THE ART OF TIE-DOWN

The art of Tie-Down Flying a commercial cargo airplane has always required at least five basic elements: A competent crew An airworthy airplane Airworthy ULD (Unit Load Devices) A faultless tie-down when needed

A correct complement of aviation fuel

(Lock assy on a modern plane. Locks provide up and side restraint)

All of our readers will know what tie-down is and will certainly not need a definition, however when looking at a definition in my memory and not able to recall one that would have been given in my early airline days ( it was long long time ago) I would propose the following :

Tie-Down is the fastening or securing of a load to its carrier by use of ropes, cables and other means to prevent shifting during transport. (It is also used as a noun to describe the material employed to secure a load. (Dictionary of Military and Associated Terms . US D.O.D 2005)

(Fwd/Aft lock restraint system)

Obviously, the various settings of the airplane controls during the take off and flight phases is associated with the CG of an airplane once loaded with its cargo (The CG or Center of Gravity of an aircraft is the point over which the aircraft would balance).

It is therefore vital that cargo, regardless if contained in ULD or simply in some cases (special loads for instance) tied to the aircraft floor itself, does not move during take-off or any of the flight phases from the time the airplane lines up on the runway to the time the wheels touch down and braking action is used to slow down the airplane. Should the cargo not being properly secured, life of the crew and integrity of the airplane would be definitely at risk.

During the take-off phase, aircraft controls are set in such a fashion that , at a given speed called Vr the aircraft should rotate and lift off the ground without undue efforts by the flight crew.

(Special loads will require special tie-down : a SWA B747-200 being loaded with pieces of oil equipment on a charter flight)

When loaded in ULD like "igloos or containers of various types and size", the cargo is restrained by the “walls” of the “containers”. ULD , regardless if container type or cargo pallets (netted) are immobilized on the airplane floor by use of various pallets or container locking devices providing sidewards, front, aft, and vertical restraint depriving said ULD of any possibility to move in any direction and endanger both the crew and the airplane itself.

Life would be easy if cargo was ALWAYS carried in containers .

Locking the ULD in their correct position, checking that locks, brakes, side-rails are engaged would be a routine operation. But often in the cargo business, non-standard kind of load (ranging from cars to oil-platform equipment, or a full load of live chicken to anti-aircraft guns or micro-wave telephone equipment) requires to be specifically tied down to the airplane floors using a vast array of specific tie-down equipment such as straps, steel cable, chains, turnbuckles, hooks, tie-down sockets of all kinds.

(A cargo "ring" to be positionned in the "seat track")

(Seat track)

Because of the airplane structural limitations, certain positions in the aircraft will be limited on both weight and tie-down capacity. Complicated calculation regarding the type of tie-down to be used and the position of tie-down points to be selected have to be conducted either by the “operation” people or by the loadmaster himself if it is the case.

(Special loads, special tie-down, here with chains and hooks in a military airplane)

In most of the cargo airplane, “seat tracks” embedded in the floor can be used as “tie-down” points but have also their own limitation.

Military airplane, sometimes being developed with their own “ military type” tie-down points, and geared to carry routinely heavy military equipment are equipped with military specific tie down equipment, quite often with heavy chains which would not be used on a civilian commercial carrier.

Of course, all of the tie down equipment should have passed FAA (Federal Aviation Administration) lab tests.

Forget the old rope used out of India to secure a returning-to-repair military helicopter, or the Russian origin straps “borrowed” from “Аэрофло́т following the pick-up of Russian trucks on their way from Kiev to a “ friendly country”.

(108 '' MAC ( Military Airlift Command) pallets used is military airplane. Can be accomodated also on civilian cargo aircraft provided the Locking system is adapted )

Aviation trade is very demanding ! Working on a cargo plane often reminded me of what firemen are trained for : being able to do the right thing at the right time with the right type of equipment.

Straps will be rolled-up and ready for use, and one will know by heart all of the various airplane floor limitation. One will not put one’s finger to close to a “ turnbuckle” when opening it by fear of being mutilated, one will not attach 10 cargo straps to the same tie-down lock by fear of tearing off the airplane floor, thus grounding the airplane and being assassinated by one’s hierarchy…Although airplane tie-down equipment may be sophisticated, nothing remains as sophisticated as human intelligence and analysis.

Checking, verification, re-checking are tantamount to a longer life in the air cargo industry, especially if one is flying with the load and responsible for its safe guarding. Flying around the world, one will need a Maglite®and a stock of batteries to be able to check after each airplane loading, that locking devices are correctly engaged and that restrains of all kind will provide the ad-hoc immobilization of the cargo.

(Better understand this before you start a career...it can save your ass when in operation)

(Costly mistakes....we know what happened, don't we?)

(10 ft containers and a 20ft container seen in a SWA B747-200 in Le Bourget Airshow long ago)

Heavy duty gloves will also be required to make sure that one avoid the terrible wounds by cutting edges on some of the cargo carried on board ! You do not have enough straps on board ? Go and look for another US carrier to “ lend “you some, even if it is known that you will never give them back !

In my active days, It was called airline solidarity! There are no US carrier around ? What the F…..go and snatch whatever you can from whatever airline is operating in the area…Even if not allowed, it is better to fly using someone else tie-down equipment, that without, or with a “ minimal” equipment. You are lost with the calculation of how many straps should be used ? an an additional 15% to the number you believe is right …!

Incorrect, improper or missing tie-down can lead to catastrophies. In aviation , there is not always one single cause for an accident. Verifications and checks should always be conducted before take off….conducting these after take-off, and correcting mistakes is a taxing activity !

Loading up a full main deck of live chicken in Masstricht and being short of straps (but not wanting to delay the airplane) we took off one day and when reaching Vr, the entire load moved backwards by 30%, thus liberating a large part of our live and stupid cargo. Flying with a B 747 on that day, a fairly large part of that population found legitimate to go and perch on the various cables lining up the ceiling over position 29 !

We had to dislodge them with the fire extinguisher extension canes as we could not reach the ceiling . I Know of at least two accidents originating in improperly checking the tie down after landing or before take off. One of them in 1979 (http://aviation-safety.net/database/record.php?id=19831011-0), no I Was not a part of it (or at least I do not recall).

Other incidents took also place, along my career, most of them could have been avoided with a bit more brain and less “ combat fatigue”…Re-tiying down cattle stalls on DC8 loaded with corrida bulls on their way from Seville (Spain) to Bogota ( Colombia) was an unforgettable experience. Incorrect tie down can have dreadful consequences..

On April 29, 2013, at approximately 3:30 p.m Afghanistan time (11:00 UTC), National Airlines Flight 102, a Boeing 747-400, registration N949CA, operating a charter cargo flight for Coalition forces, crashed soon after takeoff from Bagram Airfield in Afghanistan.

All seven crew members on board died in the crash. Although Taliban spokesmen claimed responsibility for the destruction of the aircraft, initial reports based on communications from the crew after takeoff indicated that the crash probably resulted from a load shift, causing the aircraft to experience a high-aft center of gravity, becoming unstable and eventually leading to the loss of control by the pilots.

One more reason to remember that the art of tie-down is difficult and cannot suffer mediocrity or mistakes.

(Fatal mistake)

(Seaboard World Airlines pictures are courtesy of Michael Bradish, then operating supervisor in SWA Detroit operation, and Capt Ken KAHN, one of SWA B747 Pilots, who maintains the Seaboard and Western website (http://www.seaboardairlines.org/seabhist.htm)