Problem:
                    Expanding air traffic requires large hangars, terminals etc. on airports
                    Constructional activities require a number of assembled cranes
                    Typical height up to 50 to 70m or even higher
                    Typical length of the jib up to 50m or longer
                    Close distances to the runway, but outside the critical and sensitive areas
                    Illuminated by the horizontally polarized navaids and landing systems
                    Rotating jib is a highly transient and effectively scattering object

Observations/Measurements:

DDM-distortions of large cranes (can) exceed the CATIII specs on the runway
Incidents are reported for a destruction of the capture ratio on the entire runway
Effects are reported in the clearance intercept region of dual frequency ILS
Highly transient effects and difficult to measure
Requires coordination of jib positions
Worst case superpositions of some cranes occur, but rarely
Wind safety rules for the cranes support the worst case occurence