Flying your aircraft above its maximum gross weight can be done, but not in all circumstances.

By Joseph E. (Jeb) Burnside

I regularly fly my airplane some 250 pounds overgross. But, I do it legally, since it’s equipped with an STC’d tip tank installation. The STC (supplemental type certificate) allows operation at a maximum gross takeoff weight of 3550 pounds, an increase of around 7.5 percent from the airplane’s original 3300-pound gross weight when it left the factory.

But there’s no paperwork accompanying the admittedly older STC providing performance charts at the higher gross weight. There’s no question performance suffers at the higher weight, but I’m legally allowed to use the older, lighter weight in computing performance. To compensate, I make sure I use runways of adequate length when operating at the…