On the Müggel Mountains in Berlin one planned in 1954 to build a 130 metre tall TV tower. Unfortunately after construction work started, one discovered, that it would endanger air traffic and so work was stopped in Decmber 1955 as it reached a height of 31 metres ( complete article on
http://en.wikipedia.org/wiki/Berlin-...berge_TV_Tower ).
This was not the only case, that one discovered at construction time, that it would endanger air traffic. At the beginning of the 1960ies at Bergheim, a village north of Salzburg, Austria, the erection of two 200 metre tall mast radiators for a new mediumwave transmitter for the Salzburg area was ceased, as one found out, that they would endager air traffic. Nevvertheless work of transmitter building has already started. ( Source:
http://members.aon.at/wabweb/frames/radioaf.htm )
Who knows further examples?