Most of us are pretty good about using our preflight checklists before we take to the air, but what about all of the other checklists? When I was working on my instrument ticket, I got a lot better about using my in-flight checklists. In fact, if I fly a plane that doesn't have manufacturer checklists and I can't find any checklists online, then I make my own.Why am I so dogmatic about checklist use? Using checklists takes a lot of the mental load off of flying; you can spend more effort executing the steps of the checklist when you don't have to try to remember them.
To be sure, you should try to be very familiar with your checklists (especially emergency checklists), even to the point that you could perform them from memory, but you shouldn't do it unless you just don't have enough time to pull the list out to check it.
Another benefit to using checklists is that you're less likely to lose your place in your checklist when there's a distraction. One time shortly after I got my private, I was flying into a relatively busy controlled airport and I was going through my descent checklist. Everything was going fine until someone behind me declared an emergency.
I started getting vectored all over the airspace for spacing. Things were very hectic for several minutes, but I wasn't worried; I had everything under control. When things settled down a bit, I started back through my mental descent and landing checklist. The problem was, I started back a few steps past where I stopped. I had missed the mixture.
Well everything went fine during the entire approach, but as I slowed down on rollout and with my power at idle, the mixture was just too lean and the engine sputtered out. Tower called and simply asked, "you gonna be able to get that started." I was already in the process of enriching the mixture and starting the engine so I called back embarassed, "Yessir. Sorry about that."
I was mortified by my awshit! Tower called back and said, "don't worry about it; it happens all the time." I talked to my instructor about it and he said, "don't get too down about it Patrick; people make mistakes, but I hope you learned from it." I still didn't feel very good about it and even telling it now is a little embarrassing.
Well, I did learn from it (and I hope you can learn from me); always use your checklists! Even something as simple as the GUMPS check can be confused by very simple interruptions.
Have fun. Be safe. Happy Piloting.
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© 2008 — , D. Patrick Caldwell, Vice President for Research and Development, Emerald Software Group, LLC
© 2008 — , D. Patrick Caldwell, Vice President for Research and Development, Emerald Software Group, LLC
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If you forget to enrichen the mixture prior to landing and the engine quits on rollout, the mixture was far too lean on entering the traffic pattern to begin with. It should be slowly enrichened throughout the descent; the air is getting thicker, more air molecules are entering the cylinders, and more fuel molecules are necessary to maintain something close to a stoichiometric ratio. The reason you go full rich before landing is not to keep the engine running on rollout, but in case you need to go around. Some flight instructors do their students a disservice by only using the mixture at top of climb and before landing; it really should be adjusted with every change of power and altitude.
ReplyDeleteYour point about always using the checklist is a good one that many more GA pilots should take to heart. Even simple aircraft have enough controls and instruments that its easy to miss something when distracted (and there will *always* be distractions).
Thanks a lot Sam. You're absolutely right about the mixture. I should probably dedicate an entire blog post to mixture, air density, and altitude.
ReplyDeleteTo be sure, I didn't intend to say that the enriched mixture was to keep the engine running on roll out; rather, that the lean mixture caused the engine starvation when I chopped the throttle and the wind quit turning the prop.
Even without a deep understanding of air/fuel mixture, it is still something often overlooked in primary flight training. Almost every checklist I have seen for every plane I've flown has something about adjusting the mixture. You set the mixture before you start, you set the mixture before you taxi, you set the mixture before you run-up. Then, you set it for takeoff, climb, en-route, engine failure, engine fire, descent, landing, etc. Everything has a mixture adjustment.
Using checklists will ensure not only that you have the appropriate mixture during your descent; it will also optimize your fuel consumption and it will increase the longevity of your engine.
But, like I said, the post isn't as much about mixture as it is about checklists. If you have another good example, I'd love to hear it. I've actually started a checklists section and I recently put up another article about checklists vs. "do-lists".