl Crane published their seminal work Blind Flight in Theory and Practice in 1936. Lastly, two of the most noteworthy names in aviation medicine saw their careers take off during this time period – Harry G. Armstrong gaining his M.D. from University of Louisville in 1925 and Louis H. Bauer serving as Commandant of the School of Aviation Medicine between 1919 and 1925.
Although his contributions to aviation medicine in the United States’ Armed Forces were significant, there are few people who have done more to advance civilian aviation medicine than Dr Louis Hopewell Bauer. After graduating from college and medical school at Harvard, Dr Bauer began his career in the in the Army Medical Corps. His military career was highly successful as he served as Director of the Medical Research Laboratory after WWI, helped to establish the Army School of Aviation Medicine for flight surgeons in 1922, and served as commandant of the school for 6 years. In 1926, with the authority of the Surgeon General, Dr Bauer published a landmark textbook simply titled Aviation Medicine. Later that same year, Calvin Coolidge signed the Air Commerce Act of1926, which established federal guidance and regulations for aviation. Bauer had become so well known in the field of aviation medicine that he was tapped for an early release from the military in order to serve as Director of the Medical Service in the Aeronautics Branch of the Department of Commerce. The Aeronautics Branch later morphed into the Bureau of Air Commerce then the Civil Aeronautics Authority and finally became the Federal Aviation Agency in 1958 assuming the name Federal Aviation Administration in 1966.
Bauer’s first task in the position of Director of Medical Service for all American civilian aviation was to develop the first medical standards for private and commercial pilots and aircrew. Section 66 of the Air Commerce Regulations were officially published and went into effect on 31 Dec 1926. These medical standards listed specific physical standards for three classes of pilots (private, industrial, and transport) and also described a process for granting waivers for the standards. To enforce his medical standards, Bauer used aviation medical examiners (AME’s), which is the title FAA flight medicine doctors still use today.
On 15 Dec 1928, Dr Bauer and 29 other Aviation Medical Examiners formed an academic organization initially called the ‘Aerial Medical Association’, which changed names to the ‘Aero Medical Association of the United States‘ within a few weeks. Louis Bauer held the title of temporary chairman until the first annual meeting. It was no surprise when Dr Bauer was officially elected President of the organization. Although he resigned the position in Nov 1930, it was under his leadership that The Journal of Aviation Medicine was created. The legacy of these three achievements cannot be understated. AME’s continue to ensure that the nation’s civilian pilots and aircrew remain fit for flight. The Aerospace Medical Association is the leading international academic organization in aerospace medicine, and it’s journal, now known as the Journal of Aerospace Medicine and Human Performance remains the most prominent science and research journal in the field.
In addition to all that has already been stated above, Dr Bauer received numerous awards throughout his career, was pivotal in establishing aviation medicine (later expanded to aerospace medicine) as a board certification, and even served as President of the American Medical Association (AMA) from 1952-53.
Hap Arnold, Malcolm Grow, Dr Harry Armstrong, Col John Stapp, the advent of the air ambulance, and many more
1. J. de Acosta: Efecto estraño que hace en ciertas terras de Indios el aire, coviento que corre. In his: Historia natural y moral de las indias. Sevilla, Juan de Léon, 1590. Volume 3, chapter 9. English translation in 1604: Natural and Moral History of the Indies.
2. Beischer, DE; Fregly, AR (1962). Animals and man in space. A chronology and annotated bibliography through the year 1960. US Naval School of Aviation Medicine. ONR TR ACR-64 (AD0272581).
3. A narrative of the two aerial voyages of Doctor Jeffries with Mons. Blanchard; with meteorological observations and remarks. The first voyage, on the thirtieth of November, 1784, from London into Kent: the second, on the seventh of January, 1785, from England into France – Jeffries, John, 1745-1819.
4. Rush, Benjamin. Benjamin Rush’s Lectures on the Mind.
5. Bert, Paul (1943) [First published in French in 1878]. Barometric pressure: Researches in Experimental Physiology. Columbus, OH: College Book Company. Translated by: Hitchcock, Mary Alice; Hitchcock, Fred A.
6. War Department. Air Service Medical. 1919
7. Hunter BJ. The first flight surgeon. Milit. Surg. 1942; 91:349-353.
8. William C. Ocker & Carl J. Crane. Blind Flight in Theory and Practice. Naylor Company, 1932.
9. Original Air Commerce Regulations for the Aeronautics Branch of the Department of Commerce, published 31 Dec 1926.