'One degree' change behind ADIZ trouble
December 3, 2013, 12:08 am TWN
TAIPEI, Taiwan -- The International Civil Aviation Organization (ICAO) aimed at facilitating air traffic control when it expanded the Taipei Flight Information Region one degree east in 1955, but the move also caused “trouble” for Taiwan's aviation authorities.
Civil Aeronautics Administration (CAA) official Feng Ying-pin said Monday that when ICAO demarcated Taiwan's flight information region in 1953, its easternmost border was longitude 123 degrees east.
Since the aircraft of the time climbed slowly, Taiwanese planes flying to Japan usually could not reach a level altitude before they reached the barrier, forcing them to hand air control operations over to Japanese authorities.
Feng said that in consideration of the difficulty presented for air control operators, ICAO moved the eastern part of the flight information region one degree to 124 degrees east in 1955 — which happened to be inside Japan's air defense identification zone.
A country's flight information region and its air defense identification zone (ADIZ) are usually identical, he said, but the ICAO's changes make the situation for Taiwan and Japan “special.”
The overlap has caused trouble for the CAA, he said, as Japan's Self-Defense Force heightens its alert whenever a Taiwanese aircraft passes through the overlapping areas.
In 2002, for example, Japanese defense aircraft caused radio interference for a Taiwanese plane testing a new air route through the area.
The CAA used diplomatic channels to ask Japan not to interfere with civil aircraft that had made applications to pass through the overlapping zone.
The opening of direct flights between Taiwan and China several years later made matters more complicated, as one flight path designated B591 travels through the area.
Taiwan has complied with Japanese instructions to give flight plans for all civilian craft flying through the zone since 2009.