Standard Instrument Departure

Standard Instrument Departure (SID) routes, also known as "Departure Procedures" (DP) are published flight procedures followed by aircraft on an IFR flight plan immediately after take-off from an airport.

Assignment procedure

A SID is usually assigned by air traffic control to the pilot based on the destination (or actually, the first waypoint in the flight plan) and the active runway. A standard instrument departure procedure consists of a number of waypoints or fixes, which may either be given by their longitudinal and latitudinal coordinates or which may be radio beacons such as VOR or NDB beacons and a radial headings. It also includes a climb profile, instructing the pilot to cross certain points at or above a certain altitude. A SID procedure ends at a waypoint lying on an airway which the pilot will follow from there.SID procedures are defined by the local authorities (governments, airports and air traffic control organizations) to ensure safety and expedite handling of departing traffic and - when possible - to minimize the amount of noise over inhabited areas such as cities.

Naming of SID procedures

Naming conventions for SID procedures vary by region.

In most of Europe, SID procedures are usually named after the final waypoint ("fix") of the procedure, which often lies on an airway, followed optionally by a version number and often a single letter. The version number starts at 1 and is increased each time the procedure is altered. The letter designates the runway: the route flown to a particular fix depends on the take-off runway. For example, at Amsterdam airport Schiphol departure routes are published to the GORLO radio beacon from where the "(U)L980" or "(U)P20" airways can be joined. The SID to GORLO corresponding to runway 09 is named "GORLO1N" (pronounce "GORLO One November"); aircraft departing from runway 36L will fly the "GORLO2V" departure ("GORLO Two Victor") instead.All SIDs from runway 09, for example, to other waypoints will also end in the letter "N".

In the United States, SID procedure names are less rigidly formatted, and may simply refer to some notable characteristic of the procedure, a waypoint, or its geographical situation, along with a single digit that is incremented with each revision of the procedure. Thus, the LOOP3 SID at Los Angeles International Airport was so called because it was the third revision of a procedure that required aircraft to take off towards the west, over the ocean, and then make a roughly 180-degree turn back towards the mainland (a loop, in other words).

Deviations and separation

Though SID procedures are primarily designed for IFR traffic to join airways, air traffic control at busy airports can request that VFR traffic also follows such a procedure so that aircraft separation can be more easily maintained. Usually VFR pilots will be given radar vectors corresponding to the SID lateral route with different altitude restrictions.

Pilots must follow the published SID route. Small deviations are allowed (usually there are "flight paths" of some kilometers wide) but bigger deviations may cause separation conflicts. Pilots can be fined for too large deviations from the prescribed path.

The precision of SIDs also varies by region. In some countries and regions, every detail of the lateral and vertical flight path to be followed is specified exactly in the SID; in other areas, the SID may be much more general, with details being left either to pilot discretion or to ATC. In general, however, SIDs are quite detailed.

Example of a SID

This section gives an example of a current (November 2006, [http://www.ais-netherlands.nl/aim/060720-060831/eAIP/html/index-en-GB.html] ) Standard Instrument Departure for Amsterdam airport Schiphol, The Netherlands.

* "Lateral route": Track 222° MAG. At 500 ft AMSL turn left (turn MAX 220 KT IAS) to track 085° MAG. At PAM 223 turn left to intercept PAM 207 inbound PAM VOR to intercept PAM 016 to ANDIK (25.2 PAM).
* "RNAV (sequence of relevant waypoints)": THR 22 / At 500 |ft AMSL turn left / EH065 (MAX 220 KT IAS) / EH066 / PAM / ANDIK
* "Vertical": Cross ANDIK at FL 060 (or above if instructed by ATC)
* "After departure" Contact Schiphol Departure when passing 2000 ft AMSL, climb to FL 060.

ee also

* Standard Terminal Arrival Route