UPS Flight 6 emergency landed last week near Dubai. About 20 minutes after taking off from Dubai, the crew sought to return, reporting smoke in the cockpit and trouble maintaining altitude. The plane was unable to make an emergency landing in Dubai on its first pass, then began losing altitude and crashed inside a UAE military camp. The Captain and First Officer were killed in this accident.

This may have been preventable if cargo planes are required to carry automatic fire extinguisher system. For some time now the NTSB (National Transportation Safety Board) has been arguing with the federal regulators for use of such devices in the main cargo hold, where most of the cargo on a freighter is ferried (The FAA requires fire suppression systems in all passenger aircrafts and in the lower holds of cargo aircrafts).

These fire extinguishing systems are usually activated by the flight crew in a response to abnormal heat detection in an aircraft hold. The systems operate in a dual function: (1) Part of the available fire suppression capability is deployed in an ‘instant’, or ‘knock-down’, discharge of extinguishing agent and (2) the remainder is deployed more gradually over a longer period of up to an hour, to assist in preventing re-ignition.

The Federal Aviation Administration reiterated that such fire control systems are too expensive. For large cargo planes, a 2009 study conducted for the FAA estimated the total cost of installing a fire suppression system at $7 million per aircraft. Operating costs would be another $140,000 per aircraft per year.

For years, the airline industry has been searching for an alternative to Halon 1301, the most common fire extinguishing foam used in fire suppression systems on the smaller, lower decks of cargo planes. To date, those efforts have been largely unsuccessful. Various alternatives to Halon have been examined including water misting, inert gas and dry powder, either alone or in combination and the FAA has developed Minimum Performance Standards for these systems. To further complicate this issue no new Halon is being manufactured since 1994, because it has been identified as an ozone destroyer and Halon systems still in use depend on aviation suppliers to recycle the gas.

Then FedEx last year unveiled the industry’s first onboard automatic fire-suppression system for main cargo holds.  

“… It features a network of infrared thermal sensors, (Argon) foaming-agent generators and an overhead cargo-container injector. If heat is detected by the sensors, the fire suppression technology located above each cargo container is activated, simultaneously alerting crew members. The metal container is pierced by an injector apparatus and filled with an argon-based biodegradable and non-corrosive fire-suppression foam that controls and extinguishes the fire in minutes. Cargo in other containers is unaffected by the system’s activation, and the foam has only minimal impact on packages housed within the container.

For palletized freight, a special fire-retardant blanket is used to cover the cargo; it restricts the level of oxygen around freight, effectively serving as a fire suppression tool…”

FedEx reported that their new fire suppression system is quick and effective on classes of fires started by:

• Ordinary materials such as paper or lumber (Class A)
• Flammable or combustible liquids such as gasoline or kerosene (Class B)
• Combustible metals such as lithium, magnesium titanium, potassium and sodium, which burn at extremely high temperatures (Class D)

Shipments that are subject to what would be considered Class C fires (electrical equipment) is carried separately in the lower compartments of the aircraft and are protected by standard halon systems.

UPS Airlines is taking a different approach: should a fire be detected, cargo pilots will follow FAA guidelines to depressurize the main cabin and climb to at least 20,000 feet of altitude to starve flames of oxygen. However, some argue that a maneuver like this and diverting to an airport can take up to 30 min.

The cause of the crash and whether fire played a role has not been determined.