Study on the frangibility of airport approach lighting towers

A series of full-scale impact tests on approach lighting towers, used at Canadian airports, was conducted to provide information on tower response. These data were necessary for the development of simplified requirements and test methods for the design of frangible structures which will minimize the impact hazard to aircraft. Impact testing was performed on the Canadian tower, which is a lattice type structure using both rigid and representative wing impactors at high, medium and low impact speeds. The representative wing section was fabricated to duplicate the outer wing section of a Piper Aztec aircraft. Two specimens of the towers were tested at each impact speed for both the soft and rigid impactors striking the tower at both the apex and the side of the triangular cross-section for a total of 24 tests. High-speed video cameras and a 16 mm high-speed camera were used to record the impact sequence, the mode of failure and the contact time between the impactor and the tower. The influence of impact speed and impactor type on the maximum impact force, energy to fail the tower, energy to maximum force and energy over the contact period was studied and compared to test results using other tower structures.