Pierced steel planking is locked together with steel clips to form a makeshift runway.
Caribou operations in Viet Nam were restricted to runways at least a thousand feet long, and many of the fields were euphemistically called “unprepared runways.” That means they were dirt runways, often muddy and sometimes dry, but always with deep ruts from previous landings in the muck. Sometimes the runways were covered with pierced steel planking (PSP), flat steel planks with 3” holes through them to reduce weight, locked together to form a runway (see photo at left). They were very slick when wet and even slicker with a thin coat of wet mud. A thousand feet may sound like a lot, but approaching a 1,000-foot runway at higher weights, sometimes near the Bou’s 28,500 pound maximum, was pucker time.
For training in Sewart AFB, Tennessee, we had a 1,000-foot dirt runway marked off with chalk lines. Wire-framed 18” x 24” fabric markers (see photo below) were placed every 100 feet to show the distance remaining to the end of the runway. There was lots of flat space surrounding the runway, so a landing that ran off the runway, whether long, short, or off to the sides, didn’t hurt anything except the pilot’s pride. While all of the students were fully qualified Air Force pilots, they were now learning a totally unfamiliar airplane, and most had never landed on a runway less than 6,000 feet long.
On one occasion, an aircraft went off the side of the runway and ran over a runway marker, which bounced up and put a large gash in the belly of the aircraft. How could a fabric marker open up a hole in an aircraft fuselage? Well, it couldn’t. Turns out that the fabric markers had been replaced with steel signs, which airfield administrators had requisitioned because, as they later explained, “The pilots were always running over the markers and tearing them up!” Practice landings were halted briefly and the steel markers hastily removed.
Wire-framed fabric runway markers placed every 100 feet along grass or dirt airstrips help the pilot judge how close he is to the end of the landing strip.
