Standard Instrument Departures (SIDs) and Standard Instrument Arrivals (STARs) provide a safe and efficient way of prescribing a large amount of information through procedure design. Both depict the lateral profile of an instrument departure or arrival route and the associated level and speed restrictions.
The use of SID/STAR phraseology brings significant benefits. It enables efficent and concise communication. It allows ATC to issue, and aircrew to understand detailed clearance information that would otherwise require long and complex transmissions.
Over time though, these benefits have been eroded. The development of non-harmonised practices induced that different meanings would become attached to certain elements of SID/STAR phraseology. Confusion crept in. Pilots became uncertain of what air traffic controllers meant. Extra questions and request for clarification appeared on frequencies that were already cluttered.
This increased safety risk called for a renewed effort, to strenghten and harmonize the SID/STAR phraseology.
So what is new ?
And what doesn't change?