Sweet Dreams

The issues also apply to general aviation pilots, even though specific FAA regulations may not. For its part, the NTSB is placing special emphasis on the need to study and address the implications of the phenomenon called obstructive sleep apnea (OSA).

OSA is a nighttime sleeping disorder in which the upper airway narrows or collapses during sleep. Affected individual can't breathe, which causes them, at least partially, to wake up. They may not even be aware of what's happening. The disruption can occur hundreds of times nightly, preventing adequate sleep and causing affected individuals to wake up fatigued. People with OSA may have difficulty dealing with challenges and staying awake during the day. Research has shown that people who are obese or snore are more likely to suffer from OSA, and men are more likely to have the affliction than women. Adding to the significance of OSA as an aviation medical issue are studies linking OSA with hypertension, heart disease, heart arrhythmia and increased risk for sudden cardiac death.

In a safety recommendation, the NTSB called on the FAA to modify the application for medical certificates so that it asks whether the applicant has, or has ever had, obstructive sleep apnea or any of the risk factors for OSA. It wants the FAA to find a way to identify those pilots who are at high risk for OSA, and be sure that those who already have it or are at high risk for developing it are receiving treatment before being granted unrestricted medical certification.

The NTSB believes that while an estimated 7% of the U.S. adult population has it, FAA medical records indicate that as few as 0.3% of third-class medical certificate holders have been diagnosed with OSA. As a further contrast, the NTSB notes that the U.S. Air Force indicates 1% of its pilots have OSA.

In August, the Safety Board finished its investigation into the February 13, 2008, incident involving a Mesa Airlines regional jet flying from Honolulu to Hilo, Hawaii, with two pilots, a flight attendant and 40 passengers on board. During the flight, both pilots fell asleep and the airplane overflew its destination airport, winding up over the ocean. The Bombardier CL-600-2B19 was being operated by Mesa as Go! Flight 1002. The flight crew's communications with ATC during departure from Honolulu had been routine. At about 9:30 a.m., the captain had contacted the Honolulu Control Facility and reported climbing through 11,700 feet to the FL210 cruise altitude. A controller acknowledged this transmission and cleared the flight to proceed direct to the PARIS intersection, near the island of Hawaii. The captain acknowledged the clearance, but the flight didn't change course.

At 9:33 a.m., the controller repeated the clearance. The captain again acknowledged and the flight's track turned toward PARIS. Both pilots later stated that soon after they received this clearance, they inadvertently fell asleep in the cockpit. The captain stated, "Working as hard as we had, we tend to relax." He further stated, "We had gotten back on schedule, it was comfortable in cockpit, the pressure was behind us. The warm Hawaiian sun was blaring in as we went eastbound. I just kind of closed my eyes for a minute, enjoying the sunshine, and dozed off." The first officer said he entered a sleeplike state from which he could "hear what was going on, but could not comprehend or make it click."

At 9:40 a.m., as the flight was crossing the island of Maui, the controller radioed a frequency change, but there was no reply. For the next 18 minutes, the control facility tried fruitlessly to contact the airplane. At 9:51 a.m., the airplane reached the PARIS intersection and the autopilot turned it southeast toward the Hilo VOR. The controller handling the flight asked another controller to try to raise the flight on a different frequency; the other controller tried, but got no reply. Flight 1002 crossed the Hilo VOR and the destination airport, Hilo International. It continued southeast at FL210, crossed the northeast coast of Hawaii and flew out over the open ocean. ATC asked other Go! pilots to try to raise Flight 1002, but they received no reply. In addition, a Continental Airlines flight tried on an emergency frequency, but also was unsuccessful.

Around this time, the first officer woke up. The first officer woke the captain and told him ATC was attempting to contact the flight. At 9:58 a.m., the captain radioed ATC. When the controller asked whether they were experiencing an emergency, the captain reported, "No, we must have missed a handoff or missed a call or something." ATC then gave the flight vectors back to Hilo, where it landed safely.

Investigators reported that the captain told FAA personnel by telephone that radio communications had been lost because the crew had selected an incorrect radio frequency. He subsequently had a discussion with the first officer about whether they should operate the next flight. The pilots agreed that it would be safe for them to do so because they were feeling very alert as a result of the incident. According to company records, they departed Hilo to return to Honolulu on the incident airplane as Flight 1044. During the flight back to Honolulu, the pilots discussed the incident further and decided to remove themselves from duty after landing. Later in the day, the captain wrote a report to the airline about what had happened.

The captain, age 53, has an ATP certificate with type ratings for a number of turboprop and jet regional airliners. He has worked as an airline pilot for more than 20 years. He had 25,000 hours of flight experience, including 8,000 hours as pilot in command in Bombardier regional jets. The captain told investigators that he had never before inadvertently fallen asleep during a flight, but he had intentionally napped in the cockpit during previous flights. The captain's most recent FAA first-class medical certificate had the limitation "must wear corrective lenses while exercising the privileges of this certificate."

The captain described his health as "fair" and stated that he was prone to respiratory illnesses, but hadn't experienced any problems the week before the incident. He reported high blood pressure, and took prescription medication to control it. He stated that he hadn't taken any medications, prescription or nonprescription, that might have affected his performance. The captain was a regular smoker and reported smoking about 25 cigarettes per day.

The captain said he had been feeling "burned out" in recent months. He attributed this to his working conditions, less time off and frequent amendments to his schedule. He said that he had encountered these challenges before, but had recently been finding it more difficult to cope with them. Although he lived in Missouri, he said he had applied for a temporary assignment in Hawaii in search of some relief, but had found the work in Hawaii no easier because he had to fly eight legs per day with few breaks. This made it tough for him to find time during work hours for coffee, eating and smoking cigarettes.

On the two days before the incident, the captain said he was going to sleep by 9 p.m., waking up at 4 a.m., reporting for duty at 5:40 a.m., flying eight legs daily with the incident first officer and going off duty by 3 p.m.

The captain said that he snored loudly at night, and that he had raised the issue with his personal physician two or three months before the incident. The doctor told him to lose weight, eat less salt and relax. He stated that, during his stay in Hawaii, he had lost 15 pounds through exercise and was "sleeping better." After the incident, the captain underwent an evaluation by a sleep medicine specialist---he was diagnosed with severe OSA.

The first officer, age 23, has an FAA first-class medical certificate with no limitations. He described his health as "good" and he said he felt well on the morning of the incident. He stated that he didn't normally take prescription medication and hadn't used any medications in the 72 hours before the incident. He didn't use tobacco. He held a commercial pilot certificate. According to company records, he had 1,250 hours, including 500 hours in the Bombardier jet. The first officer said he wasn't experiencing any stress related to his personal life on the morning of the incident, nor had he experienced any recent changes in his health or personal life.

The first officer told investigators that he had never fallen asleep during a flight before. On the two days before the incident, he had gone to sleep by 10:30 p.m., gotten up by 5 a.m., reported for duty at 5:40 a.m., flew eight legs and got off duty before 3 p.m.

The NTSB determined that the incident's probable cause was the captain and first officer inadvertently falling asleep during the cruise phase of flight. Also contributing were the captain's undiagnosed OSA and the crew's recent work schedules, which included several consecutive days of early-morning start times.

Peter Katz is editor and publisher of NTSB Reporter, an independent monthly update on aircraft accident investigations and other NTSB news. To subscribe, write to: NTSB Reporter, Subscription Dept., P.O. Box 831, White Plains, NY 10602-0831.