General ICAO/FAA

A Background to Airfield Frangibility

The FAA initiated investigations into the relevance and effectiveness of frangible structures on airfields in 1976 and this research has continued up to the most recent releases from the FAA and ICAO in 2005-2006. Over the thirty years of research the importance of frangibility as a safety benefit on the airfield has been clearly recognised.

Research collated by the Airline Pilots Association (ALPA) from between 1959 and 1986 revealed that from 1002 incidents studied the most common incidents were overruns, veer-offs and undershoots. A common factor in all was the involvement of fatalities and the aircraft coming into contact with an obstruction. In 1981 ICAO established the Frangible Aids Study Group to look into improving the frangibility of obstruction and the resulting safety of the airfield.

More recent detailed studies show that from 1995-2004 71% of jet aircraft accidents occurred during landing and takeoff*. The most common occurrences remain undershoots, veer off and overruns. Although incredibly rare (2 in every 10 million*) the latter remained the most prevalent. Whilst a great deal of research and development into the runway safety area has taken place, irrespective of incident, the likelihood of contact with obstacles on the airfield remains high.

The potential problems of aircrafts striking obstacles remained however ICAO recognised that fatalities and aircraft damage could be significantly reduced by improving airfield design and introducing frangibility as a requirement for airfield obstacles. ICAO Annex 14 vol1 2nd edition 1995 gave a clearer definition and expectation of frangible objects and the subsequent publication of ICAO Aerodrome Design Manual,Part 6.Frangibility offered a new clear directive towards frangible airfield obstacles.

*US Transport Research Board Aircraft Overrun Database 1980-1998