Magnesium chloride is known to be an exceptionally corrosive material, particularly in its use as a deicer by transportation agencies and airports around the world.

The US Environmental Protection Agency has banned the use of magnesium chloride as a deicing agent in and around aircraft. In its report on deicing operations, the EPA stated, “Salts, including magnesium chloride … are not approved for use in aircraft operational areas because they are corrosive to aircraft.” The Federal Aviation Administration has similarly warned against the use of the material.

Corrosion and the reduced structural integrity of aircraft is an economic burden and affects operational capacity, but more importantly it is a safety issue. The presence of corrosion can lead to loss of structural integrity and potentially catastrophic failure. Fire retardant that is loaded on an airplane will, at some point, come into contact with almost every part of that plane, especially those metal surfaces – like aluminum alloys –  that are most susceptible to corrosion. With an exceptionally corrosive material, the potential for aircraft failure – particularly under the aggressive operational environment experienced during wildfire fighting – is an issue that should be well understood.

Is It Worth the Risk?

Phosphate-based fire retardants have a record of safe, effective use stretching back nearly 60 years. The infrastructure is in place to effectively deploy them and has kept pace with increasingly difficult fire seasons over the past decade. Today, there is consideration of incorporating a new chemical technology into the firefighting arsenal. Questions arise about the ability to use multiple products on a single aircraft. Are they compatible? Will they introduce additional cleaning and maintenance requirements? Is there a chance that two separate aircraft forces will be required to manage both technologies? What would be the cost and limits on operational capability this might introduce?

There is no testing currently in place to adequately understand these issues. Before magnesium chloride technology is broadly deployed, it makes sense that these questions be investigated, and rigorous testing be done.