IFR departures...question

[CHERN]

This may or may not actually make any sense, but I'll try to explain my question the best i can...

I just recently have begun looking at IFR departures in the hopes that I can make my IFR flights in FS a little more realistic. I understand the departures themselves (though I may not be looking at them correctly, no one ever actually told me how to read departure plates, I kinda looked at it and did my best to understand). But it appears that at some airports, a lot of the departures are essentially interchangeable...

A good example is CICERO TWO departure and MIDWAY FOUR departure for Midway airport in Chicago (KMDW).

CICERO TWO: http://myairplane.com/databases/appr...0081CICERO.PDF

MIDWAY FOUR: http://myairplane.com/databases/appr...0081MIDWAY.PDF

How does a pilot know which one to use? Both departures have a procedure for Runway 4R for example. It would appear that the only difference between these two is when you make the initial turn to heading 100 (midway four within 4 DME and Cicero two at 1.2 DME from KMDW itself).

I guess if your airplane does not have DME, then you have to use MIDWAY FOUR, but pilots with DME have a choice? I'm pretty sure I'm missing something here...

Thanks for the help!

:-wave

[RONONYMOUS]

Well, I'll try my best to explain this.

Generally speaking when you file an IFR flight plan you do not include DP's in your route. As a matter of fact some people like to put "no dp's" in the remarks section of their flight plan log (this does not stop controllers from assigning you one if they need to). While at some airports there are some preferred DP's that are used ie. at Westchester County, the Westchester One departure is very common for all aircraft, it is rather rare at most airports especially for light aircraft to be assigned a DP. There are a few factors that play into whether you're assigned a DP or not, the main one being what the controller's workload is at the time. More often than not they will just assign an initial altitude and heading and then clear you to your first waypoint on the assigned flight plan.
Also, just so you know, when you file an IFR flight plan unless you're using a "preferred route" or "TEC route" as listed in the back of the AFD you will probably get a different route than what you filed.
In short, you will seldom be the one to determine what your DP will be if any at all, that will be determined when you receive your clearance right before departure. That's one thing about IFR flying that takes a little getting used to, but no matter what route you planned you have to remain flexible to the "here and now" as you will almost never fly the exact flight you originally planned.

I hope this somewhat helps. Jeff, Larry??? Feel free to chip in here.

[OStateFlyer]

I have to respectfully disagree with some of the items in the above post. If I'm flying the airways and not /G Direct, I use DPs if they suit my routing...they are a nice safe shortcut for me and ATC. They make things easier for everyone involved...for example, I left McKinney, TX, IFR, in a Baron...we had filed /G Direct Enid, OK. Every previous trip we were cleared as filed, no sweat, no DPs. On one particular trip, there was a snafu in the system which lost our flightplan (it had been filed something like 3 hours before), so we had to pick up a new clearance after filing again with the tower, and then hold for our clearance and an IFR release. Instead of the usual cleared as filed, we get this wonderful convoluted series of turns, X DME from Y, then XYZ Radial, etc, then finally direct. It would have been much easier for us to file a DP out of the DFW area and then direct from a transition. Had we not been sitting in the plane with passengers in the back, we probably would have taken the time to do that. Hindsight is 20/20 eh...DPs work wonders in busy airspace.

As far as being assigned a DP, you can always turn down an ATC clearance if they assign a DP. You may have to go in the penalty box over some fix and hold, or sit on the ground for a while, but you don't have to accept the DP. In my experience, the pilot is the one who decides if he gets DPs when he files one or doesn't file one, the same with routing. Busier parts of the system are a little more strict on routing, but the overwhelming majority of places you get cleared as filed unless you really screw up the routing. If you really screw up the routing, and you file with FSS, they'll probably call you on it when you file. If you aren't the one picking the DPs and STARs you're flying, then something seems wrong. By looking at the procedures, you should be able to tell what will work out to the advantage of ATC and yourself most of the time, and then file it.

For more on STARs/SIDs/DPs...check out http://www.avweb.com/news/system/183200-1.html


Brad

[Jeff S KDTW]

Instrument departure procedures are preplanned instrument flight rule (IFR) procedures which provide obstruction clearance from the terminal area to the appropriate en route structure. Technically speaking, the purpose of a departure procedure is to provide obstacle clearance protection information to pilots and to increase efficiency and reduce communications and departure delays at busier airports. This permits the controller to quickly relay clearances to aircraft without having to name each waypoint and altitude restriction--think of it as shorthand.

To answer the initial question--how to select which DP to use? Well, you have partly answered it. If you don't have the required equipment, that will eliminate some DPs. If your route doesn't include one of the published waypoints on the DP, that may eliminate others. If there are multiple ones remaining, often times there is one that is locally preferred by the controllers. Pick one, file it, and hope you get it. If you get a different one, well, try that one the next time. :-)

A couple additional points:

Filed flight plans can certainly include DP. In fact, if you include the one most likely to be assigned, you increase your chances of getting "cleared as filed" in your initial callup.

Including "No DP's" in the remarks will keep a controller from assigning one, since it is usually used to indicate that the pilot does not have the printed DP onboard. In those cases that the controller needs you to fly it, they will resort back to having to read the procedure to you over the radio during your clearance.

The chances of getting a DP is more dependent on established routes and procedures rather than current workload. Remember, the main purpose of an IFR clearances, including departure procedures, is so that the controller(s) and the pilot(s) have a coordinated plan in the event that communications are lost. The controllers will know where you are flying to, what route and altitudes, and will be able to direct conflicting traffic accordingly.

[flyinggriffin]

What you will notice between the DPs or STAR for that matter is the crossing altitudes and speeds. On the departures you also have to make sure that your plane is up to the task and can climb as fast as the procedure calls. Think about someplace in Colorado, on a hot day at 3 or 4 thousand feet before you factor in density altitude. Can your bird make the required climb before it turns itself into scrap on a hillside.

I would suggest that you hop over to Avweb.com. Look up the columns by Dan Brown a long time controller in the Atlanta area. I believe that the column name is "Say Again?" Loads of information and a lot of tips on how to fly in the real world system.

[CHERN]

thanks guys...that really helped!

So, I guess due to the limitations of FS (in that the ATC system does not support published departures or approaches), I get to choose the one that fits my airplane and route best, but IRL that isn't always the case.

Thanks Again!

:-wave

[KathyPilot]

"How does a pilot know which one to use? "

Although all the above posts are full of great information, the answer to your specific question is actually quite simple.

Whenever you see almost duplicate DPs you need to ask why - which is what you did. In many cases there are different DPs for time of day (noise abatement) or special events, etc.

In this case, Midway, the Midway Four departure is the normal day-time departure. The Cicero Two departure is for night ops - noise abatement - its paths are away from residential areas.


So, if you were departing at night you would recieve or ask for Cicero Two.

Hope this helps.
Kathy

[Jeff S KDTW]

All right, Kathy. How did you glean that conclusion from those plates?

You have me puzzled.

[KathyPilot]

"You have me puzzled"

Well......it's about time..I hardly EVER get to puzzle you. :-lol

The answer choices are:
1. Been there, done that.
2. Slept at a Holiday Inn Express last night.
3. I read a lot (Evelyn Wood is my mentor).
4. All of the above.

Other than the above, there is NO WAY to discern which one to use. This is one of the few I know about that DOES NOT state right on the front "This SID is a Noise Abatement procedure", yada yada.


Thanks Jeff, you gave me a smile today. I owe ya one.

Kathy

[CHERN]

thanks Kathy...I guess part of knowing what do some times comes from actually doing it...

'2. Slept at a Holiday Inn Express last night.' :-lol:-lol:-lol

I love those commercials...

:-wave