Meteorological Masts

Pollite Masts are fully ICAO and FAA Approved

In 2006, the frangibility and deflection/wind speed requirements of approach lighting masts and other obstacles were more clearly defined with the publication of the ICAO’s Aerodrome Design Manual, Part 6 Frangibility.

A manual designed to be read in conjunction with Annex 14 but offering clearer guidance on the design, testing and installation of frangible structures at airports. Frangible objects, as defined within the manual were to be of a low mass and designed to break, distort or yield on impact presenting a minimum hazard to an aircraft.

Annex 14 Vol 1 Chapter 9 specifies in detail the equipment and installations of operational significance on the airfield which should be frangible, including:

• Any visual or non visual aid located near runways, taxiways and aprons.
• Any obstacle located on an area intended for the surface movement of aircraft or that extend above a surface intended to protect an aircraft in flight.
• Any structure that presents a hazard to aircraft in the event of accidental impact during landing, take off or ground manoeuvring. Including:
  • Elevated runway, taxiway and stop way lights
  • Approach lighting systems
  • Wind Direction Indicators
  • ILS equipment
  • Anemometers

The manual also sets out a general expectation for testing of frangible masts including procedures and acceptance or rejection criteria.

• The structure should Break/Distort/Yield when subjected to the sudden collision forces of a 3000kg airborne aircraft travelling at 140km/h or on ground at 50km/h.
• The structure on impact should not become entangled with the aircraft affecting its maneuverability.
• The structure should not impose a force on the aircraft in excess of 45kN
• Maximum energy imparted as a result of the collision should not exceed 55kJ
• Design of the mast should take into consideration that individual components should be at the lowest mass possible
• Full consideration should be given to cabling and its segmentation.

FAA Advisory Circular No. 150/5345-45C Low Impact Resistant Structures

As with ICAO the FAA issued in March 2007 an advisory circular with their own specifications for frangible masts used to support approach lighting systems. With specific regard to frangibility the FAA circular follows the same frangible design goals as ICAO’s Design Manual.