Towing the Line
Tony Vasko ruminates on the evolution of towing equipment
By Tony Vasko
Moving aircraft is one of those routine airport jobs that seems simple but requires care and some planning to safely accomplish. Looking from the terminal, you can see the pilots steering their aircraft in and out of the gates with only one person on the ground to wave wands at them. Easily overlooked are the wing and tail walkers where the ramp is tight. Aircraft are awkward on the ground, at least most jets are, and their wings and tails reach out — eager to make contact with other aircraft or light poles or solid terminal buildings. These lead to some very expensive and time consuming out-of-service events.
ALL MAKES AND MODELS
Taxiing under engine power would seem to be the easiest way to move an aircraft, but it's not. You burn a lot of fuel, eat up some precious engine life and blow a lot of equipment about in the jet or prop blast. So towing is the preferred method. Here you ran into the problem of non-standardization. Each aircraft manufacturer had its own ideas on how to couple a tractor to its aircraft - although there has been some improvement in this and some standardization of head design has taken place.
For airlines, this non-standardization is a pain. They have to buy tow bars specific to the aircraft type(s) they are operating. For FBOs and ground handlers servicing many airlines, it can be a dreadful problem.
HOOKS, CLAWS, PINS, AND GRABBERS
In the 1950s, Lockheed Air Service in New York was the FBO of sorts for Idlewild Airport. It had originally been Willis Rose Aviation out on Long Island. The move to Idlewild came with an inherited horde of ironmongery comprised of a selection of aircraft towbars embracing both past and present types that filled a small storage yard. Some were long steel trusses while others were steel pipe. Some were very short, others very long. All had an eye on one end but the other ends were a bewildering array of hooks, claws, pins, and grabbers of every description. Some had hydraulic pumps and pistons to raise or lower the wheels; others had lever-type mechanisms, while still others had worm gears and wheels.
I had rapidly become familiar with the common variety of towbars that we used every day. The DC-4, DC-6, and DC-7 all used the same "through the nose wheel axle" attachment type of bar. It was fairly stubby and light and didn't need any fancy hydraulic or screw-jack systems to raise and lower it. The Constellations used attachment lugs on the nose gear itself. These required more precise aligning and the towbar was much more complicated. Most modern jets use the same type.
There were some very impressive models that looked like, and were the same size as, the boom from a crane. These were for tail dragger types like the C-46, the DC-3, and the Lockheed Lodestars. They had to be very long to go under the fuselage and hook on the tailwheel, yet still provide clearance for the tug to work around the elevators. Being of steel truss construction, they were also quite heavy. Humping them into place could be a job, particularly with snow and ice on the ground. There was one very rusty, but still impressive, towbar in that yard that I was assured was for the B-17. I never got to try it on one.
Truly the most impressive towbar I have ever seen belongs to the Russian AN-125. With two nose gears to contend with, it has two long girder sections vee-ing out behind the tug. These "tramp steamers of the sky" go anywhere, anytime, but they have to carry their bar with them, as AN-125 towbars are not common stock at most airports. It would take up a good part of the freight hold except they cleverly designed it to fold. Even so, it makes a unique package but is a very competent piece of engineering. I saw it in use in Tijuana, Mexico where two AN-125s were hauling out 100-ton loads of grapes destined for European tables.