Friday, March 29, 2013

Red Eyes Can Signify Dehydration

I was told once in a human factors course that dehydration by as little as two percent has a measurable effect on a person's decision-making ability. The course was generally dull and redundant--I remember entertaining myself by devising and sharing "Buzzword Bingo" cards--but that factoid struck a chord. I don't have a reference to the study that determined that effect, but it's referred to here, and there's more advanced information on pilot dehydration here.

I carry a 750 mL water bottle with me in the cockpit, sometimes bringing an extra litre in the summer, so I never have to ration myself on water--but then I run up against the problem that not all the water my body processes is lost in sweat or water vapour in respiration. European researchers say that the need to urinate enhances the ability to make decisions but another study says the extreme need to urinate reduces cognition and working memory as much as a 0.05% blood alcohol level.

Flying requires decision making and working memory. I heard a pilot today advise ATC that they were landing "with one secured." If I decide to shut down one engine in flight and am thus landing with the power of only one, it would probably be a good decision to delay putting the gear down until I was sure I would not need to overshoot. But despite all the things I might be thinking during that approach, I would need the working memory to remember that I haven't extended the gear yet. And I'd really rather not be landing with my legs crossed.

There are a lot of resources available through Transport Canada and other aviation agencies around the world to help us pilots improve our ability to make safe decisions. We can get information on accidents others have suffered or avoided, information on weather, deicing, aerodynamics, communication, psychology, physiology and ... I don't have time to read it all. I like to think I have the general idea, however.

There's one thing I'm out of touch on, though. How can you call yourself a professional pilot and take people's life into your hands while impaired on recreational drugs? I'm disgusted. Yellowknife is not a big place, and Tindi hires through the ramp, so he wasn't new in town. There were undoubtedly people who knew what Matthew Bromley's job was, when he was flying and what he was smoking. They are irresponsible too.

I still think this anti pot-smoking poster is hilarious, but I want my fellow pilots to be responsible. Their behaviour reflects on me.


Sarah said...

As cannabis becomes more and more like alcohol - legally and socially accepted - we're going to have to come to terms with it. Flying, or driving, while impaired by anything is a horrible thing to do, and deserves to be a crime with serious penalties. Where the boundaries should be, I am not sure. We've apparently decided 8 hours is legally enough for alcohol. Is 24 hours enough for THC? 48? Never?

I read the accident report. The pilot had 10x the level of THC in his blood as would indicate recent, within 6 hours, use. They wanted to retest, but "there was insufficient remaining femoral artery blood". Shudder. This THC level probably means he had a tolerance, built up by frequent habitual use. Probably not the guy I want flying me around, single pilot IFR. I don't understand how people can work themselves into such sad, fatal corners, and take innocent people with them.

YYC Dispatcher said...

Professional pilots are complaining every day about how their profession is being degraded every year with lower salaries and tougher working conditions. I am disgusted as well that other professionals in the industry would have known about this individual's drug use and did nothing to stop him from flying. Innocent people were killed and injured as a result of this pilot's actions. They had an expectation that their pilot wasn't high on pot and would get them safely to their destination.

It will be very interesting to see what civil law suits develop against his estate and against Air Tindi as a result of this investigation. I expect Air Tindi's insurance company will be wanting some of their money back as well.

YYC Dispatcher

GPS_Direct said...

Interesting post - on several fronts.

As you've likley seen, two states (south of the 49th parallel) have legalized cannabis use. The FAA is going to need to come up with some guidelines of some sort, though it will likely take them 10 years.

And, on the point of hydrating, I've experienced both ends of the spectrum. Long, unpressurized flights in dry air at altitude have left me feeling sluggish and behind the airplane (well, more so than normal). Interesting that a study has given me a data point to (somewhat) provide an excuse, lol.

On the other side of the coin, those of us from the deep south enjoy sweet iced tea. Northern states don't know that this doesn't mean trying in vain to stir a single sugar packet into near-frozen liquid... So, on returning from the annual pilgramage to Oshkosh, a stop was planned at an airport with a nearby restaurant chain known to have sweet tea. Several liters of tea later we were were certainly experiencing enhanced decision making as we eyeballed the charts looking for an unplanned stop just 90 minutes into what should have been a 5:00 leg...