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"EXPECT" STAR altitudes appear in FMC by default


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The AIM says this about STAR altitude constraints that are designated by the phrase "EXPECT".

 

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 “Expect” altitudes/speeds are not considered STAR procedures crossing restrictions unless verbally issued by ATC.....The “expect” altitudes/speeds are published so that pilots may have the information for planning purposes. These altitudes/speeds must not be used in the event of lost communications unless ATC has specifically advised the pilot to expect these altitudes/speeds as part of a further clearance.

 

It is my understanding that ATC (r/w--I have no idea how the MSFS ATC would try to handle this) actually issues serial clearances for crossing altitudes during descent on STAR procedures that include "EXPECT" crosssings. For example, on the SWL transition to the JIIMS3 STAR at KPHL, the controller would actually issue the clearance, "Cross RADDS at and maintain 15000", which would be followed at the appropriate points in the arrival for crossing altitudes at HEKMN and JIIMS.

 

So my question is the following: Is it correct for the FMC to fill the altitudes for those three expected crossings, or should they remain blank by default? Of course, in single pilot flight sim operations, we can do as we please, so pilots could enter the expected altitudes in advance, just to make life easier while we juggle the throttles, etc., but I'm asking this in principle. My recollection is that in other study level aircraft I have flown, these expected altitudes are not prefilled when the STAR is first selected.

 

I could imagine that one or the other of these two possibilities could be wrong or they both could be correct, i.e., Boeing and Airbus do it one way, but Mitsubishi does it another.

 

Many thanks in advance to anyone who has r/w experience with these devices. We are very much indebted to pilots who are kind enough to share their knowledge and enthusiasm for our hobby.

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  • Deputy Sheriffs

It's normal for the altitudes to be populated. If you get different instructions, you just change them.  Many times the clearance would be "Descend via the JIIMS3 arrival" and they'd give you short cuts traffic permitting.

 

Best wishes.

 

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For folks reading this who may not know about the various CLIMB VIA / DESCEND VIA instructions, the FAA has a nice FAQ:

https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/afx/afs/afs400/afs410/pbn/media/Climb_Descend_Via_FAQ.pdf

 

I suspect the argument is that you are more likely to get assigned the EXPECT restriction in busy airspace (it is in the SID/STAR to help make traffic flow more consistent and predictable), then it makes sense to pre-populate (you're more likely to use it than not).  That decision may be up to the manufacturer of the aircraft, FMS, operator, etc. though...

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59 minutes ago, CaptJohn said:

So my question is the following: Is it correct for the FMC to fill the altitudes for those three expected crossings

 

Yep. It's correct.

 

1 hour ago, CaptJohn said:

I could imagine that one or the other of these two possibilities could be wrong or they both could be correct, i.e., Boeing and Airbus do it one way, but Mitsubishi does it another.

 

 

Boeing, Airbus, Mitsubishi, Bombardier, Dassault, Embraer all do it this way and I'm glad they do. I can count on one hand the amount of times I've been given something other than the expected altitudes. Not to mentioned most STARs have 5-10 waypoints. It would be annoying as hell having to manually put the altitudes at each waypoint (if they each have a constraint of course).

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First, thanks everyone for your responses. I was able to check the performance of the Toliss A319 in X-Plane, and its MCDU did not fill in the "expected" altitudes for the JIIMS3. I'll check on the Zibo Mod B738 once I figure out how to get the latest version downloaded and running. Of course, these are only add-on modules and may not reflect real world performance. It is important to note that the CRJ FMS clearly labels those crossing restrictions with the word "EXPECT", so pilots know that these do not represent mandated crossing altitudes unless so cleared by ATC and that the entries are there for convenience only. So that settles my original misgivings about how this was displayed.

 

This whole Climb via/Descend via business represents numerous opportunities for confusion between ATC and pilots. The FAA 7110.65 ATC publication states in para 4-5-7 that "A “descend via” clearance must not be used where procedures contain only published “expect” altitude and/or speed restrictions", so pilots wouldn't ordinarily receive a "Descend via the JIIMS3 arrival" clearance. In contrast, the KORRY4 arrival to KLGA displays hard altitude restrictions (with no EXPECT qualifiers), and here ATC does normally issue a Descend Via clearance. This is noted in the introductory notes at the top of the instrument procedure plates. And indeed, it would be very annoying to have to fill in all those altitudes by hand.

 

Thanks again for a very helpful discussion.

 

 

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@CaptJohn

 

Just for clarity and for this thing to not go anywhere it does not need too which happens pretty quick on this forum sometimes.

@Chaxterium

Is making reference to Real Planes and Real clearances in Real Airliners.... His reference to operation of the FMC/CDUs are to Real planes and not to a Toliss implementation.

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Les, I agree completely and hope I made that clear.

 

5 hours ago, CaptJohn said:

Of course, these are only add-on modules and may not reflect real world performance.

 

Cheers.

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Just now, CaptJohn said:

Les, I agree completely and hope I made that clear.

 

 

Cheers.

 

And I should add that my reference to the ATC clearances is only meant to apply to FAA-land. This may work differently in other areas.

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  • 4 weeks later...
  • CRJ Forum Moderator

I was surprised to read the comments saying expect altitudes were in the FMS. In fact, if you google FAA JO 7100.9E, which was the FAA's guidance for developing STAR's, it specifically says “Expect altitudes or airspeeds are not coded into an aircraft navigation database". I have flown the Collins FMS's for a long time on a variety of airplanes, and never once has it loaded an expect altitude for me. But, 100% of the aircraft I have flown have had a Jeppesen nav database. If you have a Lufthansa database (like Aerosoft uses), it turns out there is a note that says “Expected Altitude constraints published in SIDs and STARs are often included in the LSY database". So I think the correct answer is, it depends on the class of nav database that you have loaded. Learned something new! 

 

 

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That's very interesting. I should have noted that I am using the Navigraph subscription data, which I believe is derived from Jeppesen. But as noted above several times above, I'm just working off of various flight sim models, not the real thing.

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