Thursday, April 23, 2020

Instruments : Approaches

In general
  • Approach Title:
    • If the procedure ends in "A, B, C..." there are multiple circling approaches
    • If the procedure ends in "Z, Y, X..." there are multiple ST-IN approaches
  • Briefing:
  • Chart review at
  • Charted Visual Approach (boldmethod)
  • ILS
    • If your right wing is on the shaded part of the feather, then steering is "right" (correct). If it's your left wing, steering is "wrong" or back course.
  • LP approach
  • LPV and LNAV/RNAV, the differences:
    • They’re both GPS approaches with vertical guidance, but similarities end there.
    • LPV
      • Use WAAS/GPS, but NOT precision.  They are APV (approach with vertical guidance) - it was less admin and cost to call them APVs.  BARO-aided GPS doesn’t suffice.
      • They get more sensitive as you get closer and are about 700’ at the threshold (like an ILS), but they essentially turn linear after the threshold
      • Can’t use precision alternate minimums.  You need WX that meets LNAV, circling or LNAV/VNAV DA
      • Actually, first GPS approaches with vert guidance – designed for BARO-aided GPS
      • Difference?  Don't have increasing angular guidance as you approach the runway.  They decrease to 0.3 nm sensitivity when w/in 2nm of FAF – all the way to MAP.
      • The lowest they can go is 250’ above touchdown, but due to obstacles it’s often higher
    • LNAV +V
      • Only shows on your GPS (if able), not on plates.  And the vertical glide path is advisory only…you still need to fly step-down altitudes and MDA
  • RNAV (GPS) Approaches:
    • Great explanations by:  FAA and boldmethod
    • Remember, even with vertical guidance, and while using a DA (decision altitude), these are NOT considered precision approaches.  They are APVs (APproaches with Vertical guidance).  If you remember "guidance" and "glideslope", it will help separate these from precision approaches.
    • LNAV - Lateral Navigation (uses an MDA)
    • LNAV/VNAV - Lateral Navigation/Vertical Navigation (uses a DA)
    • LP - Localizer Performance w/o Vertical Guidance (uses an MDA)
    • LPV - Localizer Performance w/ Vertical Guidance (uses a DA)
    • RNP, written "RNAV (RNP)", see below
  • RNP approach (FAA page)
    • When you see RNP in the approach label, it can be interpreted as 'authorization required' because in reality, any RNAV has some RNP.
  • Segments:
    • What is considered the Initial Approach Segment on an approach?
      • The initial approach segment begins at the initial approach fix and ends where it joins the intermediate approach segment.
    • What is considered to be the Intermediate Approach Segment?
      • The intermediate segment (normally aligned within 30 degrees of the runway) begins at the intermediate point and ends at the beginning of the final approach course.
    • What is the Final Approach Segment?
      • The final approach segment for a precision approach begins where the glide slope is intercepted at the minimum glide slope intercept altitude shown on the approach chart;
      • The final approach segment for a non-precision approach begins at either a designated Final Approach Fix (FAF) or at the point where you are established on the final approach course.
      • When the FAF is not designated, such as where there is a VOR or NDB on the field of intended landing as published, the Final Approach Point (FAP) is where the procedure turn intersects the final approach course inbound.
    • What is considered the Missed Approach Segment?
      • The missed approach segment begins at the MAP and ends at a designated point.
  • Understanding GPS approaches (Pilot Workshop)
  • AIM: cross DER > 35’, 400’ before first turn, 200 FPNM until minimum IFR altitude*
    • 200 FPNM = 233 FPM @ 60 GS, 267 @ 80, 300 @ 90
    • * unless specified different (crossing alt, DP) turn @ higher altitude or @ fix
  • DPs and ODPs (ODPs are normally narrative)
    • Obstacles w/in 1nm & < 200’ tall are “low close-in obstacles” and are generally NOT factored in ODP
  • Minimum takeoff WX?  There isn’t, but a technique is highest published circling mins 
- FIG -

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