SIDSTARS

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1 SIDSTARS

SIDSTARS

What are they, Where do you get them, How do you use them.

Introduction

SIDSTARS is an acronym of acronyms, SID (Standard Instrument Departure, more correctly referred to as a Departure Procedure (DP) in the US) & STAR (Standard Terminal Arrival Route) are procedures published by an air traffic control agency responsible for air navigation in each jurisdiction. SIDSTARS procedures developed for PMDG use also include one more acronym: IAP (Instrument Approach Procedure). The scope of this article includes an overview of the role that these procedures play in navigation, a brief description of where they are found in your system and the source for updates; however, the focus of this article is how to use them.

This is not a lesson on how to create or edit procedures, please refer to Terry Yingling's excellent tutorial located at http://planepath.com. The information will presume US procedures published by the FAA National Aeronautical Charting Office (NACO) unless specified otherwise.

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What Are They?

SID, STAR and IAPs are procedures developed through a very institutionalized process to provide for safe navigation to and from airports (referred to as terminal procedues although some procedures may extend into the enroute environment by hundreds of miles). The SID and IAP procedures ensure adequate separation between the aircraft and obstructions during the initial and final stages of flight, and have been test flown by special FAA flight check aircraft to ensure that hundreds of hours of desktop studies actually work in the real world. SID and STAR procedures primarily serve to provide an airspace structure for safe and efficient control and separation of traffic. The Aeronautical Information Manual is a good reference for basic information on all things related to flying (required reading for all student pilots: http://nwp.natca.net/Administration/Documents/Airtrafficpublications/AIM/index.htm ) defines the charts that are available for each procedures thus:

(a) Instrument Approach Procedure (IAP) Charts. IAP charts portray the aeronautical data that is required to execute instrument approaches to airports. Each chart depicts the IAP, all related navigation data, communications information, and an airport sketch. Each procedure is designated for use with a specific electronic navigational aid, such as ILS, VOR, NDB, RNAV, etc.

(b) Instrument Departure Procedure (DP) Charts. DP charts are designed to expedite clearance delivery and to facilitate transition between takeoff and en route operations. They furnish pilots' departure routing clearance information in graphic and textual form.

(c) Standard Terminal Arrival (STAR) Charts. STAR charts are designed to expedite ATC arrival procedures and to facilitate transition between en route and instrument approach operations. They depict preplanned IFR ATC arrival procedures in graphic and textual form. Each STAR procedure is presented as a separate chart and may serve either a single airport or more than one airport in a given geographic area.

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Where To Get Them

SIDSTARs files are currently available from three sources. The primary source for global coverage (as of Aug 2007) is available from Navigraph (http://ndac.navigraph.com/www/fmsdata.asp) as part of the purchase of AIRAC data (see discussion on difference between AIRAC and SIDSTARS below). A popular choice for US & UK procedures is provided free by Terry Yingling at his Planepath (http://planepath.com) site. Users download an executable that, when run, will place current SIDSTARS text files in the .../PMDG/SIDSTARS directory without deleting locations not included in his collection. These procedures are derived from data with minimal editing and customization. The third source are contributors who upload individual and collections of SIDSTARS text files to various on-line libraries such as the AVSIM FS2004-Flight Plans. Dan Downs provides all the major US location procedures in this library, which are updated every cycle and have many custom features not found in others such as complete routing for departures and arrivals for use in a non-ATC environment. To find his current collection, perform an AVISM extended library search with Author=Dan Downs then sort the results by date.

Richard Stefan's NavData (http://navdata.at) recently quit providing the ability to upload new PMDG procedures to his site, but if currency is not an issue there are still many locations created by individuals and uploaded for sharing. However, mixing different cycles of AIRAC and SIDSTAR data will not work at locations that have had changes such as runway renumbering or navaid changes.

All SIDSTARS procedures rely on a second source of navigation data referred to as AIRAC data (also called NAVDATA), which is a database of airport, navaid and fix locations and airways. AIRAC data is released every 28 days, and is obtained for a small fee from a commercial provider that Richard Stefan allied with after the availability of free global data evaporated Oct 2006: navigraph.com (FMS Data). The AIRAC data is required by the PMDG FMS to resolve the location of runways, ILS frequencies and final approach courses used by SIDSTARS procedures. This data is stored in either the .../FMCWP (FS9) or .../PMDG/NAVDATA (FSX) directory. Although not free, the cost is nominal (about US$ 2.60 / cycle with unlimited downloads each cycle), which covers the cost of purchasing the data and translating it into different aircraft simulator formats. As a footnote, AIRAC Cycle 0609 is still available at no cost and will work with most current SIDSTARS except locations such as KSEA Seattle-Tacoma, KATL Atlanta or KORD O'Hare Chicago where runway numbers have changed.

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Where Are They?

The PMDG installer creates two locations within your default flight simulator directory that are used to store navigation data. The location also depends on platform (FSX or FS2004):

FS2004:

The subdirectory FMCWP (for example: c:\Program Files\Microsoft Games\Flight Simulator 9\FMCWP) contains AIRAC data, which is the global database of airports, navaids, waypoints and routes. Everything that the FMC knows about the world is based on this data, which is completely independent of the MSFS world. SIDSTARS procedures also rely on this data for the location of navaids and runways. This is always a good place to start looking if you get a FMC error such as "RNW 09L Unknown" or "KEG Unknown." All procedure references to navaids and rnws are external references that rely on the AIRAC data.

The PMDG installer also creates the subdirectory PMDG (for example: c:\Program Files\Microsoft Games\Flight Simulator 9\PMDG) where one step down the SIDSTARS directory is located, and where all the SIDSTARS procedure files are stored. Each procedure file is a text file where the file name uses the ICAO four-letter identifier for the airport (such as "katl.txt" for Atlanta Hartsfield Intl). The text files are read by the FMS at the time that you enter the origin and destination airports into the RTE page (page 1).

FSX:

The AIRAC data in stored in the subdirectory NAVDATA under the PMDG folder (for example: c:\Program Files\Microsoft Games\Microsoft Flight Simulator X\PMDG\NavData).

The SIDSTARS are stored in the subdirectory SIDSTARS under the PMDG folder (for example: c:\Program Files\Microsoft Games\Microsoft Flight Simulator X\PMDG\SIDSTARS).

If you use both platforms, the information needs to be duplicated in both locations.

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How To Use Them

The three basic parts of a flight plan are departure, route and arrival. The PMDG FMC requires a departure runway as a prerequisite for the PREFLIGHT COMPLETE message (737NG); however, route and arrival are optional. Actual instrument flight plans generally include all three elements but this varies by location. For example, the world's busiest airport (KORD) doesn't have established DP routes (ORD DP is a "generic vectors" departure procedure that provides basic instructions but not specific routes) but most locations flown by commercial carriers have a variety of DPs designed for the specific environment of the location. The arrival is included in a typical flight plan, but the specific approach procedure is not because it is not known until assigned (or provided in an "expect clearance") by the approach controller on initial contact. All instrument flight plans filed via computer (such as DUATS) will require a first and last fix for the route that are recognized as transitions between the low and high route structure, regardless of whether a DP or STAR is named in the plan. Some DPs and STARs are runway dependent, so the dispatcher or pilot submitting the flight plan request may have to make an educated guess and anticipate the departure runway or arrival approach. This is expected and if there are changes ATC will admend your clearance when required.

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Departure Procedures

In general, a departure procedure consists of a method to reach a departure fix and transitions from that fix to a first enroute fix. The "after takeoff" procedure for each runway, minimum climb requirements and obstacle warnings are found on the DP chart, as well as a host of other useful information (ATIS, Clearance Delivery, Ground, Tower and Departure frequencies for example). A generic vectors DP chart contains this information and it spares ATC from having to communicate redundant information in every clearance. It's common to file without naming a DP only to have Clearance Delivery provide the named generic vectors DP as part of your clearance for this reason. The more complex DPs have "after takeoff" procedures and RNAV-based routes (GPS or RNP) for each runway to multiple transitions (e.g., KDFW or KLAS have elaborate RNAV procedures). Regardless of the DP filed or received from clearance delivery or dispatch, the takeoff instructions from tower have precedence in the real world. Flying the DP starts at about 400 agl, which is the minimum altitude at which any procedure is designed to provide obstruction clearance; therefore, always maintain runway heading until 400 agl. Above 400 agl, normal procedure is to engage CMD LNAV/VNAV modes to allow tracking (or HDG mode if on ATC vectors) while the priorities of flying are satisfied. Important note: many DPs will include altitude constraints that keep you above or below other traffic flows, not complying may be very hazardous to your health or career. In most cases, handoff from Tower to Departure will occur as soon as you are clear of the local controllers area of responsibility (pattern altitude), so have that frequency ready in the standby. Also in most cases, your clearance included a "climb and maintain.... expect requested altitude in 10 min," altitude constraint. The altitude restriction is probably the limit of departure control's airspace, and you may expect to be cleared higher when handed off to Center, which often happens above a specific altitude (10,000 - 14,000 in most cases).

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Arrival Procedures

In general, an arrival procedure consists of a transition from an enroute fix to an approach fix sometimes called an approach gate. Top of Descent (TOD) may occur either well before or after the the beginning of the STAR transition. Some STARS have altitude constraints such as "at or below FL240" in a transition, which is intended to separate your descent path from other enroute traffic. Many STARS have a single altitude constraint at the approach gate, which is where you are handed off from Center to Approach Control. There are also STARS with many constraints to separate arrivals from departures. Regardless, it is very important to verify the FMC LEGS information with the STAR procedure before you get to the TOD to ensure that the constraints are properly coded and your TOD is correctly anticipated. It is just as important to comply with your ATC clearance: STAR constraints are secondary to your clearance, which may start you down sooner or latter than anticipated and also set speed constraints for traffic flow. It's a sign that things are going smoothly when your clearance is simply to comply with the STAR. Most arrival procedures are simply transitions between an enroute fix and the approach gate, followed by ATC vectors for an IAP; however, there plenty of locations where the opposite is true and the STAR continues all the way to the IAP, and to multiple IAPs serving different runways. It is the latter that the PMDG FMC programming hasn't accomodated yet, and get lost in DAFIF translations. When a STAR branches after the approach gate to route flow to different runways, the procedure author has a choice of either creating multiple versions of a STAR or adding the arrival routes as transitions within the IAP. It is beyond the scope of this article to discuss the pros and cons of each method; however, it is mentioned because it is necessary to understand the implementation that the procedure author has selected. If the STAR exists in different variants depending on runway, then it will appear multiple ways in the FMC index of arrivals (e.g., BOIJD.N BOIJD.S for landing north or south direction, or custom routes will be listed as CIVET.25L for landing ILS25). If the arrival transitions are encoded in the IAP arrivals, then only one instance of the STAR will be found in the FMC index of arrivals, but each IAP will have a transition (usually same name as the arrival name) that is the arrival transition located in an approach instead of an arrival (e.g., ILS25L.CIVET where CIVET is the arrival transition included in the ILS25L IAP for KLAX).

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