Mustang Sally is spot on. If you have been around this business for as long as he, and I, that was pretty normal. Airplanes back then did not have excessive power like they do today. They were first generation jets. The 70 series DC-8 had more extra thrust than the 50's and 60 series. i won't even talk about the -20 and -40's. The -100 series 747's with a 750,000 lb.TO weight would make you pucker up. The -400's, piece of cake at max weight. Now, you throw in backwoods places like Rio Negro, Guatemala City ........et,al; You have mis weighed cargo weights, out and out lying on the weights, kilo's to pound errors, pregnant cows, wet leather, excessively wet produce or flowers coming out of south america. If you don't want to see the red lights at the liftoff end of the runway; don't fly cargo.