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RNAV Departure?


John Smith 1454197
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Hey, so on my last Vatsim flight after I contacted the departure controller while departing on my SID. The departure controller told me for future reference that it was an RNAV departure and the rest of his explanation I couldn't quite understand. However after looking up RNAV departures it turned out an RNAV departure seemed to be a SID departure. This got my confused as I was following the SID I was cleared for in my IFR clearance at the time. I think a possibility is that there was a miscommunication on my part. As I was departing I greeted the departure controller with a standard "Climbing through" "Inbound waypoint" greeting, however after looking at some other Vatsim videos I saw some people said things like "Climbing via SID". Was a miscommunication on my part like that possibly the issue which might have caused the departure controller to not know I was following a SID or is there a part of RNAV departures I may have missed?

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There are conventional SIDs and there are RNAV SIDs. Basically you can follow a conventional SID by means of VOR, DME and NDB. To follow an RNAV SID you need to be able to fly Area Navigation with a certain degree of precision which is defined under PBN (Performance Based Navigation): Skybrary PBN page

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That's interesting! Ok, do the following: search the internet with the terms "skybrary RNP" and you'll get the same address with the correct content.

 

EDIT: I found the error! The forum software somehow truncated the last letter of the URL which happens to be a bracket ")". I have now re-formatted the URL and it works nicely: Skybrary PBN page

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Whether or not a SID is RNAV doesn't really make the key difference. Look at the JCOBY and RNLDI departures out of Dulles (KIAD). Both are RNAV, but, they are different in a very important way. The RNLDI is a Pilot-Navigated SID which means you're responsible for your own navigation as soon as you go wheels-up. The JCOBY is a Hybrid SID, meaning that it starts as vectored then becomes pilot-nav once told by ATC to join the departure. When filing the JCOBY you are responsible for knowing what heading you should fly before being told to "proceed direct RIGNZ", and stay on that heading (and no higher than the "top altitude") until told by the Departure controller.

 

Pop Quiz: departing 19L from KIAD on the JCOBY, what heading should you be on?

Cheers,

-R.

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191 to 820ft, then a 320 hdg till instructed otherwise; climb and maintain 3K (top). All of this of course can be instructed differently by the controller. Expect to be vectored to JCOBY (or any other fix on SID). A couple of things you should be (all things Vatsim of course...) RNP1, a turbo-jet aircraft, and IRW a radar controller.

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Well, there is no general rule for SIDs/RNAV SIDs!

 

In Germany conventional SIDs usually have a paired "RNAV OVERLAY SID", which means your FMS will have waypoints coded as in this OVERLAY, while actually following the same path as the conventional SID. Then they will have the same designator and serial number, e.g. "ANEKI 9L". When you insert this SID from EDDF you will find a list of WPTs that are not show on the conventional SID-chart and you may get confused. Continue searching for the correct chart that will contain those fixes. But as there is no general rule to this, some German airfields may have SIDs that come along with completely different lateral paths, although they have the same identifier, but a different serial number. So watch out what your clearance is, make a clear readback to give ATC a chance to catch possible errors. That's why you should quickly scan through all SID-charts before calling for clerance. This way you will be aware if there's another SID with the same identifier and you won't get surprised by an ATC-clearance differing from your expected SID. Try to be one or two steps ahead of the game, keep your situational awareness up and expect the unexpected. That's how we do it "in the real thing".

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I doubt your radio transmissions were the cause of the confusion. Upon initial contact, the departure controller already knows you're coming, they have your flight plan and clearance, and they've probably already spotted you on the scope. Whether you say "climbing" or "climbing on the SID" doesn't really matter an awful lot; the only reason you mention your altitude clearance at all is to make sure you and the controller are on the same page (i.e., you have the clearance that the controller expects you to).

 

My guess would be that you filed a flight plan with an equipment code that indicates "no RNAV available", but somehow got cleared for an RNAV SID regardless (maybe you filed it, and delivery wasn't paying attention) - if this happened IRL, you would have had to reject the clearance and request a non-RNAV SID. So maybe that's what the departure controller was trying to tell you.

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My guess would be that you filed a flight plan with an equipment code that indicates "no RNAV available",.

 

 

Should probably mention this, I was in a Boeing 737 and had the SID loaded up on my fmc I don't know if the FMC doesn't support sids or not but from the research I did, with RNAV SIDS they are followed by the fmc usually.

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My guess would be that you filed a flight plan with an equipment code that indicates "no RNAV available",.

 

 

Should probably mention this, I was in a Boeing 737 and had the SID loaded up on my fmc I don't know if the FMC doesn't support sids or not but from the research I did, with RNAV SIDS they are followed by the fmc usually.

IF you have the departure runway set correctly, and IF your autopilot in the right mode, and IF you have the initial climb altitude set correctly.

 

Autopilot and FMC are tools to help reduce pilot workload, but pilot is still in charge of complying with the procedure.

Cheers,

-R.

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hmmm, Maybe it was the initial climb altitude because I had the right runway I'm pretty sure. I guess if this happens again I'll follow up with the controller because he's really the only one that was there with me and could probably identify exactly what I did wrong.

 

I will definitely have to pay more attention to this in the future though.

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Upon initial contact, the departure controller already knows you're coming, they have your flight plan and clearance, and they've probably already spotted you on the scope. Whether you say "climbing" or "climbing on the SID" doesn't really matter an awful lot; the only reason you mention your altitude clearance at all is to make sure you and the controller are on the same page (i.e., you have the clearance that the controller expects you to).

 

Not to mention, we are all on the same network servers, so there is no real radar in use. So the "verifying" of the altitude is just part of playing the game, and continuing the immersion. Even if it's off for some reason, it's only electrons on the internet, and no real metal will get bent.

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Real metal or virtual, I believe confirming the altitude *clearance* is more important than confirming the *current* altitude.

 

The ATCO already gets your altitude from your transponder signal; if your reading is wrong, then so is theirs, and if there is a discrepancy between the two, it's still not obvious what exactly went wrong, or how to fix it - all you know at this point is that at least one of those readings is incorrect, which means you have lost situational awareness, which means you are now in an emergency situation. But this isn't a problem specific to handovers; altimeter failures can occur at any moment during your flight, so there isn't really a huge reason to report altitudes specifically on initial contact.

 

What happens more easily, and more specifically during a handover, is that either you copied your last clearance incorrectly (or missed it entirely), or that it got butchered in the handover on the ATC side. Either way, what you think you're cleared for is no longer what ATC thinks you're cleared for, and there is no automation to keep this synchronized - the radar scope only knows what ATC thinks you're cleared for, and you, your copilot and your aircraft only know what you think you're cleared for. Hence, you need to tell ATC what you think you're cleared for, and they check it against what they think you're cleared for, and if the two don't match, there is ample opportunity (and procedure) to rectify the situation.

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Real metal or virtual, I believe confirming the altitude *clearance* is more important than confirming the *current* altitude.

They're both important. In the US, **every** time you're handed from one radar controller to another, you verify your current altitude. That's to ensure your Mode-C is in fact reporting your altitude correctly as reflected in your data block on the controller's scope. That has nothing to do with verifying what you're cleared for. However, verifying that is important too, which is why the second part of that check-in includes verifying the altitude you're climbing or descending to. If you're climbing or descending via a procedure that includes a series of altitude restrictions, "climbing via the _____" or "descending via the _____" confirms to the controller that you're aware of and intend to meet those restrictions.

Cheers,

-R.

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The JCOBY is a Hybrid SID, meaning that it starts as vectored then becomes pilot-nav once told by ATC to join the departure. When filing the JCOBY you are responsible for knowing what heading you should fly before being told to "proceed direct RIGNZ", and stay on that heading (and no higher than the "top altitude") until told by the Departure controller.

 

This is important to note i think. At CYYZ all our SIDs are hybrid SIDs. You are expected to fly a slightly diverging heading (Or runway heading is fine too) until instructed to turn, it's published on the departure charts. I've seen far more pilots than i can count that turn immediately after takeoff then blame their autopilot/fmc. The autopilot and FMC are only doing what they are told to. You deleted the "(vectors)" part in your FMC, either because you didn't know what it was for or didn't care/ didn't bother to look it up.

 

Find the charts and read them. They are easily accessible online, if you don't understand, just ask the controller. It might take us a minute if we're busy but we'll help you out. PLEASE don't just delete a "vectors" line in your FMC and hope for the best, it's there for a reason.

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Ben Stevenson

Chief Instructor

Toronto FIR (CZYZ)

torontofir.ca

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At CYYZ all our SIDs are hybrid SIDs. You are expected to fly a slightly diverging heading (Or runway heading is fine too) until instructed to turn, it's published on the departure charts. I've seen far more pilots than i can count that turn immediately after takeoff then blame their autopilot/fmc. The autopilot and FMC are only doing what they are told to. You deleted the "(vectors)" part in your FMC, either because you didn't know what it was for or didn't care/ didn't bother to look it up..

Right -- or, delete the line, but ensure your aircraft is in HDG mode and dialed into the [Mod - Happy Thoughts]igned heading you were given, and not LNAV mode. If flying a hybrid SID, I'll almost always do that, and then "rejoin" the magenta line when and where I am instructed to by ATC. (That might mean modifying that line, too, if told "direct {XXXXX} from present position.") Doesn't matter as long as you comply with the procedure and the instruction (and, in a multi-person crew setting, as long as all crew members are on the same page as to what will be done).

 

(That's true on VATSIM at least -- I presume there are airlines out there which dictate how that situation must be handled. I just feel as though putting the aircraft in LNAV mode but having it follow a heading is less empirically intuitive than having it in HDG mode if I'm supposed to be flying a certain heading instead of a pre-programmed path.)

Cheers,

-R.

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