Frangibility

In order to develop international regulation for the frangibility of equipment or installations at airports, required for air navigation purposes (e.g., approach lighting towers, meteorological equipment, radio navigational aids) and their support structures,[4] the International Civil Aviation Organization (ICAO) initiated the "Frangible Aids Study Group" in 1981, with the task to define design requirements, design guidelines and test procedures.

[5] An overview of the activities carried out to achieve these results is given in "Frangibility of Approach Lighting Structures at Airports".

[6] The missing reference (17) in this article is in "Impact simulation of a frangible approach light structure by an aircraft wing section".

It states that numerical methods can be used to evaluate the frangibility of structures, but that the analytical models should still be verified through a series of representative field tests.

Of all equipment or installations at airports required for air navigation purposes, ICAO has not yet formulated frangibility criteria for the tower structure supporting the ILS glide path antenna, "considering its unique nature", basically: its size.

A plaque marking the frangible section of a London pavement, designed to be broken to release smoke in the case of an underground fire
A sequence of photos showing a frangible bullet fracturing when subjected to high velocity strain waves