Dec 27 2021

Fatigue a Stealthy Killer Posted 2 years 332 days ago ago by Admin

Have you ever been so tired flying at night or early morning that, thinking back on it, you could not remember the takeoff? As an air medical pilot in the early days in Houston and San Diego, I can raise my hand and say, “I have.” And why was that? The answer: Fatigue.

The International Civil Aviation Organization, ICAO’s, definition of fatigue is this: “A physiological state of reduced mental or physical performance capability, resulting from sleep loss or extended wakefulness, that can impair a crew member's alertness and ability to safely operate an aircraft or to perform safety related duties.”

An article posted by Aerossurance aviation consultants on 26 September 2020 titled “Fatal Fatigue: U.S. Night Air Ambulance Helicopter Loss of Control – In-flight Accident (Air Methods AS350B2 N127LN, Wisconsin)” describes how the pilot and two medical personnel aboard were killed in the crash. The helicopter, operating as “Ascension Spirit Air”, was on a night repositioning flight after two prior inter-hospital patient transfer flights with a refueling stop. The U.S. National Transportation Safety Board (NTSB) issued a simple probable cause: The pilot’s loss of helicopter control as a result of fatigue during cruise flight at night.

Addressing fatigue is a big issue in our nation’s airlines, especially following the Colgan Air crash which occurred on 12 February 2009. The aircraft involved was a Bombardier Q400 turboprop that entered an aerodynamic stall perpetrated by the pilot flying, from which it did not recover, and crashed into a house in Clarence Center, New York, killing all 49 passengers and crew on board.

The National Transportation Safety Board (NTSB) found the probable cause to be the pilots' inappropriate response to the stall warnings in a stall they inadvertently caused then mishandled in the attempted recovery. Fatigue was noted to be a contributing factor in the crash. Families of the accident victims lobbied the U.S. Congress to enact more stringent duty-time requirements for regional carriers to avoid similar accidents due to pilot fatigue.

I had the opportunity to attend the American Airlines Training Academy and sit in on several CRM training courses. Crew fatigue was front-and-center in each presentation I attended. I was surprised to learn that the airline takes crew fatigue so seriously they pay their crew members $1,000 not to come in if they are tired or fatigued.

Research has shown that loss of sleep can be as detrimental to judgment and reaction time similar to the effects alcohol has on the human body. In a study published in the BMJ (British) peer-reviewed journal Occupational and Environmental Medicine, researchers in Australia and New Zealand reported that sleep deprivation can have some of the same hazardous effects as being drunk. They wrote: “People who drive after being awake for 17 to 19 hours performed worse than those with a blood alcohol level of .05 percent.”  

In addition, their findings demonstrated that getting less than 6 hours sleep a night can affect coordination, reaction time, and judgment creating "A very serious risk."  If one goes 24 hours without sleep, their judgment and reaction time are similar to being legally drunk.

Sleep research has shown that a person’s Circadian Rhythm (the 24-hour internal clock in our brain that regulates cycles of alertness and sleepiness by responding to light changes in our environment and  sometimes referred to as one’s Body Clock) is at its lowest ebb between 4-6 a.m. in the morning. This fact is something you should be aware of when you take that early-morning flight. My early morning flight combined with lack of rest most likely explains why I could not remember the takeoff on that San Diego moonless night in 1980 while being made to work 48-hour shifts at UCSD Medical Center. 

Another contributing factor to my state of fatigue? We were made to lift off in 5 minutes or less, day or night. Each morning following a night shift, the medical director at the time would check the time cards in the dispatch center checking to see if we were off within that 5-minute window. If not, he would question us as to why we were not airborne within those 5 minutes. 

Things have changed dramatically since then, but that is just how it was in the early days of helicopter EMS when we were striving to prove the helicopter air ambulance concept. It’s one of several reasons I wrote my first book entitled, The Golden Hour. It was my way to shine a spotlight on the fatigue problem to anyone who would listen in my personal effort to hopefully enact change. The change I was hoping for, but never saw in my six years as a HEMS pilot, was to work 12-hour shifts like our six flight nurses did. I would often argue that if a doctor, nurse or paramedic are dog-tired they possibly could make a mistake and kill the patient. On the other hand, if the pilot is dog-tired there’s the deadly potential he’ll kill everyone on board, which might include a patient.

On those late-night/early-morning flights, more often than not the flight nurse on duty would hand me a cup of coffee as we boarded the elevator taking us up to the helipad. I guess when you think about it, she had a vested interest in keeping me awake. I literally had her life and the life of the doctor and patient in my sleepy hands.

Another consideration if suddenly jolted out of a deep sleep, which would happen often by a late-night phone call by dispatch, is something called sleep inertia. Sleep inertia is that tired, heavy feeling we feel after coming out of a deep sleep. Typically, sleep inertia disappears after about 30 minutes, according to a 2019 study. In fact, sleep inertia can sometimes disappear within 15 minutes. However, what some scientists call a “full recovery” takes about an hour to achieve — and it can continue to improve over the course of about two hours. Can you see how sleep inertia would affect a pilot’s ability to operate a helicopter safely especially if awaked from a deep sleep expected to lift off in 5 minutes or less.

So before you take that next flight do a quick assessment. Ask: How much rest have I had? Have I had my required hours of sleep? What time of day is it? Am I within that 4 - 6 a.m. timeframe where my Circadian Rhythm, judgment and reflexes are at their lowest ebb? How long have I been awake? Has it been over 17 hours, 19 hours, or 24 hours? If you answer yes to any of these questions perhaps you shouldn’t take that flight or, if you do, take your time, don’t rush, be aware you are not operating at your peak performance and keep things conservative. Err on the side of caution in any decision you are about to make. Doing so will help ensure you and your passengers make it home safely.

About Randy:
Randy Mains is an author, public speaker, and a CRM/AMRM consultant who works in the helicopter industry after a long career of aviation adventure. He currently serves as chief CRM/AMRM instructor for Oregon Aero. He may be contacted at [email protected].