Gary McDowall of foam supplier ABC Macintosh
Published: 01 October, 2008
The Civil Aviation Authority (CAA) has launched an international research initiative to develop improved aircraft fire fighting foams. The physical and chemical behaviour of foams is crucial in fire management and this research has been initiated by the CAA on behalf of the International Civil Aviation Organisation (ICAO). This research will also allow a review of more recent developments in foam chemistry which would include more viscose foams such as those formulated with gum, more commonly associated with alcohol resistant fuels but not permitted within the current ICAO standards.
The research has two specific aims. Firstly, to establish foam testing methods for a reliable protocol with a view to develop an improved international regulatory standard for more efficient foam concentrates. Secondly, to assess if more efficient foams can help reduce the overall volumes of both water and foam concentrate required on airport crash rescue vehicles (ARFF), which in turn could reduce the size of the vehicles currently in service at airports.
There is little argument that this research is important and with more than 30 years since the development of the original standards, one could say this research is overdue. Given that the wheels of organisations writing standards turn very slow and more understandably with an international standard such as ICAO, one could argue that this research could and should have encompassed so much more than just foam concentrates.
As a founder member of the International Aviation Fire Protection Association (IAFPA), I was fortunate to be around when the idea of a new ICAO performance standard was first being discussed in IAFPA circles some four years ago. At that time, the entire premise of a new standard was about reducing the costs of crash rescue vehicles.
The financial pressures on airport owners and operators four years ago have only increased in today’s uncertain financial climate and driving down costs will continue to be an essential part of their business model. Airport fire service’s are quite often regarded as the ‘none value added’ element of airport operations and always under the managements microscope. It is the cost of replacing or refurbishing airport crash rescue vehicles that have caused shivers down the spine of any airport owners for many years.
So the question being posed in 2004 was, “Could the cost of these essential vehicles be reduced?”. The discussion was focused on how to significantly reduce the amount of water and foam being carried on the vehicles but still achieve acceptable extinguishing performance. One of the ways to achieve this was to investigate the foam delivery systems available today and not freely available 30 years ago.
Compressed Air Foam (CAF) systems were known to function with far less water and foam but could not generate the volumes of air required to produce a finished foam for a large category 9 (CAT 9) airport. However, it was felt that this type of system could operate at lower category airports and that investigations should be undertaken to fully understand the limitations of CAF given that the reduction in weight of both water and foam could offer the possibility of ARFF vehicles being lighter, on a smaller chassis and more affordable for smaller airports operating between CAT 4 and CAT 7. This is how I recall the concept of developing a new ICAO performance standard to be known as “ICAO performance level C”. In fact there were initial trials undertaken at a Midlands Airport fire training facility using a small scale CAF system but never developed further with any true conviction.
My personal view is that this new research is an opportunity missed. The CAA/ICAO tests being undertaken at the CNPP test facility in France are simply looking at a foam’s performance on a larger fuel tray (233B as described in EN3-1), with similar extinguishing times and performance to that of an ICAO level B foam, using existing and established test delivery equipment. Even if foam concentrates can perform to this new test protocol, those concentrates are likely to contain higher levels of fluorosurfactant to meet the required extinction times and will be far more expensive than the established ICAO Level B foams we have today. More importantly, foams that can extinguish and meet the proposed ICAO level C standard are unlikely to provide any significant reduction in total water requirement that would result in lighter and less costly airport crash rescue vehicles.
Hopefully, in the not so distant future, the CAA and ICAO will adopt a more pragmatic approach when researching improvements to extinguishing fire with foams and embrace not just the developments in chemistry but the technical advances in foam delivery equipment. Researching the combination of both the chemical and technical advances is more likely to achieve the original ideas of a new ICAO standard. Significantly lower volumes of water and foam, lighter vehicles with new delivery techniques, sounds too good to be true for airport owners and operators. It will take a more radical approach by the industry regulators to make this work. But this type of approach can work. It has worked for many of the civil fire and rescue services and is working every day in many parts of the UK. Surely it deserves more serious consideration for research and development for aviation applications.
