Public safety concerns: Question Fluorine Free Foams (F3s) suitability


21 December 2021



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Mike Willson, firefighting foam, and foam systems specialist, talks to International Airport Review about the questions over the suitability of PFAS-Free Foam alternatives.

The quest and challenge to replace Per- and PolyFluorinated Alkyl Substances (PFAS) in AFFFs (Aqueous Film Forming Foams) for firefighting, by using PFAS-Free Foam alternatives, better known as Fluorine Free Foams (F3s), seems to be reaching fever pitch, as timelines for anticipated replacements draw closer. Yet, necessary F3s fire performance still seems increasingly elusive, without clear evidence of adequate, reliable, effective capability under realistically tough conditions. Manufacturers have made huge F3s efforts delivering incremental improvements over 20 plus years, but without the safety equivalency necessary to justify the major transition many are seeking. It’s frustrating of course, but increasing evidence confirms this gulf between requirement and what is possible, and remains stubbornly significant, potentially jeopardising lives.

FAA voices concerns over public safety

The U.S. Federal Aviation Administration (FAA) has recently issued Cert Alert 21-05, (Oct. 2021)1 confirming their priority concerns for public safety: ‘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)
  • Possible incompatibility with other firefighting agents, existing firefighting equipment, and aircraft rescue training and firefighting strategy that exists today at Part 139 air carrier airports.

While the 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)2. 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 seriously considering the potential consequences and liabilities for our travelling public, flight crews, and emergency responders, when leading F3s and developmental prototypes do not meet the performance mandate of U.S. Military Specification PRF 24385F (SH) Amendment 4, April 2020 (Mil-Spec), now accepting F3s that pass, as set out in the 2018 FAA Reauthorization Act. Forcing F3 adoption prematurely could reduce public safety, something most would agree neither legislators nor operators should be compromising. Everyone’s duty of care should be protecting lives and public safety. Still some prematurely declare ‘AFFF is defunct’3, based on easier approvals, but without ‘realistic worst case’ major F3 fire incident verification. Are we jumping the gun? Confusing legacy issues with safety? Drastic reductions in AFFF use (typically 95 per cent) have already been achieved by substituting F3s for training and testing, reserving AFFF ‘life savers’ for emergency use. All foams have impacts on the environment if discharged directly. All foams become inextricably mixed with fire’s noxious breakdown products, including PFAS from other sources (notably seats, carpets, computer screens, mobile phones, other electronic equipment, Li-ion batteries, cabling etc.) abundant in virtually all modern aircraft. Should we risk disregarding the primary purpose of firefighting foams: fast, reliable, effective, and efficient preventatives of wide ranging, potentially ‘disaster making’ scenarios? Undue haste might be ‘courting disaster’?

Claimed ‘F3 successes’ at London Heathrow: incorrect

Some major airports have already transitioned to Fluorine Free Foams (F3s), fully accepting small scale International Civil Aviation Organisation’s (ICAO) Level B, rarely the tougher Level C approval4 and local testing as adequate indicators of likely F3 ‘success’, should the worst happen. Seemingly without direct proof in major incidents, as none (except Dubai) seem to have suffered major aircraft fires. Perhaps many were encouraged by two 2013 claimed F3 ‘successes’ at London’s Heathrow airport (LHR)? Official UK Air Accidents Investigation Branch Reports confirm they were not factually correct. An Airbus A319 engine fire at LHR (May 2013)5 was controlled, almost extinguished by on-board fire suppression systems before landing. Calculated fuel leakage rates reportedly emptied the wing tank before landing. A further Boeing 787 fire at LHR (July 2013)6 occurred when unpowered, unoccupied, and parked. Firefighters extinguished a small slow-burning composite material cabin roof fire (likely from Li-ion battery fault), using a water hose-reel internally. Have we, should we, be adequately considering potential F3 liabilities and consequences during major aircraft fires – before disaster strikes? The FAA seems to have done. How would your airport perform, using only F3s?

Major accident comparison tells a disturbing story

A Boeing 777 engine detachment fire in Dubai (August 2016)7, during a landing ‘go-around’ manoeuvre in 48oC (118oF) heat with wind shear conditions. Despite repeated F3 attacks, full extinguishment took 16 hours after impact and the plane was destroyed. A brave firefighter died when a fuel tank exploded, nine minutes into the fire. All 300 passengers were evacuated three minutes earlier: critically before that explosion. Imagine the carnage, had evacuation been delayed. Seconds count saving lives. Investigation reports did not explain why this fire continued to burn, nor whether the firefighter’s life may have been saved, had the foam been effective. Foam samples were re-tested and passed ICAO Level B4 certification in northern Europe, but why were they not tested under Dubai’s summer heat; better representing accident conditions? Society’s expectations were not met; perhaps a future warning; perhaps endorsing the FAA’s decision.

Everyone’s duty of care should be protecting lives and public safety”

Contrast this with Singapore’s Boeing 777 engine fire (June 2016)8, loaded with several thousand gallons of jet fuel. A problem two hours out forced a return landing with fully involved engine and wing fire at Singapore Changi Airport (SIN), in tropical 32oC (90oF) heat. The investigation report confirmed thrust reversers spread fire into the core of the engine. All fire was extinguished in five minutes using fluorinated AFFF and FFFP agents. 241 passengers and crew remained on-board, safely disembarking 15 minutes after the fire’s extinguishment and there were no resultant injuries; minimal disruption and the plane was repairable. Suppose extinguishment was delayed; unexpected flashbacks, failed fire control, might it have ended differently?

The FAA considered safety concerns… have others?

Imagine your loved ones paddling through exposed pools of fuel, mostly covered with a foam blanket, but vulnerable to flashbacks, churning the foam while rushing to escape. Flames still evident in places, but without fuel shedding and vapour sealing additives, intentionally missing to avoid potential persistence issues in our environment (which may not cause harm when also not bio accumulative, nor toxic). Is that ‘priority choice’ protecting people’s safety? Plane crashes likely harm, even kill, many people quickly without reliable fast, effective, fire extinguishing action. Innocent, untrained passengers, many infants, disabled, and elderly are usually involved. Incident patterns mostly involve some panic, grabbing personal effects, carry-on luggage, causing delays, obstructions to most evacuations. Time is critical when maximising lives saved. Are we prepared to compromise existing safety protections, without clear evidence of F3’s effectiveness? Modelling suggests a three minute survivable cabin atmosphere, before being overcome by smoke9. It also recognises that ‘…for the case of aircraft, as in buildings, small-scale laboratory tests do not necessarily reflect behaviour of material in real life situations’, making large-scale fire testing probably essential. It’s been done effectively at 16,000ft2 (1,486m2) with AFFFs at Mil-Spec application rates10; but seemingly not modern F3s. Smoke kills. A 2020 ‘black summer bush fires’ study in eastern Australia11, estimated bush fire smoke over a three-month period was responsible for 417 excess lives being lost. Recent Californian bush fire data might provide similar findings.

Slow acting foam likely factor in firefighter illnesses

Thirty firefighters, following multi-day attendances at a major 2018 chemical factory fire in Australia12, were reportedly still suffering debilitating illnesses including sudden fainting, headaches, nausea, nose bleeds, fatigue, dizziness, 15 months later. Possibly from toxins, excessive chemical or smoke exposure; likely due in part to the foam’s slow fire control, in Melbourne’s residential Footscray suburb. EPA Victoria confirmed the foam used ‘did not contain PFAS’13 i.e. F3, with reports confirming Alcohol Resistant Fluorine Free Foam was used, appropriate for this mix of chemicals. The biggest fire in decades; it caused 50 school closures, 19 suburbs locked down, took 17 hours gaining fire control14 and five days for F3s to fully extinguish. EPA Victoria confirmed over 2,000 fish were killed15, excessive run-off destroyed the local creek16, with remediation on-going 18 months later. Shouldn’t we expect better outcomes from ‘harmless, environmentally benign’ F3 usage?

Should we risk disregarding the primary purpose of firefighting foams: fast, reliable, effective, and efficient preventatives of wide ranging, potentially ‘disaster making’ scenarios? Undue haste might be ‘courting disaster’?”

Overall incident impacts create unrecognised, increased environmental harm: from slow fire control, excessive smoke, greater breakdown product releases and excess firewater run-off; following prolonged burning. It affects adjacent residents, firefighters, the broader public’s safety, water courses, our environment, but is not adequately considered by legislators; thereby failing society’s expectations.

Performance concerns raised by US Naval Research Laboratory (NRL) and NFPA’s Research Foundation (NFPA-RF)

Comparative NFPA-RF 2020 fire testing18 with five leading F3s required three to four times extinguishment densities of the C6 AR-AFFF control on Mil-Spec gasoline, six to seven times C6 AR-AFFF density on E10 (gasoline with 10 per cent Ethanol added), while exhibiting inferior burn back capabilities. U.S. Naval Research Laboratory (NRL) testing18 gave similar results. Both identified higher application rates, gentler delivery from higher expansion ratios, required using F3s. Reduced throw, forcing firefighters closer to flames and greater wind effects result, with slower fire control and extinguishments. Recent FAA test reports19 showed 90 seconds Jet A1 pre-burn created similar results to gasoline. None of 19 F3s tested on Mil-Spec and ICAO Level C by FAA were able to pass either test (nine commercially available, the rest developmental). Several did not extinguish, some exceeded two minutes extinguishment on Mil-Spec (30 seconds requirement). Others took over three minutes against ICAO Level C’s two minute requirement. Only the best achieved 38 seconds on MilSpec; two minutes 12 seconds on ICAO Level C. Six of nine F3s failed burn back testing. All Fluorine Free Foams (F3s) tested that claimed ICAO C rating, failed to pass that test when run in FAA’s new indoor, state-of-the-art fire test facility. Are such increased risks acceptable? Could we be increasing (not reducing) dangers to public safety, when most expect the duty of fire protection is increased safety.

Performance is crucial to duty of care

Maintaining duty of care, requires performance and speed. Many C8 foam users (including U.S. AirForce) transitioned to reliable, effective ‘drop-in’ high purity, high performance C6 AFFFs, meeting Mil-Spec, U.S. EPA PFOA Stewardship20 and European Regulation 2017/1000 (limiting residual PFOA to low parts per billion [ppb] levels)21. C6 PFAS are proven not bio accumulative, nor toxic, and meet only two of four key criteria required for POP listing. 2013 studies confirmed human half-life averaging just 32 days for the main C6 PFAS marker PFHxA, excreted in urine22, without concentrating in our bodies. Recent U.S. firefighter study identified only legacy C8 PFAS found in 135 firefighter blood serum samples23. PFHxA, was not detected (consistent with 2015 Australian study). Latest U.S. Centre for Disease Control NHANES 2017-18 data24 from 1,929 individuals, also showed no PFHxA detection in blood serum samples, across all age and demographic groups of the general U.S. population. Presumably from its quick excretion in urine after exposure, dramatically reducing risks of harm.

Not all PFAS are harmful

Recent 2021 research confirms only 256 PFAS (including precursors and breakdown products) are commercially relevant globally25. Less than six per cent of ‘theoretical’ 4,730 PFAS substances presented in OECD/UNEP’s 2018 Report. This questions the wisdom of suggesting all PFAS, solids through liquids into gases with widely differing levels of safety concerns, require ‘single group’ regulation, without recognising huge diversity in properties and impacts. It suggests conducting proper regulatory risk assessments according to REACH protocols, on appropriately similar sub-groups, segregating safe from unsafe substances. Why aren’t legislators doing this? The 2021 Federation of German Industries (BDI) position paper26 to the European Chemicals Agency (ECHA) adds support. BDI confirmed: ‘Within the framework of sustainable chemicals regulation, substances that pose uncontrollable risks due to their properties and use profile should be restricted or regulated on the basis of scientific assessments.’ Otherwise ‘… virtually risk-free chemicals will be equated with substances of very high concern (‘SVHC’) with properties requiring regulation… such a classification would represent an incalculable challenge and would have far-reaching negative consequences both for society and for Europe as a business location… BDI is concerned that the restriction of PFAS as currently planned will be disproportionate and unworkable… A lack of viable alternatives to PFAS substances means high socio-economic costs in trying to replace them.’ Such concerns are not limited to Europe, affecting all technologically advanced economies globally, including the U.S.

How does ICAO ‘stack up’ against Mil-Spec?

This becomes especially relevant since most airports globally are regulated under ICAO’s smaller category Level B (rarely Level C) fire test4, not U.S. Mil-Spec2. Some see ICAO’s larger Level C fire test somehow ‘equivalent’ to Mil-Spec, application rate perhaps the only similarity. U.S. Mil-Spec was borne out of three major aircraft carrier disasters (1966-1969) accounting for 206 combined deaths, 631 injured, 36 aircraft destroyed, 40 more damaged, including a severely damaged ship27. Mil-Spec had to ensure such carnage never happened again. It hasn’t, throughout Mil-Spec qualified AFFF’s usage. Might that now change, without such a rigorous, probing, and challenging fire test? Mil-Spec requires rapid extinguishment of seven separate fire test passes to qualify, including fresh and seawater use, half strength and over-strength, dry chemical compatibility, storage stability, longer burn back resistance, plus a host of additional corrosion and environmental testing. It’s tough raising standards to simulate reality.

Time is critical when maximising lives saved”

Such rigor seems absent from ICAO’s Level B and C testing certification, requiring a single fire using freshwater on Jet A/A1 or ‘kerosene’ to pass, without ongoing performance repeatability checks, ever. How is this a ‘duty of care’ for public safety? Particularly when ICAO weakened both Level B and C fire tests moving from 60 to 120 seconds extinguishment in 2014, allowing previously unacceptable lower quality AFFFs and F3s to pass. 2018 saw NFPA 403 relax fire crew response times to two minutes (previously one minute). With three minute survivable cabin atmospheres; aircraft fuel and passenger load projections increasing; busiest airport hubs managing 60-90 seconds aircraft take-off and landing separations and climatic severity growing, why encourage less speed with slower acting F3s? Surely this is a recipe for pending disaster? If the FAA have realised this, why not others? Suppose that involved your loved ones, their lives prematurely truncated? Perhaps partly due to inferior foam ability, how would you, their grieving relatives feel?

Are we considering duty of care during summer’s heat?

Surprisingly, ICAO requires fire testing with air and foam solutions ≥15oC (59oF)4, yet some issued certificates show foam and fuel at 5oC (41oF), in air at 0oC (32oF) still passing, far easier than required. How reliable is that during hot summers? A 2019 Australian Senate Inquiry Report recognised these concerns28, highlighting: ‘the committee was alarmed by the evidence regarding fire-fighting foams, and the fact that the foams in use at Australian airports may not have been tested to Australian standards. The committee notes that ICAO’s international framework for testing foams may not be suitable for the conditions at local aerodromes’. It recommended: ‘CASA (Australia’s Civil Aviation Safety Authority) implement a testing programme for the fire-fighting foams in use at Australian airports, in accordance with ICAO. The testing should take place under conditions unique to Australia (such as higher ambient temperatures), to establish whether the foams operate effectively enough to extinguish aviation fires,’ in the interests of the travelling public’s safety. Still no actions; partly delayed by COVID-19 constraints.

C6 AFFFs could be our best safety compromise?

Growing evidence leads us to conclude FAA’s assessment is correct. High purity C6 AFFFs could be our best compromise; achieving required levels of public safety by delivering fast response during major fires; minimised human health and environmental impacts without compromising public safety. The UK’s Environment Agency in 2014 concluded29: ‘In summary… foam buyers primary concern should be which foam is the most effective at putting out the fire. All firewater and all foams present a pollution hazard.’ A position re-enforced in 201730: The key to preventing worst pollution is have a response plan to clear potential fire hazards … All fire water runoff will be detrimental to the environment if allowed to enter water courses… best technique is to prevent pollution from entering in the first place.’ The FAA confirms: ‘candidate fluorine-free products must be fully evaluated, mitigated, and/or improved before FAA can adopt an alternative foam that adequately protects the flying public.’ Underlining the primary duty of care: keeping people safe; without undue harm. Isn’t it time to re-consider improved safety for everyone before disaster strikes?

Mike WillsonMike Wilson is a firefighting foam and foam systems specialist with over 35 years’ experience of developing, testing, comparing, and reviewing fire performance and environmental impacts of both fluorinated and fluorine free foams, their delivery devices, and integrated fixed systems performances. He was instrumental in developing improved tank fire, bund protection and LNG recommendations in the EN13565-2: 2009 Foam Systems Standard. Wilson also co-ordinated several emergency foam responses to major fire incidents worldwide. An active member of Fire Protection Association Australia’s Special Hazards Technical Advisory Committee, he provides technical advice to a diverse range of stakeholders to better protect Class B flammable liquids with potentially suitable C6 and F3 alternatives. Also, a UL162 Task Group member, reviewing inclusion of F3s into this important approval standard. Wilson’s goal is to ensure life safety and fire protection capabilities are not unintentionally compromised, while achieving more holistic, effective, and practical outcomes to benefit the environment, regulators, and foam users.


1  US Federal Aviation Administration Oct. 2021 – Cert Alert 21-05, Part 139 Extinguishing Agent Requirements, 4 Oct.2021,

2 US Military Specification MiL-PRF-24385F(SH) Amendment 4, 2020 – Fire Extinguishing Agent, Aqueous Film Forming Foam (AFFF) Liquid Concentrate, for fresh and Seawater, April 2020

3 Ian Ross, Jun.2021 – Now AFFF is defunct, what’s the way forward? Industrial Firefighter

4 ICAO (international Civil Aviation Organization), 2014 – Airport Service Manual Doc 9137- AN/898 Part 1, Rescue and Fire Fighting 4th Edition, Chapter 8 Extinguishing Agent Characteristics

5 UK Air Accident Investigations Branch, Jul.2015 – Report 1/2015 on the accident to Airbus A319-131, G-EUOE, London Heathrow Airport 24th May 2013.

6 UK Air Accident Investigations Branch, Aug.2015 – Report 2/2015 on the serious incident to Boeing B787-8, ET-AOP, London Heathrow Airport 12th July 2013

7 Gulf Civil Aviation Authority UAE, 2020 –  Final Report – AAIS Case No: AIFN/0008/2016 Runway Impact During Attempted Go-Around, Air Accident Investigation Sector

8 Singapore Transport Safety Investigation Bureau, 2017 – Final Report into Boeing 777 engine Fire at Changi Airport on 27th June 2016,

9 Galea and Markatos, 1987 – A Review of Mathematical Modelling of Aircraft Cabin Fires, Applied Mathematical Modelling, Vol.11, iss 3, June 1987 p162-176

10 Scheffey et al 1994 – Analysis of Test Criteria for Specifying Foam Firefighting, for Aircraft Rescue and Firefighting, FAA Technology Center,

11 Arriagada, Bowman et al, 2020 – Unprecedented smoke-related health burden associated with the 2019-20 bushfires in Eastern Australia, Medical Journal of Australia

12 The Age, 7 Nov 2019 –  What happened to us in West Footscray? Firefighters call for answers after toxic fire

13 EPA Victoria, 1Sep 2018 – Avoid Stony Creek Water – EPA—epa

14 Metropolitan Fire Brigade (MFB)1Sep2018 – MFB-West Footscray Fire Update

15 EPA Victoria, 3Sep2018 – Keep Pets Away from Dead Fish

16 ABC News 13Sep18 – Stony Creek pollution from warehouse fire ”as bad as it could be”

17 National Fire Protection Association (NFPA) of America,  Research Foundation, 2020 – “Evaluation of the fire protection effectiveness of fluorine free firefighting foams”,

18 US Naval Research Laboratory (NRL-Snow, Hinnant et al), 2019 – Fuel for Firefighting Foam Evaluations: Gasoline v Heptane, NRL/MR/6123—19-9895

19 US Federal Aviation Administration, Sep. 2021 – FAA Research Program, PFAS-Free Foam Research presentation to Research, Engineering and Development Advisory Committee (REDAC).

20 US EPA, 2016 – PFOA Stewardship Program final report of 2015 goals met,

21 European Commission (EU), 2017 – COMMISSION REGULATION (EU) 2017/1000 of 13 June 2017 amending Annex XVII to Regulation (EC) No 1907/2006 of the European Parliament and of the Council concerning the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) as regards perfluorooctanoic acid (PFOA), its salts and PFOA-related substances.

22 Russell, Nilsson, Buck, 2013 – Elimination Kinetics of PerFlouroHexanoic Acid in Humans and comparison with mouse, rat and monkey, Chemosphere 2013 Nov;93(10):2419-25, PMID: 24050716

23 Graber et al, Apr.2021 – Prevalence and predictors of Per- and PolyFluorinated Alkyl Substances (PFAS) Serum Levels among members of a suburban US Volunteer Fire Department

24 US Center for Disease Control and Prevention (CDC), Feb.2021 – Early release: Per- and PolyFluorAlkyl Substances (PFAS) Tables, 2011-2018 (Specifically 2017-2018 PFHxA Data set)

25 Buck, Korzeniowski et al, 2021 – identification and Classification of Commercially Relevant Per- and Polyfluorinated Alkyl substances (PFAS)

26 Federation of German Industries (BDI) Sep.2021 – EU Chemicals Legislation: Restriction of PFAS, Evaluation of envisaged restriction procedure. Position paper,in%20the%20EU%20by%202025.

27 Haze Gray Naval History, 2003 – Carrier Fires, Three Disasters Afloat (USS Oriskany, Forrestal, Enterprise 1966-69)

28 Australian Government 2019 –Senate Rural and Regional Affairs and Transport References Committee “The Provision of Rescue, Firefighting and Emergency Services at Australian Airports”, Aug. 2019,,firefightingandemergencyresponseatAustralianairports.pdf;fileType=application%2Fpdf

29 UK Environment Agency (Gable M), 2014 – “Firefighting foams: fluorine vs non-fluorine”, Fire Times, Aug-Sep 2014.

30 UK Environment Agency (Gable M), 2017 – “The Environmental Impact of Fire Service Activities”, International FireFighter, 22Aug. 2017


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