RNAV (LNAV- VNAV) Approaches

 

All RNAV approaches must be flown with autopilot and flight director unless no ILS is available and both autopilots have failed, then a manual FD RNAV is permitted. RNAV approaches only use one autopilot. Second autopilot will not engage. Only use approach from database, do not manually build approach. RNAV approaches that are listed as LVAV-VNAV are designed to provide vertical guidance and will utilize a DA(H).

 

When cleared for the RNAV approach press the APPR pb on FCU. Do NOT select the LS pb! LS pb will disable the RNAV indications and flash amber V/DEV on the PFD.

 

Enter 0.3 for required accuracy on PROG page (make sure the new value shows on both sides). This lowers the FMGC “tolerance” from an enroute value to an approach value. RNAV approach must have a HIGH nav accuracy showing with 0.3 nm value on the PROG page before beginning the approach to ensure that the FMGC accurate enough for an RNAV approach. Less than required accuracy will create a NAV ACCURACY DOWNGRADE message on MCDU. You may also get a GPS PRIMARY LOST message which indicates that the GPS signal from an MMR has been lost. If you get either message you must select the autopilot on the side of the operative FMGC. This will allow you to continue the RNAV approach. If both FMGC’s display an error message or you get an FM/GPS POS DISAGREE ECAM you must go around.

 

Ensure HIGH is showing on PROG for nav accuracy. Ensure the “hockey stick” (descent arrow symbol) is visible on ND for start of descent. Ensure APP NAV and FINAL are showing on FMA. Remember “High Hockey Finals”

 

Note: vertical guidance from F/D and “brick”, lateral guidance from F/D and ND.

 

3-2-1 – plan to extend landing gear at 3 miles from FAF, extend flaps 3 at 2 miles from FAF and extend flaps FULL at 1 mile from FAF. At start of descent ensure that missed approach altitude is set. Ensure FINAL is now showing on FMA. When visual on runway is acquired turn off autopilot (at least by MDA). The autopilot will automatically disconnect at DA minus 40 ft. if not off sooner.

 

Note: PM makes 100 above and minimums calls. All other auto callouts available. When the autocallout makes the 500 ft. call the PM should not make the normal Ref + and sink calls as it is commonly very close to the minimums call and can be too confusing.

 

i Airbus Gotcha’: Be sure to get down to final approach altitude prior to FAF to capture from below!

 

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VOR and LNAV RNAV Approaches

 

These two non-precision approaches are flown using RNAV procedures. In both cases the “brick” will be available for vertical guidance. Remember that these approaches are designed by the FAA as “drop and drag” or “dive and drive” utilizing an MDA (minimum descent altitude). The Airbus is using it’s technology to create an artificial glideslope that allows this normally unstabilized approach  to be stabilized. The 50’ pad is added to allow descent to the MDA and then to recognize that the runway is not in sight and begin go-around procedure without busting the hard MDA limit. In actual use the procedure is exactly like the full LNAV-VNAV RNAV approach and the presentation is exactly the same as well.

 

LVAV RNAV approaches will be flown just like RNAV LNAV-VNAV approaches except with the following changes:

 

Ø      LNAV RNAV must add 50’ to the MDA

 

Note: do not add the 50’ when noted on the approach. The verbiage will be similar to the following:

 

“Only authorized operators may use VNAV DA(H) in lieu of MDA(H)”

 

Another way to say this is that the LNAV RNAV approach is flown exactly like the RNAV LNAV/VNAV approach except when the additional verbiage is not added.

 


VOR approaches are a little more different. For VOR approaches use the RNAV LNAV-VNAV procedures except:

 

Ø      NAV must be utilized for approach VIAs (do not select APPR until cleared for approach and intercepting the intermediate segment)

 

Ø      A coded VNAV flight path angle (FPA) in the FMGC is required for the final approach segment.

 

Ø      Raw data must be monitored by the PM. Must remain within 5° of course.

 

Ø      Do not change RNP on the PROG page

 

Ø      NAV accuracy downgrade does not require a missed approach

 

Ø      Add 50’ to the MDA(H)

 

Note: do not add the 50’ when noted on the approach. The verbiage will be similar to the following:

 

“Only authorized operators may use VNAV DA(H) in lieu of MDA(H)”

 

Raw data will be monitored by manually tuning the PM’s RADNAV page to the VOR. Select VOR identifier on PM’s side. (note: you should not tune the PF manually unless the procedure requires it so that autotuning will be allowed on that radio).

 

Position PM VOR selector to VOR.

 

Both pilots should continue to use the PF’s NAV display to monitor approach progress and improve situational awareness.

 

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