The Crash of Flight 592 – Part II

After the crash of Valujet flight 592, several airlines started to implement special requirements regarding the shipment of chemical oxygen generators. Some airlines even directly prohibited their shipment on the aircraft.

These requirements may be found in the “Operator Variations” in IATA's Dangerous Goods Regulations, which are not legally mandatory, but the airline will always have the final call on the acceptance of dangerous goods. Among the companies operating in Argentina, for instance, UPS and LAN regulate the packaging and marking of chemical oxygen generators (Variations 5X-06 and LA-05); British Airways, Lufthansa and Singapore Airlines prohibit the shipment of these devices (BA-05, LH-04, and SQ-06); and Continental Airlines only accepts them as COMAT, or Company Material (CO-05); COPA Airlines and United Airlines do not accept any oxidizing goods (CM-03 and UA-10). Other airlines, such as Iberia, Avianca, TAM, Aerolíneas Argentinas, Varig, Martinair, Air France and Air Europa do not have any special requirement, or Variation, regarding the acceptance of chemical oxygen generators, i.e., they accept them, unless a decision to the contrary is taken which is not stated in IATA's Regulations.

In order to implement the special requirements, it is obviously necessary that the airline staff be able to identify chemical oxygen generators when they are not declared as dangerous goods or if they are declared as such, but under a wrong classification for transport.

A very common mistake while handling chemical oxygen generators in aviation equipment maintenance facilities, is made when classifying the product for transport.

Mistakes in classification may include from declaring that the chemical oxygen generators are non-dangerous goods (or, more accurately, not declaring them as dangerous goods) to assigning the product a wrong risk class, shipping name and UN number.

However, even if a product is classified as a dangerous good, if the shipper is not familiarized with this issue, a wrong UN number and shipping name may be assigned, although the Risk Class may be the right one.

Most shippers usually simplify the issue and give a generic name for transport, without even trying to find a specific designation better describing the product.

If, for instance, we consider the material involved in the crash of flight 592, i.e., chemical oxygen generators which were not spent in the maintenance facilities, and taking into account that they contain a mixture of oxidizing solids (See The Crash of Flight 592, Part I), the material, without analyzing in depth the regulations on transport of dangerous goods, could be labeled as “Oxidizing solid, n.o.s. (sodium chlorate and potassium perchlorate, mixture),” UN 1479. However, packaging conditions would be very different if they are compared to those corresponding to the proper shipping name: “Chemical Oxygen Generators,” UN 3356.

First, it is strictly prohibited to transport products identified under UN 3356 in passenger aircraft. Some airlines even expressly prohibit them in all types of flights (see above). However, if the product has been classified under UN 1479, it may be shipped in passenger aircraft following a certain Packing Instruction which would not be applicable if any other UN Number were used.

This generic category (1) was the one most widely applied at the time of the accident. After the crash, global regulations changes were fostered by the relevant representatives of the United States, in order to include a United Nations number properly describing chemical oxygen generators and including their specific packing instructions. These changes contrast with the current Argentine laws on federal road transport(2), which do not contemplate UN 3356, Chemical Oxygen Generators. Transport by road of such devices should be made under UN 1479, Oxidizing Solid, N.O.S. (sodium chlorate and potassium perchlorate, mixture), i.e., the category used in the world 15 years ago.

Based on the description of the materials of the chemical oxygen generators and of the action mechanism (See The Crash of Flight 592, Part I), we could pose some questions regarding their classification for transport, for instance: If inside the device there is an explosive actuating device, why is a chemical oxygen generator not considered an Explosive?

In fact, this type of risk has priority with respect to the other types of risks, but pursuant to IATA's Regulations, the device must not be considered explosive if it contains explosive substances in an amount or in such a way that their inadvertent or accidental ignition or commencement during transport “does not cause any effect outside of the device or by projection, fire, smoke, heat or high noise.”

Please note that the sole effects external to the device are caused by the heat released by the reaction between the oxidizing materials and the combustible material.

Thus, the possibility of classifying the device as an explosive may be ruled out, given that the actual risk of chemical oxygen generators is that their content itself, and not only the small explosive load, may easily have a reaction. The explosive load is good only to trigger the reaction within the metallic shell, and does not cause any damage or effect on the external shell. Therefore, these chemical oxygen generators must be considered as oxidizing substances, and not as explosive materials.

Even in that case, if a more specific analysis of the classification of chemical oxygen generators is desired, there may be other alternatives which may be considered valid a priori:

• UN 1383, Pyrophoric alloys n.o.s. (iron powder, mixture)
• UN 3363, Dangerous goods in apparatus

The first one is wrong, because it merely describes a reactive component of the device.

The second one does not provide such an accurate description of goods as UN 3356, Chemical oxygen generators, the classification of which has been discussed in international organizations, such as the United Nations or the International Civil Aviation Organization (ICAO).

Even in that case, the acceptance staff at the airlines must be trained to recognize a chemical oxygen generator (or suspect its presence) at the time of accepting the shipment if they are misclassified or poorly packed.

The underlying problem does not lie on the airline cargo control staff, but on the shipper, which in the case of Company's materials is the airline itself or an airline contractor. The cargo control employee may be an individual very well-trained to perform his/her job, who may detect the slightest defect in the documentation or the package and who may even be able to discover dangerous goods not declared in the shipment. However, there is no reason for the cargo control employee to suspect about a wrong category: the cargo control employee will not open the package to check if the substance classified under UN 1383 is actually iron powder mixture. Least of all, there is no reason for the cargo control employee to suspect that a device contains such powder and may generate oxygen if accidentally activated.

When a shipment not declared as dangerous goods is delivered for transport, the airline cargo control employee may have a restrictive criterion and reject such shipment if there is any suspicion that flight safety may be at risk. The cargo control employee may do that. Even in the case of suspicion, the cargo control employee should require from shipper a proper confirmation of the content of the shipment (3).

But the issue is more complex when the load is declared as dangerous by the shipper. Who may tell the shipper that the product classification for transport is wrong and, therefore, that the product may not be transported? The airline cargo control employee? The Enforcement Authority? For most dangerous goods delivered for transport, assigning a risk class, a UN number and an appropriate shipping name entails a minimum chemistry and physics knowledge of which most members of the staff of the Enforcement Authorities and the logistics operators lack. In no means of transport, an airline, road transport company or shipping office is obliged to determine if the classification of a dangerous substance is right and to reject its loading if it is wrong.

As regards the Enforcement Authorities, they intervene in the classification of dangerous goods in specific cases, which are specifically mentioned in transport regulations. No regulation imposes upon an Enforcement Authority the obligation of stopping a shipment if it considers that it has been classified under a wrong category, nor entitles such authority to do that.

All transport regulations state that it is the shipper, i.e., the one delivering the goods for transport, the one who must know how to classify goods for transport. To that end, there is a Dangerous Goods Declaration which must be signed by the shipper, who becomes responsible for the category and the packaging conditions of the dangerous goods. Any intervention by the Enforcement Authority in the classification of products for transport, not expressly stated in the different international regulations, could give rise to abuses by the Authority.

In the case of the chemical oxygen generators involved in the DC9 crash, they were transported as COMAT, or Company Materials. This means that the shipper was Valujet, or someone acting in its name as shipper: Sabre Tech. Both of them were responsible for the tragedy as from the time the generators started to be handled. The problem did not lie on the checking of the cargo when shipping it for the flight, as the cargo control employee reviews the documentation and checks that it is in order and that it is consistent with the information stated in the packaging, without challenging the classification.

The cargo control employee knew that the products were chemical oxygen generators, but as he saw that they were declared only as “empty” (i.e., generators activated in the maintenance facilities by consuming the reaction inside, without any chance of a reactivation), the absence of any risk markings or labels on the packaging was not a surprise for him. They were declared “unloaded” or “empty” and, consequently, classified as non-dangerous goods by the shipper on land. That was indeed the worst classification that could be assigned due to handling mistakes in Sabre Tech's maintenance facilities. They mistook loaded generators with unloaded generators, and they delivered them for transport.

All airlines operating in our countries regularly replace the chemical oxygen generators in their aircraft. All of them may work with their own or third-party facilities, where the final disposal of generators may be handled.

It is often necessary to transport the removed generators by air; this must be done only on cargo flights, as transporting them in passenger flights has been forbidden in order to prevent another Valujet case.

Is it possible that a cargo control employee is very well-trained by the airline to detect undeclared dangerous goods, but that he/she accepts the entry of dangerous goods declared as such even if it is not properly classified?

There is no doubt that that may happen.

However, that classification must be assigned by airline staff, or else by staff of the companies retained for aircraft maintenance, supervised by the airline, as it is COMAT. Then, the question is another: May the airline or the third-party hired for aircraft maintenance make a mistake in the classification of the removed chemical oxygen generators by assigning them a wrong category which allows them to be transported in passenger flights?

If the airline's (or contractor's) staff assigned to aircraft maintenance is not duly trained regarding the risks of chemical oxygen generators and their transport category, then the answer is, once again, yes.

In view of the events, that is too much responsibility for airlines, so they seek to avoid any accident, as one single accident may cause them to disappear as a Company. Furthermore, users trust the airline security thinking more about the aircraft conditions, the pilots' skills or the capacity of cargo control employees to detect undeclared, poorly packaged or wrongly documented dangerous goods. All those factors may be found in the Airport-Air zone. However, what happens on the Land zone and, more specifically, in the aircraft maintenance facilities is essential and is hidden to the users' eyes.

Management of Company Materials, or COMAT, such as chemical oxygen generators admits no errors. Unfortunately, air transport had to learn that after experiencing the crash of flight 592.



(1) UN 1479, Oxidizing Solid, n.o.s. (…), where n.o.s. means Not otherwise specified. The generic designation for transport arises from this category.

(2) In the Argentine Republic, Resolution No. 195/97 of the Secretary of Transport, Technical Standards for Road Transport of Dangerous Goods.

(3) Dangerous Goods Regulations of the International Association of Air Transport (IATA)



Translated by Camila Rufino, Accredited Translator