SIDs and STARs

 

SIDS AND STARS

by Mike Brady

BACKGROUND 
When an aircraft flys from airport to airport using IFR, they do so by flying along standard routes marked on published (printed) charts, often available to the general pilot population for a fee (see VATSIM Chart Center∞). These 'airways' are like roads in the sky and are drawn between points which are given names so that anyone planning to make a flight can get from A to B in a controlled and structured manner instead of just flying whichever way they please. The advantage of this is that once a pilot has declared his intended route (by filing a flight plan) air traffic controllers do not have to give vectors and instructions all of the time - the pilot has promised to fly a certain route and will stick to that route barring complications of weather or other air traffic in the way. These routes effectively join every airport in the world to each other via known pathways. 

Some routes are called 'Jet Airways' and generally are for jet aircraft flying at a high altitude. There are other routes called 'Victor Airways' which are for lower flying aircraft. The routes usually run from point to point via radio beacons (sometimes called VORs or NDBs) and points called intersections or fixes. The radio beacons are actual radio transmitters dotted around the globe. Intersections and fixes are imaginary points on the globe which are marked on charts but do not exist as any physical item on the ground. The fixes and intersection points are usually marked at the intersection of two radials from a radio beacon or set at a certain distance from a known point. The airways, fixes and intersections are given names such as a fix name like 'LIFFY' or a route name like 'L975' (which can include multiple fixes) or a VOR name such as 'STRUMBLE' so that pilots and controllers can mention them by name. Pilots flying in the same area over time get to know the names well. 

SIDs (Standard Instrument Departures)
As mentioned above, an IFR aircraft will be following a set path from airport to airport. A SID is a smaller initial route which leads an aircraft from the runway they've just taken off from to the first point in his/her intended route. An airport usually has a lot of aircraft departing from it's runways. To save confusion (and for safety), a busy airport will publish standard routes from it's runways to the various routes away from that airport. This way a controller can be sure that even if a steady stream of aircraft is leaving the airport they will all be following in a nice neat line, one behind the other (that's the idea anyhow!). There is a point called LIFFY to the East of Dublin airport for instance which departing aircraft travelling eastwards (perhaps to an airport in the Britain for instance) will usually fly to as the first point on their journey. Dublin airport has a set route to this point from each runway. These routes are again given names so that controllers and pilots can communicate these procedures to each other. For Dublin airport the standard routes from runway 28 to the LIFFY intersection are called LIFFY2A, LIFFY2B. They are both different paths to the same point, 'LIFFY'. Depending on which runway the the aircraft takes off from, a different standard route will be used. Along with the diagrammatical chart for the departure published by the airport, there is usually a written explanation of how to fly the procedure. This written explanation tells you how high to climb, when to make any turns needed and what VORs to fly towards or away from. 

comment by Bevington: Maybe we can add a drawing of one of the SIDs mentioned above and illustrate how the departing aircraft would actually navigate from the runway to the LIFFY intersection to join the filed flightplan. Another thought would be to add a section discussing that SIDs may be included in the flightplan or could (often) be assigned when the departure clearance is obtained from VATSIM ATC. (same for the STAR section)

STARs (STandard Arrival Routes)
You should be getting the idea now that standard routes are the preferred method to fly from airport to airport. Arriving at an airport is just the same. The standard arrival routes are also published in chart form and allow you to fly into an airport using standard procedures. This way, less communication is again needed with the controllers as (once you have declared your intention or been given a route to fly by name) the controller and you both know exactly how you are going to approach the airport. The end of the STAR route will normally leave your aircraft at a position where controllers can give you final instructions to set you up for a landing. If there are no controllers online you can fly the last part of the procedure using approach charts. If the airport is busy and controllers are over-taxed with work, they might ask you to hold at a point published in your STAR.

It all sounds pretty complicated, and it is at first! But there is great fun, excitement and enjoyment to be had by using these routes and your online flying experience will be greatly enhanced by using them. Online controllers are very willing (if things are not too busy) to give help to newbies practicing these procedures. If you are just starting to use SIDS and STARS put into your comments section on your flight plan something like 'Newbie - practicing SIDs and STARS, please speak instructions slowly (if time permits)'. This lets controllers know that you're not an expert and they will be particularly watching out for you as you fly.

FLYING THE SIDs AND STARs
It is possible to manually fly the SID and STAR routes. Often, on equipped aircraft, a pilot will use a FMC (Flight Management Computer - VasFMC is a freeware FMC) coupled to the autopilot to do most of the flying. You will be busy enough during takeoff and landing without having the extra work of flying the procedures by hand! Remember that in most real world scenarios a pilot will have a First Officer to help with the workload. 

WHICH SID AND STAR SHOULD I USE?
In the normal course of events a SID will be given to you when you have copied your clearance with Clearance or Ground or whichever controller is online. Because each runway has different Standard Departures, the contoller who gives you clearance will most likely tell you which SID you are to fly. After you copy your clearance you have the luxury of a little time before requesting startup or taxi to program that SID into your Flight Computer and program in your initial altitude, heading and speed into your autopilot. Take that time to look at the correct SID and familiarise yourself with what the procedure will be. Mistakes happen - your autopilot might fail or you may have forgotten to program it, so be prepared to fly manually if all else fails. Also remember that the controller can decide not to use a SID at all. The controller may just as easily say to you 'fly runway heading' and then after a minute vector you directy to the first fix on your flightplan! So, always be ready to use the 'direct to' feature in your flight computer.

Below is a typical chart representing a SID from the Dublin Airport (EIDW). It shows the SID from runway 28 to the initial fix LIFFY. It should be obvious that taking off from runway 28, you will be travelling west but that your initial fix is to the East therefore we basically need to turn through almost 180 degrees to get to LIFFY. The SID shows how the controllers would like you to to make that turn and departure towards LIFFY. The chart consists of a diagram of the procedure and a text explanation of how to make the procedure. In reality your SID chart will be more complicated, showing other SIDs on the same chart as well as legal altitudes and speed restrictions. This diagram has been simplified to make it easier to read. Under no circumstances must the accompanying chart be used for real flight purposes.

You can file your flight plan with the SID included. Because there can be different SIDs even for the same runway to the same initial fix (LIFFY in our case), you would normally just file the main SID name such as LIFFY (without the 1B designator). Leave it up to the controller to decide exactly which SID to use. A flightplan from Dublin airport in Ireland (EIDW) to Birmingham airport in England (EGBB) might look like this:

EIDW.LIFFY WAL WHI3A.EGGB

Notice a couple of things.
- The period between EIDW and LIFFY denotes to the controller that you wish to use the LIFFY SID
- Another period between WHI3A and EGBB denotes that you wish to use the WHI3A (Whitegate three alpha) STAR for arrival at EGBB

Which brings us nicely to:

WHICH STAR SHOULD I USE?
The STAR approaches are a little simpler to work with. They may be as difficult to fly initially, but at least you sometimes get to make the choice of STAR in advance unlike SIDs because STARS do not always depend on landing at a particular runway but are decided upon depending on where you are coming from. Just like the SID, a chart is available for each airport which uses them. A STAR will normally get you to a last fix point somewhere near the airport. The STAR does not direct you straight to a runway and so is not tied to any particular runway. It basically ensures that incoming flights who have the STAR published in their flightplan will be expected by the local controller to follow that route and in the case where an aiport is not entirely manned, it gives the controller less work to do to vector the aircraft and set it up for a landing. In the case of no control being available, the STAR also puts you at the right altitude and vector to fly the last part of the approach yourself.

Also published on STAR charts are hold points which are bascially fixes or navaids such as VORs around which the aircraft must circle in a set pattern so that when an airport is busy flights can be 'stacked' at different altitudes by the controller and taken off the hold for final vectors to the airport as needed. The chart example below shows a partial diagram for the EGBB WHI3A STAR. The chart in the example is the procedure for all air traffic arriving from the West of the airport along our route which is called L95 since the fixes we are flying along make up this airway. Under no circumstances must the accompanying chart be used for real flight purposes.

USING A FLIGHT MANAGEMENT COMPUTER OR GPS TO FLY A SID
Content pending


SUGGESTIONS FOR THE BEGINNER
Make sure you understand how to fly to and from a VOR using the instruments in your aircraft and that you fully understand how to file and fly standard routes. If you don't know or are unsure, go through the navigation lessons in MS Flight Simulator (if that's the sim you use) 

FOR PRACTICE
Try to understand and manually fly some SIDs and STARs

Download the charts for two smaller, regional airports. They will look a bit intimidating at first but they will eventually make sense (hopefully with the help of the above information). Print them out and bind and label them such as 'Dublin Airport Information' etc.

You don't have to be online to practice the SIDs and STARs, so practice offline first using the charts before you try it for real. It's a different story when you are online and the pressure of live air traffic control is added to the mix. The controllers as I have said are very helpful, but have some respect for them and don't go online completely without a clue. 

Unless you are very proficient at flying jets, get to know an aircraft such as the Mooney Bravo which is available as a standard aircraft in FS2004 and FSX. It's similar to the Cessna but can travel a lot faster whilst not being as fast as a jet and will give you more time to react to turns and climbs etc. when you are flying the procedures. 

Make sure you have the charts with you 'on board'. Also important are the airport diagrams so you don't get lost getting to the runway once you've gotten your taxi clearance! 

SID/STAR FAQ

Do I need to use a SID if there is no control available?
You should always use a SID where they are available. A controller may log on seconds after you take off and if they see the SID as part of your flight plan they will know exactly what your intentions are. Also make mention of them on UNICOM (122.80) so the local traffic will know what you are up to.

What happens if there is no control available as I'm flying my STAR?
Keep flying your STAR until the last point keeping to the published altitudes and keep an eye out for other traffic. Then consult approach charts for the last part of your flight

References:
VATSIM Chart Center