Threading the Risk Needle

Why the FAA's temporary move to restrict passengers from electric airplanes is prudent and smart.

UPS DC-8

UPS DC-8

A UPS DC-8 destroyed by a lithium battery fire.

When I turned 15 and started taking flying lessons, my dad gave me a copy of one of the true bibles of piloting technique: “Aerodynamics for Naval Aviators.” First published in 1960, it remains the definitive text on applied aerodynamics for pilots — and at 15, I could barely understand a word of it. It introduced me to concepts such as L/D max, laminar flow, Reynolds number and so on – and it may as well have been written in Latin. I read it, but I didn’t understand it.

When I reread the book years later, I realized it wasn’t nearly as incomprehensible as I thought as a teenager with a scant few hours in a J-3 Cub in my logbook. It even contains some humor (which I totally missed on my first read-through), such as when the author discusses the concept of airspeed and angle of attack as they relate to glider pilots and “flameout enthusiasts.” I’m not sure how long such an enthusiast would last in Naval flight school, but I’m guessing it wouldn’t be more than a few days.

One theory the book introduces is the idea that great pilots know the importance of “threading the needle.” I’d call it the Goldilocks Principle. It’s the notion that we don’t want too little or too much of anything in flying. We don’t want to be too slow on approach, but we also don’t want to be too fast. We don’t want to bank too steeply in the traffic pattern, but we don’t want our turns to be too shallow either. We don’t want to go below glideslope on an ILS, but we don’t want to go above it.

I recently thought of this principle and how it applies to the FAA’s mission of improving aviation safety, specifically with regard to future electric airplanes. The market for battery-powered aircraft is in its earliest stages, but as battery technology improves there’s no question that aircraft manufacturers will seek to build and sell electric airplanes here. It will be up to the FAA in large measure to ensure these new types of airplanes are safe.

The biggest risks are battery fire or explosion and depletion of battery charge while still in flight and miles from a suitable landing spot (the electric equivalent of a flameout enthusiast). To address the first concern, the FAA has proposed prohibiting electric aircraft from carrying passengers. For some in the general aviation community this is a totally unfathomable suggestion. After all, what's the point of owning an electric airplane if you can't take people for rides?

The FAA understands this. It has reiterated that the proposed restrictions, which besides a prohibition on carrying passengers also include restrictions on flying over congested areas or operating at night, are temporary. But the fact is, the burden largely falls on the FAA to thread the risk needle to ensure that electric airplanes thrive in the market, yes, but not at the expense of safety.

It's a delicate balancing act that will require some more study of lithium battery dangers before signing off on the sale and operation of electric airplanes in the United States. After all, we don't want a repeat of the lithium battery fires that grounded the worldwide Boeing 787 fleet last year. We just have to trust that the FAA means what it says about the transitory nature of the electric airplane passenger prohibition.

And really, this is a good news story. The FAA realizes that electric airplanes are coming, and it’s preparing for their arrival. What's not to like about that?

For more on the latest developments in electric flight — some of which might surprise you — see our feature story "Electric Future" in the April issue of Flying or read it online here.

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