For pilots and aircrew there is no such thing as ‘just a cold’. A viral infection affecting breathing, concentration and energy levels is a strong reason to ground yourself. You should also know that some cold medications are an aviation hazard in themselves.
Take off with a headache, fever, chills and blocked nose or ears and they could become the least of your problems. Even a minor viral infection can lead to dulled concentration, intense pain and spatial disorientation even at lower altitudes, any one of which can cause you to crash your aircraft.
It’s also important to realise that some over-the-counter and prescription medications for colds and flu can affect your performance.
Why do colds matter?
Simple “head colds” can impair performance more than most people realise. These tiny viruses can cause severe problems in the ears and sinuses, all of which can be incapacitating if people continue to fly.
Many other viruses cause symptoms similar to those of the common cold but can become much more severe. These can extend to an ongoing cough, fever, breathlessness or pneumonia. Around 80% of bronchitis cases with fever, cough and heavy phlegm are caused by viruses. Don’t underestimate how much this “just a virus” can impact your ability to fly safely.
Medicines and incapacitation
Just because a medication is available over the counter doesn’t mean it is automatically safe in aviation.
A particular drug to be aware of is codeine. Since 2018, pain relief and cough and cold medicines containing codeine have only been available with a doctor’s prescription. This is because codeine is converted into morphine by the body and can impair performance in a safety sensitive environment.
If you’re a pilot, engineer, air traffic controller or in any other safety sensitive aviation position, you should not take products containing codeine without consulting a doctor.
Allergy to plant pollens, known as hay fever, can produce similar symptoms to a cold. The cause doesn’t matter. If your ears are blocked and you are feeling blunt, it is not a day for flying, no matter how blue the sky.
Hay fever can usually be treated with antihistamines or decongestants, but antihistamines can cause drowsiness, which is a ground for grounding in itself.
For more information check the CASA website for a list of approved, hazardous and prohibited medications.
Remember, if you’re not sure, to consult your DAME.
There is an excellent book I would recommend for all flight crew, titled, ‘Human Factors for Pilots’, by Roger G. Green, Helen Muir, et al.
On page 11, it discusses at paragraph 1a.5 “Entrapped Gas and Barotrauma . . . One of the consequences of ascent to altitude is the application of Boyle’s Law . . .”
On page 12, continuing with paragraph 1a.5, it discusses “Middle Ear . . . The middle ear is an air filled cavity (connected) with the nose and throat via the Eustachian tube. The walls of the Eustachian tube are soft and the nasal end acts as a flap valve. This allows expanding gas in the middle ear cavity to vent on ascent but on descent, with an increase in ambient pressure, this flap valve can stop air from returning to the middle ear to equalize the air pressure. This failure to restore correct pressure (equilibrium) inside the the middle ear results in distortion of the ear drum giving rise to pain and injury known as otic barotrauma.”
Then read the paragraph under the title, “Sinuses”, where it states, “In a very similar manner to the ears the sinuses can vent gas more easily on ascent than descent, and sinus barotrauma may occur as a result. This is especially true whilst the individual is suffering from the symptoms of cold or flu . . . For this reason aircrew with a cold or flu (updated that to COVID, too) must avoid flying whilst symptoms persist. Failure to do so can result in barotrauma . . . ”
Aircrew should learn how to perform a “Valsalva maneuver” to facilitate the equalization of air pressure. On descent, in an unpressurised aircraft descend at 500 feet per minute. In a pressurised aircraft, the aircrew should take manual control of the Cabin Altitude Controller, during descent, and “descend the Cabin at 500 feet per minute to reduce inner ear and sinus discomfort, which could become incapacitating, which could result in an aircraft accident.
The aforementioned would be the practical application of theory and information you learned to pass your various licencing exams.
Lastly, when I was overseas, flying in China, as a captain of Boeing 737-800 and 737-700 aircraft, my Chinese crew would receive a monetary penalty (fined) by their airline employer for calling in “sick” or to get proper Crew Rest required by CAAC Regulations. Thus, constantly flying with sick crew, made me sick. The airline management tried to fine me only once, contrary to my contract. So, to spare my Chinese crew from being fined, I told them that I would refuse to fly with them, making it my fault, so they would not be fined or penalised by their airline employer. The lesson in that is, you always have to protect your own health and look after your crew, because nobody else will.