Eventually, there appeared a formula for determining agent quantities and it became an international standard that exists even nowadays. The principle idea of this formula is based on the fact that fuselage integrity must be kept unchangeable to provide the survival of passengers or crew members. The tests demonstrated that it could be done only by keeping fire at least 50 feet away from fuselage and that people could have less than a minute to save themselves and to cope with the fire. These standard data were projected to different types of aircraft of different size. It is quite natural that one need a very good knowledge of the subject and a great experience to make such calculations as well as one must test it in order not to make a mistake. That is why specialists decided to classify all aircraft to avoid this problem that any airport could have. Thus, all aircraft were grouped into eight categories and since that time and now on the length of fuselage has become the principle factor that has replaced gross weight.

Nowadays one of the main problems that scientists and engineers try to resolve is the problem of the safety of fire fighters, the safety of our environment and nature and, finally, the last but not the least problem is the problem of water waste. Engineers work on different apparatus that could correspond to all characteristic mentioned above. Among the latest machines we can name Aqueous Film Forming Foam (AFFF) extinguishing systems, a No Foam Kit and others. As for AFFF extinguishing systems we can say that current design standards include both overhead and low level AFFF extinguishing systems. The overhead AFFF system typically consists of standard closed head sprinklers that are zoned within areas defined by draft curtains. In some existing installations, the overhead systems are open head deluge systems the low level system typically consists of multiple high flow monitors. The low level AFFF and overhead deluge sprinkle systems are activated by separate detection systems.

Due to high cost incurred from damage of aircraft and electronics resulting from accidental discharges of the overhead AFFF system, researchers are exploring alternate suppression techniques. They propose the approach that would replace the overhead foam suppression system with a closed-head water sprinkler system and it would permit to minimize the time delay in activating the overhead system through the use of quick response sprinklers. At the same time test showed that a low level AFFF system alone could achieve rapid fire control and extinguishment without the use of overhead sprinklers.