A basic principal of aviation, which cannot be ignored, even in war: The vacuum created by the camber of an airplane wing is generated by the air rushing across it. This vacuum can be measured in pounds. When the pounds of the airplane and its cargo exceed the pounds of generated vacuum, the airplane will not fly—it crashes.
Fifteen miles east of Kon Tum airfield, a raging battle was in progress with North Vietnamese regulars. It was not going well. We received an emergency call for airlift and headed to the small Kon Tum field to move unspecified fighting equipment to Pleiku.

As I surveyed the situation, an army staff sergeant approached. He looked tired and stressed and gave a half-hearted salute that looked more like a wave. What barely passed as a uniform was dirty and wet with sweat.

I asked if we could be of assistance in moving his equipment. He pointed to a three-axle truck, the kind with the high chuck wagon canvas top. Fastened to the hitch on the truck was a 105-mm Howitzer cannon on wheels. He had been ordered to get it all to Pleiku as soon as possible.

When I inquired about the weight, the sergeant said the truck was 20,000 pounds and the gun another 15,000 pounds. Taking into account runway length, elevation and temperature, I made some calculations and told him we could take the Howitzer or the truck but not both. With a look more of desperation than disappointment, he insisted both had to go, the battle depended on it. I recalculated, using all the fudge factor that I dared. There was no way—I could only take off with a maximum cargo of 25,000 lbs. I told him again, either the truck or the gun but not both. As he turned to discuss the problem with another sergeant, I got the impression he didn’t believe me. I guess he thought, hey man, they don’t call this airplane the C-130 Hercules for nothing. But he didn’t comment.

With obvious reluctance, they decided to take the truck without the gun.

As the truck drove up our back ramp, I became uneasy. The truck seemed to require high power settings, even in the lowest gear, and as it proceeded into the cargo hold, the airplane settled ominously lower. I got a sick feeling: something was wrong.

I walked up the ramp to the truck and moved the canvas. Stacked five feet high were wooden boxes. “Sergeant, what is this?”
Sheepishly, “That’s the gun ammunition, sir.”
“How much does it weigh?”
“Sir, I don’t know exactly but about 20,000 pounds. When you said you could take the truck, I figured you could take what was in it.”
“Were you going to accompany your truck to Pleiku?”
“Yes, sir.”
“Sergeant, nobody would have made it to Pleiku. You, along with the rest of us, would have died in flames at the end of the Kom Tum runway. It would have been a spectacular ball of fire fed by JP-4 fuel and 20,000 pounds of 105-mm Howitzer ammunition.”