The Fallacy of Full Fuel & Full Seats

Most GA airplanes were never designed to simultaneously fill the fuel tanks and the seats with adults. Heck, even the widebody airplane I fly for a major carrier can’t do this. Yet, the misunderstanding of this subject persists to the point where buyers still reject viable options for this very reason.

Let’s take a deeper dive into the subject.

First, one has to realize that both variables (the number of seats and the capacity of the fuel tanks) is often decided upon purely for marketing purposes so that a manufacturer can say, often in the same ad, that their plane will go XYZ miles and that it has a 4, 6, 8, or whatever seating capacity. What they don’t tell you, unless it’s in the little bitty print at the bottom of the page, is that the airplane can’t do these things all at the same time.

Let’s look at a couple of popular 6-seat options.

Take the A36 Bonanza, for example. Let’s pretend we’re looking at a model with a 1300 lb useful load. Subtract 444 lbs (74 usable gallons of fuel x 6 lbs/gal) and you’re left with 856 lbs for people and stuff.   The airplane has 6 seats but under this  scenario you’ll only be able to fill 4 of the seats with a standard 180 lb person, which leaves 136 lbs for everything else. No, you cannot fill both fuel and seats, but with 4 people you can fly for 3.5 hours with reserves. In the overall scheme of things, not too bad.

The pragmatic question then becomes, when you have a group of 4 people together, how many of them will likely be able to sit for three and a half hours without having to use the restroom? Think about the last road trip you took with 4 people in the car. “Dad, I have to go, NOW!”

For another example, let’s look at a Saratoga II HP – the plane I own – with 1184 lbs of useful load which, incidentally, is the exact useful load of my airplane. This airplane came out of the factory with a whopping 107 gallon fuel capacity (102 usable). That’s over 5 hours aloft, plus reserves, on one tank of gas! With those tanks filled to the brim there will be just 572 lbs for people and bags. Quick math shows that this works out to 3 people with minimal carry-ons or 2 people with a lot of junk in tow.  But, again, if you were able to fill all 6 seats do you think all of those folks will make it for 5+ hours without needing to empty a bladder? The answer is an emphatic “NO!” But, if you have just one or two people who really want to stretch the legs of the airplane — and don’t mind relieving themselves in front of one another — then you can go a long, long way.

Besides, how often are you going to fill every seat? In the 5 years we’ve owned our airplane, we’ve never filled all 6 seats.  5, yes. 6, no. Personally, unless it’s just me and my wife, I plan a stop every 2 ½ to 3 hours, maximum. Even if I wanted to fly longer than that by myself, I rarely do so simply because I’m eager to get out and stretch.

Even the venerable Cessna 210 and Piper Cherokee 6  struggle with this. Yes, they get closer, but at the cost of either speed, or cabin comfort, or maintenance expense. However, throw a few kids into the mix and every one of these planes becomes much more agile.

The clear solution is to buy a plane that will fit 75-80% of your mission. If you need to fly 6 people in a 6-place airplane (or 4 people in a 4-place plane) non-stop halfway across the country, just take the airlines or drive. Trust me, that strategy will not only make you a happier aircraft owner, it will keep your bank account happier too.

In any case, get past the notion that you can buy a single-engine GA airplane and fill the seats and the tanks. Because, unless you have a family of very tiny people, or are only going for the nearby food run, it’s just not going to happen.