The incidence of falling objects and measures to combat it
There have been a number of incidents involving ice and aircraft components falling from aircraft in the area surrounding Narita Airport (NAA). Activated landing gear is considered to be one of the causes for falling ice. In view of this, arriving aircraft on a southerly approach have been instructed to lower their landing gear over the ocean since 1991. Airline companies were officially instructed to observe this ruling with its promulgation in the Aeronautical Information Publication since 1993. Since May 1995, this instruction has also been included on the Automatic Terminal Information Service (ATIS)
NAA conducts spot inspections over four 7-day periods each year to monitor adherence to the instruction that landing gear on approaching aircraft be lowered over the sea. In February 1998, a survey was conducted into ice on arriving aircraft by the Committee on Falling Aircraft Objects comprised of delegates from the Ministry of Transport, NAA and the airline companies. As a result of that survey, airline companies were instructed to fit drainers inside all water supply pipes and to inspect all drainage systems for leaks. The Ministry of Transport requested two airline manufacturers to undertake studies into structural improvements on their aircraft and notified to that effect to the governments in the countries where those manufacturers are based.
bron: Narita Airport Japan