page_title: Warsaw radio mast
section_title: Collapse
hierarchical_section_title: Warsaw radio mast / Collapse
caption_attribution_description: The Warsaw radio mast which was the world's tallest structure until its collapse in 1991.
context_page_description: The Warsaw Radio Mast was a telecommunications tower located near the town of Gąbin, central Poland, and the world's tallest structure at 646.38 metres from 1974 until its collapse on 8 August 1991. It was the second tallest structure ever built, being surpassed as the tallest by the Burj Khalifa tower in the United Arab Emirates, completed in 2009.
  Designed by Jan Polak, its construction started in July 1970, was completed on 18 May 1974, and its transmitter entered regular service on 22 July of that year. The tower was used by Warsaw Radio-Television for longwave radio broadcasting on a frequency of AM-LW 227 kHz before 1 February 1988 and 225 kHz afterwards. Its base was 115.2 metres above sea level. Because a voltage potential of 120 kV existed between the mast and ground, it stood on a 2-metre-high insulator. It operated as a mast radiator, so its height was chosen in order to function as a half-wavelength antenna at its broadcasting frequency. The signals from its 2 megawatt transmitters could be received across essentially the entire globe. Its weight was debated; Polish sources claimed 420 tonnes.
context_section_description: At 16:00 UTC on 8 August 1991 a catastrophic failure led to the collapse of the mast. The mast first bent and then snapped at roughly half its height. The helix building and the transmitter building (including the transmitter devices in it) were not damaged. The construction coordinator and the division chief of the company which built and maintained the mast were found liable for the collapse, and both were sentenced to two years in prison.
  Since the collapse of the Warsaw radio mast, the tallest structure in Poland has been the FM radio and TV transmission mast at Olsztyn-Pieczewo, measuring 360 metres (1,180 ft)
caption: On 8 August 1991 at 4pm UTC the mast collapsed. It is pictured here in January 1992.
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