Refer to figure.
Basic Empty Mass (BEM) is the mass of the aircraft with the basic equipment, unusable fuel and other fluids, fire extinguishers, pyrotechincs, emergency oxygen equipment and supplementary electronic equipment. Basic empty mass is determined by the manufacturer, recorded in the weighing schedule and is amended to take account of changes due to modification of the aeroplane.

• Basic Empty Mass = nose wheel mass + left main wheel mass + right main wheel mass.

Since this aircraft is placed and weighed on jacks,

• Basic Empty Mass = tail jack point mass + left main wheel mass + right main wheel mass = 3345.34 + 19 720.14 + 19 730.37 = 42 795.85 kg