SIDs and NPRs
What is a SID?
A SID (Standard Instrument Departure) is a notified route with instructions to provide a link between a specified aerodrome or runway at that aerodrome and a significant point at which the en-route phase of the flight along a designated ATS route can be commenced.
What is an NPR?
NPR's (Noise Preferential Routings) are part of the noise abatement procedures devised by the airport authority. NPR's detail the flight path to be followed by a departing aircraft and are included in SID's. All jet aircraft with a MTOW of 5700kg or more are subject to NPR's. For airfields without SID's, NPR's should be followed after departure.
Purpose of a SID
Segregate traffic operating along different routes and traffic in holding patterns
Provide adequate terrain clearance
Detail procedures in the event of RT failure
Compatible with NPR's
Allow for uninterrupted climb
Allow for the performance of the aircraft
Reduce RT loading
Composition of a SID
Example of a SID from Runway 24 at EGPH:
DCS - The point at which the SID ends and the Flight plan route commences
4 - Validity indicator. Number can be from 1 to 9 and indicates the version number of the SID
C - Route indicator. This indicates the particular runway the SID commences from, and is usually unique for each runway within a TMA.