Why Your Pilots Are so Fussy About Weight

On Feb. 2, 2005, in a high-profile accident, a business jet ran off the runway, went through an airport perimeter fence; across a six-lane highway (where it struck a vehicle); and onto a parking lot before crashing into a building. The 11 occupants of the aircraft and the two people in the vehicle were injured. The airplane was destroyed by post-impact fire.  

Investigation authorities determined that the probable cause of the accident “was the pilots’ failure to ensure the airplane was loaded within weight-and-balance limits and their attempt to take off with the center of gravity well forward of the forward takeoff limit, which prevented the airplane from rotating at the intended rotation speed."  

Serious accidents from improper weight and balance are not rare. Of the last 46 accidents involving private and air taxi turbine business airplanes caused by incorrect weight and/or balance, more than 40 percent resulted in fatalities.  

All aircraft have a maximum takeoff weight and a center of gravity  (CG) range that must be adhered to for correct aircraft balance. In flight, weight drops and the CG shifts as fuel is burned off. Before flight, the CG position is determined by how much weight is loaded aboard and how that weight is distributed. Exceeding weight and CG limitations changes the flying characteristics of the aircraft, especially crucial on takeoff, and can result in the aircraft becoming dangerously unstabilized. 

Every aircraft has a designed maximum weight and comes off the production line with an empty weight. After adding cabin outfitting and the weight of the minimum number of pilots, the aircraft is heavier at its now “operating” empty weight (OEW). The weight left between OEW and maximum weight is called useful load: what’s available for fuel, passengers, baggage and cargo. Take away the fuel, and what remains is the payload.

While adhering to proper weight distribution and CG limits, available payload is basically dependent on the non-stop distance the mission requires. Some airplane models can top off fuel, baggage and fill all the passenger seats, and still have decent non-stop capability. On most airplanes, however, the pilots must trade off between the number of passengers and the amount of fuel. The math is simple: more passengers means less fuel can be loaded, resulting in shorter non-stop flights and vice versa. In some cases, carrying the desired number of passengers means there is no weight left to add a useful load of fuel at all. 

Taking off over maximum weight is inherently dangerous. Attempting to takeoff over weight and out of correct CG range is usually calamitous. This scenario can be even more disastrous if an engine or other essential aircraft system suddenly stops working at this critical phase of flight. Depending upon their extent, a faulty weight and/or CG range can make the difference between being able to handle the aircraft or losing control. 

So if your pilots turn down a request to offer an otherwise empty seat to a guest, or balk when you show up with a passenger who isn’t on the manifest, don’t take it personally. They aren’t being rude. They’re doing exactly what you pay them to do: keeping everyone on board safe.