While supportive of the reduced vertical separation minima concept in China, the International Federation of Air Line Pilots' Associations believes the use of metric measurements is "inappropriate" in certain areas of operation.
"As the use of different altimetry units seriously affects flight safety, only one unit should be used for altimetry," IFALPA says. "The foot is by far the most commonly used unit for reporting vertical position and vertical intervals and lends itself to a simple rational system of cruising levels."
IFALPA is urging China to conduct a collision-risk assessment not only for its own airspace, but also for the transition airspace with flight information regions of adjoining territories, adding: "We would request China to review their operations using metric altimetry and adopt the use of the foot for implementation of RVSM."