Monitoring raw data A320
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Monitoring raw data A320
The new FCOM has a reference regarding the use of NAV mode.
So long as GPS primary high
OR
Nav accuracy high
OR
Reference raw data
So is Airbus really saying that as long as accuracy high then you can blindly follow the flight directors without monitoring with raw data at all.
Are you legally required to back up with raw data?
I take that reference to mean that even if the beacon required is U/S then you can fly the SID anyway as long as you have GPS Primary.
So long as GPS primary high
OR
Nav accuracy high
OR
Reference raw data
So is Airbus really saying that as long as accuracy high then you can blindly follow the flight directors without monitoring with raw data at all.
Are you legally required to back up with raw data?
I take that reference to mean that even if the beacon required is U/S then you can fly the SID anyway as long as you have GPS Primary.
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According to Limitations published you can fly an NDB OR VOR approach with the ground facility unserviceable or airborne equipment unserviceable/ not installed ( with GPS PRIMARY ) providing you have regulatory approval. So yes the NAV system is capable of navigating without the raw data available.
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...and therein lies the problem. At least in EASA territory that approach would need to be approved and published as an RNAV overlay. I'm surprised Airbus writes anything about this in the limitations chapter, this is absolutely not their call to make - BMW don't write in their driver's manual that use of the indicators is optional (providing regulatory approval)
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Ah well, not so different from Boeing that wrote in their 737 FCOM (dunno if its still in there, but it was for several years) that GPS is actually not required for a GPS approach as long as NAV accuracy is high enough.
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you are referencing the limitation for NAV mode in terminal area. further down the chapter FCOM is pretty clear on approaches based on radio navaids. and how would you monitor RNAV only SIDs/STARs by means of navaids when they are not referenced to a navaid?
keep in mind certain equipment has to be functional for certain RNAV ops as well
keep in mind certain equipment has to be functional for certain RNAV ops as well
Playing devil's advocate, isn't the RNP the same for either approach?
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applecrumble
No! Definitely not. Requirements of using NAV mode differ depending upon where you plan to use it. On route, in terminal area, in managed approach with a NAV aid or GPS approach. Quoted from FCOM:
In GPS approach there cannot be a back up. In managed VOR approach you need to back it up with VOR although with regulatory approval the approach is permitted without the NAV aid because GPS accuracy is better than the NAV aid itself.
So is Airbus really saying that as long as accuracy high then you can blindly follow the flight directors without monitoring with raw data at all.
For RNAV(GNSS) approach: GPS PRIMARY..................................................... ...........................................................C HECK ‐ GPS PRIMARY must be available on at least 1 FMS.
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Thank you for your replies. I really meant regarding a SID.
Airbus allows you to free tune the nav aids so you might not have what you need to monitor the SID anyway.
Airbus allows you to free tune the nav aids so you might not have what you need to monitor the SID anyway.
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CDI indication
While on this subject; so, with my previous operator we had the following:
Any GNSS, RNP or -AR, passing the FAF, the CDI under the PFD was visible and actually requiered.
I actually did not make of it much until a small discussions on FB about CFI’s teaching GNSS approaches, but my current operator the CDI does not appear during those approaches.
Logic dictates that “full scale CDI deviation” merits a Go-Around (if RNP is 0.3 and you have full scale on CDI you are 0.3NM or more off course/Centerline) but in our SOP’s it shows that the PM is to “monitor closely the lateral deviation” and nothing else...
Under the circumstances at my new operator it would NOT surprise me if they just too ignorant or simply don’t want to pay Airbus for the approval and made this **** up... any thoughts?
Any GNSS, RNP or -AR, passing the FAF, the CDI under the PFD was visible and actually requiered.
I actually did not make of it much until a small discussions on FB about CFI’s teaching GNSS approaches, but my current operator the CDI does not appear during those approaches.
Logic dictates that “full scale CDI deviation” merits a Go-Around (if RNP is 0.3 and you have full scale on CDI you are 0.3NM or more off course/Centerline) but in our SOP’s it shows that the PM is to “monitor closely the lateral deviation” and nothing else...
Under the circumstances at my new operator it would NOT surprise me if they just too ignorant or simply don’t want to pay Airbus for the approval and made this **** up... any thoughts?
Last edited by EagleA25; 5th Jan 2018 at 08:28. Reason: Spelling and grammar
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According to Limitations published you can fly an NDB OR VOR approach with the ground facility unserviceable or airborne equipment unserviceable/ not installed ( with GPS PRIMARY ) providing you have regulatory approval. So yes the NAV system is capable of navigating without the raw data available.
EagleA25
In our Airbii there is no CDI at all in NAV, so we are only allowed NAV with AP and/or FD. there is a numerical cross track deviation, giving miles left/right off course, on the Nav display. I have always been amazed that Airbus certified it this way, as there is a requirement in most AIPs I have seen for a CDI which changes sensitivity based on phase of flight (enroute 10 miles down to approach 0.3 miles for full scale). I really don’t like not having a CDI, and with EFIS it would be (relatively) easy to implement.....
In our Airbii there is no CDI at all in NAV, so we are only allowed NAV with AP and/or FD. there is a numerical cross track deviation, giving miles left/right off course, on the Nav display. I have always been amazed that Airbus certified it this way, as there is a requirement in most AIPs I have seen for a CDI which changes sensitivity based on phase of flight (enroute 10 miles down to approach 0.3 miles for full scale). I really don’t like not having a CDI, and with EFIS it would be (relatively) easy to implement.....
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Hey hans
Thanks for your post; We do the same at my operator and I am not sure if the manufacturer actually approved this way of “doing business”.
Reading a few comments after your post actually now makes me feel nervous...
As some mentioned, I would feel a lot safer with an established LDEV attached to the VDEV, or is the Yo-Yo sufficient?
Thanks for your post; We do the same at my operator and I am not sure if the manufacturer actually approved this way of “doing business”.
Reading a few comments after your post actually now makes me feel nervous...
As some mentioned, I would feel a lot safer with an established LDEV attached to the VDEV, or is the Yo-Yo sufficient?
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Can only speak for the 737. On the classic there was actually a NAVigation mode for the ND which displayed a normal CDI display with additional turning cues for both enroute LNAV operation as well as departure and approach indication. On the NG we had navigation performance scales, which displayed the ANP corridor as well as the LNAV path (same for VNAV during descent) in the PFD. For approach we used IAN which shows the same ILS symbology (including ghost pointers when still on LNAV to the approach) as a normal ILS. That symbology is completely independent of the FD or autoflight system and allowed flying without FD during RNAV or overlay approaches. GLS simply used the same ILS symbology again, but was autoland and auto-rollout capable, but not approved for that.
See also Aero 22 - 737 Approach Navigation Options
See also Aero 22 - 737 Approach Navigation Options