RNAV Approaches Flashcards
What is RNAV (area navigation)
RNAV (Area Navigation) is a method of navigation which permits the operation of an aircraft on any desired flight path; it allows its position to be continuously determined wherever it is, rather than only along tracks between individual ground navigation aids (Victor Airways).
RNAV was developed to provide more lateral freedom and thus more complete use of available airspace.
What is RNP
Required Navigation Performance (RNP) equipment provides onboard navigation capability that allows crews to fly aircraft along a precise flight path with exceptional accuracy, and most importantly, the ability to determine aircraft position with both accuracy and integrity.
What is PBN
Performance Based Navigation (PBN) is comprised of Area Navigation (RNAV) and Required Navigation Performance (RNP) and describes an aircraft’s capability to navigate using performance standards.
PBN will also enhance aircraft safety, capacity, efficiency, and reduce costs.
•Required Navigation Performance refers to the level of performance required for a specific procedure or a specific block of airspace. (Think of it as accuracy)
•Example: RNP 2 means the aircraft will be within 2.0 NM of the centerline of the route 95% of the time
GPS RNP
•GPS will operate in three modes: En Route, Terminal and Approach
•GPS performance (accuracy) will automatically change depending on the mode of operation
•En Route – Terminal within 31nm from airport.
•Terminal – Approach no later then 2nm from final approach waypoint (FAWP)
Linear and angular sensitivity
Linear sensitivity: Similar to GPS
en route navigation.
Angular sensitivity: Similar to
localizer deviation. Becomes more sensitive the closer you get to the runway
LNAV
•LNAV: This term refers to “Lateral Navigation.”
•LNAV approaches are the simplest GPS approach.
•It’s a non-precision approach that requires only an IFR certified GPS.
•WAAS- enabled GPS units might provide advisory guidance in association with LNAV. (LNAV+V – more on this later)
•An LNAV approach is always a line of minima on any RNAV (GPS) approach plate.
•LNAV approach’s have MDA’s as low as 400ft AGL.
LNAV+V
•LNAV+V: This term refers to “Lateral Navigation with advisory vertical guidance.”
•The vertical guidance is artificially derived from WAAS
•Is not officially sanctioned by the FAA, which is one reason you will not see it on an approach plate.
•LNAV+V approaches use LNAV minima but offer a stabilized approach and eliminates the “chop-and-drop” method.
•Statistically, you are five times more likely to have CFIT accident on a non-precision approach than on one with vertical guidance.
•Example: GPS 23 P08
•It’s possible a +V could take you below step-down minimums, so you need to
LP
LP: This term refers to “Localizer Performance.”
WAAS equipment is mandatory for LP minima.
LP lateral sensitivity increases as an aircraft gets closer to the runway. (angular sensitivity)
LP approaches have MDA’s as low as 300ft AGL
LNAV/VNAV
•LNAV/VNAV: Lateral Navigation and Vertical Navigation
•LNAV/VNAV utilizes approved vertical guidance offered by WAAS or approach certified baro-VNAV systems
•If using a baro-VNAV system, the pilot must check for any published temperature limitations.
•Minimums are shown as DAs because the approaches are flown using an electronic glide path.
LPV
•LPV: not an acronym, but you might think of it as “localizer performance with vertical guidance.”
•Important: Your aircraft must have WAAS avionics equipment approved for these approaches in order to fly to LPV minimums.
•LPV is nearly identical to flying an ILS to help pilots transition their flying skills
•LPV approaches have DA’s as low as 200ft AGL
•IMPORTANT: All RNAV (GPS) approach minima are considered non-precision in the eyes of the FAA. However, per the ACS “LPV minimums can be used to demonstrate precision approach proficiency if the DA is equal to or less than 300ft HAT.
Flying RNAV approaches
•Within 2 NM of the FAWP with the approach mode Activated, the GPS mode will switch to APPR if RAIM is successful
•If a RAIM failure is detected prior to the FAWP, you should not descend to the MDA, but should proceed to the missed approach waypoint (MAWP), perform a missed approach, and contact ATC as soon as practical.
What to do when you lose WAAS
•Can continue approach but change your minimums
•Change minimums to LNAV
•Only descent to LNAV minima
