The Slippery Slope Of OSA

A mandatory OSA testing plan of medical certificate applicants was announced by FAA flight surgeon Dr. Fred Tilton. In its efforts to justify the testing, the FAA pointed to NTSB recommen­dations and the Safety Board's accident files. The plan's most vocal critics, AOPA and EAA, found that OSA has never been the probable cause of an aviation accident and has never been demonstrated to adversely affect aviation safety. I found the same thing.

A serious concern is that by requiring mandatory testing for a condition that has no history of accident causation, the FAA starts down a slippery slope that could lead to mandatory testing for numerous other conditions based on bureaucratic whim rather than demonstrable safety impact.

According to the Mayo Clinic, obstructive sleep apnea occurs when your throat muscles intermittently relax and tissue blocks your airway during sleep. It may cause you to wake up. Loud snoring punctuated by periods of silence is a typical characteristic. It's estimated that about 4% of males and 2% of females in the general population are affected, but a study cited by the FAA suggested a 7% overall figure. Alcohol use, smoking and diabetes are known to increase the risk of having OSA; it's not just tied to being overweight or having a large neck circumference.

A Mayo Clinic study found that if you have 20 or more apnea episodes per hour of sleep, causing your blood oxygen level to fall as low as 78%, you're at increased risk of sudden cardiac death during the sleep period, typically including the hours of midnight to 6 a.m. People without sleep apnea die more often from sudden cardiac death between 6 a.m. and noon.

I don't know any pilots who fly between midnight and 6 a.m. while asleep, but I know many who do fly between 6 a.m. and noon while awake. The FAA claims that if your sleep is interrupted because of apnea episodes during the night, you'll be tired during the day. Of course, there are many other things that can interrupt your sleep, from a crying baby, to noisy garbage trucks and low-flying aircraft, and worry about your upcoming FAA medical exam.

Although the FAA claims that OSA is "almost universal" in overweight people with a body mass index (BMI) greater than 40, that's not true according to a study by the University of Texas Health Science Center. In patients who were being evaluated for weight-loss surgery, the incidence didn't enter the range I'd call "almost universal" at 95% until the BMI was greater than 60, which is more than severely obese.

Body Mass Index, or BMI, was created about 100 years ago in Belgium, and is calculated by dividing a person's weight in pounds by their height in inches squared, then multiplying that result by 703. If you're using metric measurements, you don't multiply by 703. It's not a direct measure of body fat, although it's used as if it were. Having a high BMI doesn't automatically mean you have OSA, and having a low BMI doesn't automatically mean you don't have it.

The FAA isn't the only government transportation agency with an OSA fascination. The Federal Motor Carrier Safety Administration (FMSCA) plans for mandatory sleep apnea testing of truck drivers with a BMI of 35 or higher when they renew their commercial driver licenses. If found to have OSA, FMCSA wants drivers to be treated using a continuous positive airway pressure (CPAP) machine. CPAP uses a mask worn during sleep to force air into a person's airway. A CPAP typically costs from $700 to $1,850. An average cost for polysomnogram sleep testing is $2,625, according to a trucking industry source. This testing monitors brain waves, blood oxygen levels, heart rate, eye movement and muscle activity for at least one sleep period and sometimes two. The FAA favors the same testing and CPAP treatment.

The first phase of the Tilton/FAA plan requires testing if your BMI is 40 or more, and if your neck has a circumference of at least 17 inches. Tilton said the trigger point would eventually be lowered to cover anyone who might have OSA. That could be every pilot and controller applicant.

In a fact sheet published to help justify its OSA plan, the FAA points to the NTSB report of an incident from February 13, 2008. Flight 1002 operated by Mesa Airlines was a Bombardier CL-600 with 40 passengers, one flight attendant and two pilots on board. The regional jet took off from Honolulu, Hawaii, at 9:16 a.m. About 9:40, halfway through the flight to General Lyman Field in Hilo, Hawaii, the pilots stopped responding to controllers. Radio contact didn't resume until 18 minutes later. By then, the airplane had overshot Hilo by 26 miles, about three minutes of flying time. The aircraft subsequently landed safely. About three months after the incident, the captain was diagnosed with severe OSA. The first officer didn't have OSA. Both had been working long hours on consecutive days, flying up to eight legs in nine hours and averaging 17 minutes between flights. They didn't have adequate time for breaks, meals or restorative sleep and had to start work at 5:40 a.m., on the three days leading to the incident.

In its fact sheet, the FAA stated that the captain had undiagnosed OSA, but ignored the fact that the first officer fell asleep without having OSA. The FAA also failed to mention that the NTSB Safety recommendation highlighted pilot fatigue caused by shift timing, working a large number of consecutive days, flying a large number of legs during the day and other issues. The FAA failed to mention that the NTSB drafted its recommendation in the context of commercial airline activity. On page six of the August 7, 2009, safety recommendation cited by the FAA, the NTSB states about OSA, "...the NTSB concludes that efforts to identify and treat the disorder in commercial pilots could improve the safety of the traveling public."

In its fact sheet, the FAA said the NTSB database has 34 accidents involving people who had sleep apnea, 32 of which involved fatalities. When I did a search for accident reports referencing sleep apnea, I also came up with 34 returns from the approximately 135,000 reports on file. However, the reports included NTSB speculation that someone may have been "at risk" for sleep apnea, wording that would have alerted the search engine to flag the report. Probable causes of these accidents included flight by non-instrument-rated pilots into IMC, partial engine power loss and encountering a sudden severe crosswind, among others. None was blamed on "sleep apnea."

One of the accident pilots who actually did have sleep apnea reported the condition to the FAA and received a special-issuance medical certificate. According to the NTSB, his accident had nothing to do with sleep apnea. The pilot was on a VFR flight plan for a flight that went from sea-level terrain to mountains in Alaska. Although the weather briefing he received forecast isolated areas of low visibility, the mountain pass he had to traverse was forecast to be VFR in rain showers. The forecast turned out to be wrong; the Cessna T206H crashed into a mountain near Chickaloon, Alaska. The pilot and both passengers were killed. The NTSB determined that the probable cause of the accident was the pilot's continued VFR flight into instrument conditions and subsequent collision with mountainous terrain while maneuvering.

The FAA's fact sheet also claims that the NTSB's database contains 294 incidents involving some type of sleep disorder. My own "sleep" search returned 295 reports. These were quite consistent in having fatigue as the culprit, rather than a medical sleep disorder such as OSA, narcolepsy or insomnia, as might be inferred from the FAA's use of the term "sleep disorder."

One of the fatigue accidents involved a Cessna 172S that struck trees near Land O' Lakes, Fla., shortly before 2 a.m. The FAA-certificated private pilot was a Swiss citizen who worked as a captain of Airbus airplanes for a Swiss airline and had logged more than 13,000 hours. The VFR flight originated at Pensacola, Fla., and was destined for Tampa Executive Airport (VDF), Tampa, Fla.

At 1:49 a.m., Tampa Approach noticed that the airplane had descended below 1,000 feet, 15 miles from the airport. The pilot didn't respond to radio calls. The airplane continued in a gradual descent until radar contact was lost. The NTSB found that during the nine days before the accident, the pilot flew five days of international flights as captain, returning to Zurich three days before the accident. About four hours later, he began a trip as a passenger to Colorado. The day before the accident, the pilot began the three leg flight to Florida in the 172S. He had been awake for about 18 hours at the time of the accident, having stopped only for food and fuel.

The NTSB said that in the days before the accident, the pilot made three crossings of the Atlantic Ocean, each flight crossing six time zones. The NTSB said this disruption to his body's circadian rhy-thm would have hurt his ability to obtain restorative sleep. Add the pilot's extended time awake in the United States, and the result was fatigue. The NTSB didn't raise the subject of sleep apnea, concluding that the pilot's schedule resulted in fatigue that caused him to most likely fall asleep during the initial descent for landing.