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Olmo

Circling after an ILS approach

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Hi all,I'm always getting the DUAL LAND annunciation when passing 1500ft AGL while perfoming an ILS followed by a circling with the following cockpit setup:1. Both BARO minimums on the circling MDA (890ft)2. FMA --> LOC - LAND ARMED - HOLD 2100 once established on the LOC3. FCP = MDA (890ft)4. GS capture (FMA --> LOC - LAND ARMED - G/S 2100)I never get the supposed APPR ONLY on the FMA passing 1500ft AGL nor the FMA turns to altitude/heading hold at the MDA. Any advice would be greatly appreciatedRegards,Olmo Matteo DI CARLO

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You only get APPR ONLY when autoland is not available. Either when you disconnect the autopilot and the FMA is providing LOC and GS guidance, or if you are tracking the LOC and the GS is not available with the autopilot engaged, or if theres a failure that would prevent an autoland.


Bryan Richards

 

"People depend so much on automation that they forget how to get the automation to work." B.W.

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Bryan,thanks for the quick reply but APPR ONLY should also be available when performing an ILS followed by a circling as stated on FCOM page PT.30.29 Circling Approach (All Engines)....Regards,Olmo Matteo DI CARLO

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Interesting... one learns something new every day about this aircraft...One to try at home no doubt...Andrew


Andrew Entwistle

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Bryan,thanks for the quick reply but APPR ONLY should also be available when performing an ILS followed by a circling as stated on FCOM page PT.30.29 Circling Approach (All Engines)....Regards,Olmo Matteo DI CARLO
Olmo,What's in the manual there, works in the real aircraft. Doing this procedure correctly in the simulation, does not prevent the Single/Dual Land mode to engage.A real pitty.Next best way to do it:Do not arm the full ILS, but instead arm the LOC ONLY mode and follow the GS indication by using FPA.That way the a/c will at least maintain the selected MDA, and you will be able to select a TRK or HDG mode at a convenient time to start the circling part.Regards,Harry

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A screen shot would help understand what you are trying to do, but I suspect you are in NAV/PROF and when you press APPRLAND you are telling the aircraft to follow the glideslope all the way to touch-down - confirmed with the DUAL indication. When settled on approach, try switching to HDG select (before the DUAL is indicated). Then the aircraft is no longer in autoland mode and should not go below your stated mins. That said, I have never tried this myself.


Paul Smith.

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A screen shot would help understand what you are trying to do, but I suspect you are in NAV/PROF and when you press APPRLAND you are telling the aircraft to follow the glideslope all the way to touch-down - confirmed with the DUAL indication.
Paul,As you state above will happen, UNLESS you select the (baro set) MDA altitude in the FCP altitude window, BEFORE the Single/Dual land mode becomes active below 1500 ft AGL.This according FCOM PT 30.29.This is how it works on the real plane.The simulation lets you select an FCP altitude same as the set Baro MDA (eg 840), but nevertheless goes into Single/Dual Land mode.Sorry, no picture. FCOM text is clear on this subject. Regards,Harry

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interesting, thanks for sharing that bit. It is a real pitty that isn't simulated.


Bryan Richards

 

"People depend so much on automation that they forget how to get the automation to work." B.W.

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Paul,As you state above will happen, UNLESS you select the (baro set) MDA altitude in the FCP altitude window, BEFORE the Single/Dual land mode becomes active below 1500 ft AGL.This according FCOM PT 30.29.This is how it works on the real plane.The simulation lets you select an FCP altitude same as the set Baro MDA (eg 840), but nevertheless goes into Single/Dual Land mode.Sorry, no picture. FCOM text is clear on this subject. Regards,Harry
Hi Harry, I don't find the FCOM to be very clear on this topic at all. How do you interpret the text;
1. Fly the appropriate approach procedure to the MDA with gear down and FLAPS 35 and Vmin +5. AUTO FLIGHT may be used as desired with heading select to maneuver...
There is a slightly better write up on SP.30.5 and SP.30.6 but I think the problem may lay in your last step. From SP.30.6: "When established on the ILS and prior to DUAL/SINGLE annunciation, preselect the FCP altidude to the same as the MDA value". I read this to mean that after capturing the Glideslope, but while still above 1500 RA, you must change the FCP altitude to the MDA value. But this is problematic because the MDA is set to BARO not RA. You might be doing this correctly, and there may be a real fault with the sim, but it is not one of the steps that Olmo listed.
1. Both BARO minimums on the circling MDA (890ft)2. FMA --> LOC - LAND ARMED - HOLD 2100 once established on the LOC3. FCP = MDA (890ft)3. GS capture (FMA --> LOC - LAND ARMED - G/S 2100)4. FCP = MDA (890ft) while still above 1500RA

Paul Smith.

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From SP.30.6: "When established on the ILS and prior to DUAL/SINGLE annunciation, preselect the FCP altidude to the same as the MDA value". I read this to mean that after capturing the Glideslope [..]
Paul, I don't know which version of the FCOM you are using but the one provided by PMDG (04AUG2008) at page SP.30.6 reports exactly the same sentence of page PT.30.29 "When established on the ILS localizer and prior to DUAL/SINGLE LAND annunciation, preselect the FCP altitude to the same as the MDA value."
The meaning of the sentence is the following.....in order to get the APPR ONLY you have to setup the FCP to the preselected BARO MDA after having captured the localizer (FMA --> LOC) but before passing 1500ft AGL. The glide should be captured before 1500ft AGL regardless of the FCP setting. Passing 1500ft AGL + 10 seconds "[..] on LOC and G/S, [..] AFS performs a logic and system status check [..]".The logic would be more or less like this --> on LOC, on G/S, FCP=MDA --> APPR ONLY & altitude/heading hold at MDA.Regards,Olmo Matteo DI CARLO

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Hi Harry, I don't find the FCOM to be very clear on this topic at all. How do you interpret the text; There is a slightly better write up on SP.30.5 and SP.30.6 but I think the problem may lay in your last step. From SP.30.6: "When established on the ILS and prior to DUAL/SINGLE annunciation, preselect the FCP altidude to the same as the MDA value". I read this to mean that after capturing the Glideslope, but while still above 1500 RA, you must change the FCP altitude to the MDA value. But this is problematic because the MDA is set to BARO not RA. You might be doing this correctly, and there may be a real fault with the sim, but it is not one of the steps that Olmo listed.
Paul,===1. Fly the appropriate approach procedure to the MDA with gear down and FLAPS 35 and Vmin +5. AUTO FLIGHT may be used as desired with heading select to maneuver... ===The appropriate approach procedure is your choice, ILS, LOC ONLY, VOR, NDB etc, but the configuration is FLAPS35 max until on final for the landing runway after the circling.Autoflight may be used during approach to the MDA and during the circling procedure at MDA. The text 'with heading select to maneuver... ' is not meant for the approach to MDA if better options are avail, but for the circling after that.For obvious reasons I use TRK for that.==== I read this to mean that after capturing the Glideslope, but while still above 1500 RA, you must change the FCP altitude to the MDA value. But this is problematic because the MDA is set to BARO not RA.====Don't see the problem here, did you try this?Set a BARO MDA as your circling limit, then on the approach select the FCP Altitude down to that limit. It will snap-on to the set MDA value. Say your circling MDA 960 ft. When selecting the FCP altitude towards this value it will decrease by steps of 100 initially but snap-on to 960 this way. ---> 1200, 1100, 1000, 960, 900, 800.Hope this clears your questions.@ Olmo:Your procedure and understanding is correct. Pitty the simulation is missing this feature.Regards,Harry

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Hi Harry, Olmo1st an apology, I was quite wrong about the glideslope requirement, sorry for any percieved impugnment. After slightly more TOGA's then beers, I think I can safely say that the manual leaves room for improvement, mind you, so do my flying skills :( . I can at least catagoricaly state that the "note" which has been quoted so often on this thread does not reflect the implementation - it is wrong. In particular, if the PF has pressed APPR/LAND and the aircraft is tracking a valid ILS beam, then unless the pilot makes a decision to do something else BEFORE MDA is reached, then the AP will attempt to land the plane in Dual mode if possible. (This seems very sensible to me but does not match the documentation - can someone who knows the real-world procedures please comment on this?) What I successfully did on my attempts to land ILS circling was; Set FCP alt to xxx so that I would intercept GS from belowWhen flying straight and level towards expected intercept, select APPRLANDLAND ARMED shown in whiteWhen PNF calls out "Localiser Alive" NAV changes to LOC (in white) Alt shows LAND ARMED in white above Hold xxxChange FCP alt to MDA (As Harry pointed out, the FCP altitude will 'snap' to the MDA)When GS is captured, the AP starts descentIF - I do nothing, at MDA the AP takes over and switches to DUAL LANDelse IF - I select HDG or TRK, AP levels out at MDA and lets me decide what to do nextThis image is from just before I started my turn


Paul Smith.

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1st an apology [..]
Why? We are all here to share the same passion, trying to have fun and why not...maybe also learn something.
[..] I think I can safely say that the manual leaves room for improvement [..]
Right but I can assure you that PMDG's AOM is a faithful copy of the original one.
[..] if the PF has pressed APPR/LAND and the aircraft is tracking a valid ILS beam, then unless the pilot makes a decision to do something else BEFORE MDA is reached, then the AP will attempt to land the plane in Dual mode if possible.
Right, the a/c will always try to provide a DUAL LAND irrespectively of the ILS category you are going to fly (except during circling) as long as AP and ATS are engaged.DUAL LAND doesn't mean that your are commited to a full autoland but that all system involved are fully functional and comply with the Fail Operational criteria:"[..] in the event of a failure below alert height, the approach, flare and landing, can be completed automatically. In the event of a failure, the automatic landing system will operate as a fail-passive system" (EU-OPS).In these way you are allowed to shoot an ILS CAT III where a "[..] fully coupled automatic approach and landing, through touchdown and ground rollout [..]" is required. "SINGLE LAND provides same performances as DUAL LAND but requires higher minimums due to its fail passive capability". EU-OPS tells us the meaning of fail passive:"A flight control system is fail-passive if, in the event of a failure, there is no significant out-of-trim condition or deviation of flight path or attitude but the landing is not completed automatically. For a fail-passive automatic flight control system the pilot assumes control of the aeroplane after a failure."I'm not an expert about american pubs but those 2 files are suggested for the ones that want to have even more reference...AC120-28D CRITERIA FOR APPROVAL OF CATEGORY III WEATHER MINIMA FOR TAKEOFF, LANDING, AND ROLLOUTAC120-29A CRITERIA FOR APPROVAL OF CATEGORY I AND CATEGORY II WEATHER MINIMA FOR APPROACH
IF I do nothing, at MDA the AP takes over and switches to DUAL LAND
From that point on you could still use the EXIT FROM APPROACH MODES procedure (SP.30.6) by pressing the G/A button followed immediately by an altitude/heading mode or the SIDE STEP MANEUVER FROM ILS APPROACHES (SP.30.7) by disengaging the AP and tuning a fake ILS frequency --> "[..] system will immediately drop to basic modes [..]".Regards,Olmo Matteo DI CARLO

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