New Tech: Accurate Fuel, Envelope Protection…

The number one reason aircraft end up in the weeds is still lack of fuel to the engine(s); starvation or exhaustion. The gauges on small planes have always been unreliable and estimates are subject to error and “excessive optimism.” I am sure that you, like every other pilot trained, have been counseled repeatedly “never trust your fuel gauges.” And this is for the very good reason that their reliability has been terrible. (and there are easily explainable reasons for the inaccuracy)

One of the many blessings of new aircraft and associated technological advances is the amazing accuracy they demonstrate when fueling (provided you input the new data correctly!) We now often verify a top off to within a tenth of a gallon of the gauge reading. For older aircraft, CiES, an innovative company based in Bend, Oregon, has developed highly accurate, reliable magnetic field fuel quantity sensors STCed for installation in just about every GA aircraft. Their testing data and verification of accuracy and durability is amazingly comprehensive. If you honestly want to manage the #1 risk factor in your flying, installation of accurate fuel gauges is hard to ignore. But how will our industry react to this news?

I can bet many pilots and educators will continue to preach “never trust your fuel gauges.” And though I certainly would agree with that advice if they mean trusting as a single source of data, wouldn’t it be great comfort to finally have an accurate, reliable depiction of acutal fuel on board to compare with a calculated estimate (to filter out gross errors)?  Of course we also know the tragic irony is that despite absolutely accurate fuel readings, pilots will still continue to run out because they can cut their margins even closer (hard to defeat human “ingenuity”). Has anyone out there tried these new units and can offer a testimonial? Even the 1946 bobber in my 7AC Champ is nervous.


Another bit of tech wizardry in modern planes is the “envelope protection” initiative from Garmin and Avidyne built into new airframes (just when SAFE is advocating for pilot “envelope expansion” practice for safety).

I was instructing commercial 720 steep turns for a multi-commercial add-on in a DA-42 and the machine made it clear 50 degree banked turns were “unacceptable” for “normal operations.” The servos (auto pilot off) kept nudging the stick back to level. It took a little digging in the manual to discover the the setting in the G-1000 to disable this feature (continuously operational even with autopilot off). Better guidance from Garmin is here and for Avidyne systems here. Until I learned more I had a “Max-8 MCAS moment.” And even with the control servos disabled the alarms go off to let you know you are “too steep” with aural warnings. It’s a brave new world out there with something to learn everyday. Fly safely (and often).


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Author: David St. George

SAFE Director, Master CFI, 141Chief Instructor, FAA DPE, ATP (ME/SE) Currently flying 135 charter (again)

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