Foaming of Runways for Emergency Landings

The procedure of foaming runways was previously done extensively in the military environment and occasionally for commercial aircraft. It was one of the best pre-planned practices for emergency landings (aircraft with belly landings or with defective nose gear) on runways to mitigate damage to the aircraft and reduce the likelihood of fire which occur following the impact. Some of runway foaming operations were most successful, whereas some operations did not, as the emergency landing aircraft missed or overran the foam blanket.

  There are mainly four theoretical benefits of runway foaming i.e. aircraft damage reduction, deceleration forces reduction, minimize friction spark hazard and reduction in fuel spill fire hazard. Successful runway foaming operation depends on many factors. i.e. the design of the aircraft, the skill of the pilot, the type and condition of the runway surface, the landing mass of the aircraft, the weather, the temperature and the visibility conditions etc.

  Runway foaming initiation request to foam a runway for an emergency situation is a flight operational decision. Therefore the request to take such action should always come from the pilot-in-command of the aircraft or the aircraft operator, assuming that they are familiar with all the considerations of runway foaming. Determination the feasibility of applying foam to a runway at a designated airport is a decision which the airport manager or representative must make in consultation with the officer-in-charge of the Airport Rescue and Fire-fighting Service (ARFF) after receipt of the official request for such services.

  There are many operational problems for runway foaming, which should also to be evaluated to determine the feasibility. i.e. the time element available for accomplishing the production and distribution of the foam over the runway; the wind and visibility conditions; the foam-making capability and adequacy of the equipment available on the airport for runway foaming; the effect the foam laying and clean-up operations; the ambient weather conditions. Heavy rain or snowfall conditions and the length of the runway and the nature and condition of the runway surface, as runway slope and runway surface temperature will also affect the foam water drainage time.

  A number of well executed emergency landings on foam-coated runways have been accomplished with minimum damage to the aircraft. But on the other hand studies had shown that in the similar type of aircraft emergency landings where foam was not applied on the runway, no major fires occurred and the damage sustained by the aircraft was moderate.

  It is to be mention that, the newer types of foam are not suitable for use in this operation and therefore this procedure currently is not widely used. Fluro-protein foam, Film forming fluoro-protein foam and Aqueous film forming foam (AFFF) are not considered suitable for runway foaming operations due to their short drainage time. The International Civil Aviation Organization (ICAO) Airport Services Manual, Part 1 – Rescue and Fire Fighting (Doc 9137-AN/898) Third edition in1990 provided procedures in Chapter 15, as Foaming of Runways for Emergency Landings which emphasize over the use of the Protein Foam along with the required spreader equipment by the airport operator. In 1966 the U.S. FAA recommended foaming runways for emergency landings, but withdrew that recommendation in 1987. Similarly, ICAO also excluded the Chapter for Foaming of Runway for Emergency Landings on the next edition of Doc 9137-AN/898 i.e. Forth edition in the year 2015.

  As now a days maximum airports are not using protein foam, so in practical runway foaming operation becomes the least effective. The pre-foaming of runway would also deplete fire-fighting foam supplies in the event they were actually needed to respond to a fire. Moreover foam on the runway may decrease the effectiveness of the landing airplane's brakes, possibly leading to it overshooting the runway. Moreover the environmental risk of certain firefighting foams began to be recognized in the early 2000's, which also become a reason against the runway foaming practice.