The International Civil Aviation Organisation (ICAO) has said the airline industry agreement on a standard measure of aircraft greenhouse-gas emissions may be delayed at least a year for more research, Bloomberg has reported. "Standards, not to mention the broad consensus which effective ones require, take time to develop," said spokesman for ICAO in Montreal, Anthony Philbin. "The present timetable looks to it being more fully resolved by end-2014 or possibly sometime in 2015." ICAO's Committee on Aviation Environmental Protection proposed using a plane's maximum take-off weight (MTOW) to help gauge aircraft emissions and efficiency, the regulatory body said in July. The ICAO council was expected to approve the system this year, it said at the time.