October 2021 saw a Cert Alert issued by the US Federal Aviation Administration (FAA)1, regarding inferior fire performance with Fluorine Free Foam’s (F3s), when compared to C6 US Mil Spec QPL AFFFs.

This document confirms FAA’s priority in preventing public safety from being potentially compromised: “While FAA and DoD testing continues, interim research has already identified safety concerns with candidate fluorine-free products that must be fully evaluated, mitigated, and/or improved before FAA can adopt an alternative foam that adequately protects the flying public.

The safety concerns FAA has documented include:

  • Notable increase in extinguishment time;
  • Issues with fire reigniting (failure to maintain fire suppression); and
  • Possible incompatibility with other firefighting agents [eg. dry chemical, other foams], existing firefighting equipment, and aircraft rescue training and firefighting strategy that exists today at Part 139 air carrier airports.

While FAA and DoD continue the national testing effort, the FAA reminds all Part 139 airport operators that while fluorinated foams are no longer required, the existing performance standard for firefighting foam remains unchanged (whether that foam is fluorinated or not). Airports that are currently certificated under Part 139 will remain in compliance through use of an approved firefighting foam that satisfies the performance requirements of MIL-PRF-24385F(SH). If a certificate holder identifies an alternative foam, not currently approved, that it believes satisfies the performance requirements, it may propose that agent to FAA for approval.”

Few others seem to be so serious when considering the potential consequences and liabilities for travellers, processing and facility employees, firefighters, emergency responders, when leading Fluorine Free Foams (F3s) and developmental prototypes cannot meet mandated performance requirements. US Military Specification PRF 24385F (SH) Amendment 4, April 2020 (Mil-Spec)2 is arguably the toughest fire test Standard that firefighting foams have to face. It now accepts F3s for use if they can pass, as set out in the 2018 FAA Reauthorization Act, but none can meet this challenge. Shouldn’t this also be a warning for industrial application users, like you.

The International Civil Aviation Organisation (ICAO) omits necessary studies on important secondary properties like dry chemical compatibility, corrosion of aircraft and fire truck foam tanks, accurate proportioning, storage stability, mutual aid etc, as spelled out in the US Mil standard, which need to be met for most applications. These are not included in ICAO’s claimed ‘equivalent’ Level C fire test using a single freshwater fire test to pass, not the 7 separate fire test passes required by MilSpec. These important additional fire protection properties were waiting for a promised F3 performance equal - that never came.


ICAO Level B & C fire test specifications weakened

Previously unacceptable AFFFs and F3s now pass what was a more difficult ICAO standard3 which excluded them before 2014. ICAO provided no notice to the traveling public that their safety had potentially been compromised by these changes.

These revised International Civil Aviation Organisation (ICAO) Level B and C fire tests3, under which most Non-US and European airports are mandated, do not seem to have improved Safety Standards, and may have compromised our public safety. Surely an unacceptable position for Aviation, but there are also ‘lessons to be learned’ for industrial applications.


ICAO Level C approved F3s FAIL Level C fire test at FAA’s new “state of the art” facility

Recent FAA test reports4 showed 90secs Jet A1 preburn created similar results to gasoline (not the 60secs preburn currently required by ICAO). NONE of 19 F3s tested on Mil-Spec and ICAO Level C by FAA was able to pass either test (9 were commercially available, the rest were developmental). Several failed to extinguish the fire, some exceeded 2mins extinguishment on Mil-Spec (30secs requirement). Others took over 3mins against ICAO Level C’s 2mins requirement. Only the best achieved 38secs on MilSpec; 2mins 12secs on ICAO Level C. 6 of 9 better performing F3s failed burnback testing (66%). 

ALL Fluorine Free Foams (F3s) tested that claimed ICAO Level C approval ratings, failed to pass that test when run in FAA’s new indoor, state of the art fire test facility. Why? …Are such products ‘borderline’ so sometimes they pass, sometimes they don’t. Certainly it seems to be increasing (not reducing) dangers to firefighters and public safety by these changes, when most expect the duty of fire protection is to increase - not decrease- fire safety. Presumably such demonstrated F3 performance limitations would similarly impact major Industrial fire scenarios.


Safety Concerns Underlined by More Comparative Testing

Comparative NFPA-RF 2020 fire testing5 results with 5 leading F3s support FAA’s concerns, when widely used, stored and processed commercial fuels like gasoline were used (not just convenient test fuels like heptane). F3 testing required 3-4 times extinguishment densities of the C6 AR-AFFF control on Mil-Spec gasoline, and 6-7 times C6 AR-AFFF density on E10 (gasoline with 10% Ethanol added), while F3s also exhibited inferior burnback capabilities on these common fuels, which should also be expected in industrial settings. It is important to seek approval confirmation on these tougher fuels likely to be stored/used in your facilities, before accepting any changes in foam concentrate.

 Major potentially catastrophic fires demand swift action with reliable effective C6 AFFF agents to protect lives (including firefighters), while minimising resulting environmental harm and infrastructure damage. -

 Major potentially catastrophic fires demand swift action with reliable effective C6 AFFF agents to protect lives (including firefighters), while minimising resulting environmental harm and infrastructure damage.

2019 US Naval Research Laboratory’s (NRL)6 comparative fire testing also independently found similar outcomes.  The best Fluorine Free Foam (F3) tested required 2.5 times more than the benchmark C6 AFFF, to extinguish MilSpec gasoline pool fires in 60 secs. Second best F3 required 3.75 times more, third F3 required 5 times more and the least effective F3 required 6.25 times more foam agent than C6 AFFF to extinguish the same gasoline pool fire in 60 seconds. These differences increased further with faster extinguishment requirements. Considering such disturbing potential impacts, is also important during future industrial emergencies.


Lower Health and Environmental concerns confirmed for C6 AFFFs

Increasing acceptance of restricting legacy C8 foams by legislators has been necessary to protect human health and environmental impacts from a small percentage of ‘bad actor’ legacy PFAS (notably PFOS, PFOA and PFHxS), each with long human half-lives of 3.8 to 8.5 years and undesirable bioaccumulation and toxicity characteristics harmful to the environment7. Widespread restrictions from training and testing with preferences for F3s, have also reduced risk of C8 environmental escapes by around 90%, with use commonly restricted to life saving emergencies only.

Sadly, the very different more benign characteristics of high purity C6 AFFFs have become misleadingly ‘stereotyped’ as ‘similarly undesirable’, despite the facts confirming C6s have very different behavior giving significantly lower health and environmental concerns.

C6 PFAS are categorised as not Bioaacumulative (B) and not Toxic (T)8,9. Despite still being Persistent (P), without ‘B and T’ potential for harm to human health and our environment from C6 AFFFs is substantially reduced. C6 (PFHxA) human half-life averages just 32 days, quickly excreted in urine10, preventing concerns of bodily build-up over time. This was confirmed by the latest Centre for Disease Control National Health and Nutrition Examination Survey (NHANES) 2017-18 blood serum data set. This confirmed C6 fluorotelomer breakdown product (PFHxA) was not detected in any blood sampled, from all age groups and demographic groups of the general US population, despite inevitable exposures11. This study also confirmed historic population blood levels of PFOA, PFOS and PFHxS are all dropping significantly due to legislated restrictions, as their data since 201111confirms. So restrictions have worked, suggesting continued use of C6 AFFFs just for emergency fires where lives can be saved (including firefighters), is justified.



Three sets of testing identified requirements for using F3s higher application rate, gentler delivery, and higher expansion ratios, compared to C6AFFFs. It caused reduced throw and greater wind effects from F3s, forcing firefighters closer to flames and increased risk, with slower fire control and extinguishments also likely outcomes; also relevant to industrial applications. Such reduced F3 performance could severely impact industrial firefighting capabilities.

The evidence suggests FAA’s public safety concerns seem fully justified. Especially when C6 AFFFs do not suffer significant health and environmental concerns like restricted legacy C8 PFAS foams. The use of C6 AFFFs in training and testing has also been virtually eliminated, further reducing the exposure potential to just real emergencies - where it is critically needed to save lives.

Otherwise, people’s lives could be exposed to increased danger in your industrial facilities - from unacceptable hazards and increased safety risks, IF F3s were used, instead of C6 AFFFs.

You have a duty of care to staff, emergency responders, nearby communities and Society at large, which it seems cannot be met by such demonstrated inferior F3 fire performance. When proper evaluations are fully considered, we should be accepting that ongoing C6 AFFF usage is essential to provide that fast, reliable, effective fire performance during potentially catastrophic flammable liquid fires, so critical when saving lives.