During the planning stage of an IFR flight how to choose the correct SID for your route in an airport with multiple runways and multiple SIDs? and how to predict the runway you will be going to use?
3 Answers
"File what you want, fly what you get."
There's no way to know for sure what clearance ATC will give you until you actually call them. If you're departing from an airport that you know well then you may be able to make an educated guess but that won't help if the winds change, an incident closes a runway, or any number of other things happen to invalidate your assumptions.
For planning purposes, just use the SID that best fits your needs, based on all the information you have available: direction of departure, aircraft type, weather, local procedures etc. But ultimately, you'll have to fly what you get (or what you can negotiate with ATC).
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1$\begingroup$ Picking one which gets the departure fix that you would like is about the best you can do... $\endgroup$ Commented Mar 30, 2018 at 20:07
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$\begingroup$ Which runway do you plan if the airport has many of them and you are not familiar with it? $\endgroup$ Commented Mar 31, 2018 at 7:13
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$\begingroup$ @AndreaGhilardi, usually the SID chart has a route from each runway to a common waypoint. So you chose your preferred departure waypoint and leave it up to the tower to tell you which runway is active for departures. $\endgroup$ Commented Jan 9, 2020 at 20:24
The runway(s) in use will depend primarily on the winds at the time, though there are other factors such as maximum arrival/departure rate that may take precedence, especially if the winds aren't very strong. It's disruptive to traffic flow to change the active runway, so when the winds change, they will often wait until there's a natural lull in the traffic or a pilot rejects the assigned runway(s) because the crosswind or tailwind component exceeds their limitations (which varies by aircraft and pilot skill).
You can also request to use a specific runway. For instance, pilots may accept a crosswind or even a tailwind to get a runway with the shortest taxi time to/from parking, or allows a straight in arrival or straight-out departure, or is longer than the one aligned with the winds to provide more safety margin, etc. Whether ATC grants such a request will depend primarily on the manageability of potential conflicts with everyone else following the normal plan, which mostly boils down to how much traffic they're juggling at the moment.
Regarding the SID, usually there's either one generic SID for all departures, or there's a set of SIDs (or one set using VORs and another using RNAV) divided up by direction so only one of them would makes sense for your flight.
That can be selected based on whether the SID is intended for use by your type of aircraft, as well as your aircraft’s performance capabilities and onboard avionics (eg an RNAV SID is useless unless your plane has RNAV equipment aboard or can’t meet the minimum required climb rates, etc.). As stated above, depending on your aircraft type and airport, ATC may or may not clear you to fly that SID. EFB apps like ForeFlight do have the capability to show previously cleared routes so you can get a sense of how ATC likes to handle airplanes for those routes. Also be aware of IFR Preferred Routes or TEC routes on the east and west coasts which will be often used by ATC and will influence what DPs you choose.