![]() ![]() RAIM: Pilots using GPS with no WAAS augmentation should (not shall) use the RAIM prediction to ensure approach level RAIM availability at destination or alternate for the ETA (+/-15mn) before takeoff and prior to commencing approach. Missed Approach Waypoint definition: MAWP (Missed Approach Way Point), usually located over runway threshold. It consists of a series of waypoints in a “T” or “Y” pattern (generally), thus eliminating the need for a procedure turn. An overlay approach can be conducted without the need to monitor the underlying nav-aid, and is also permissible when the underlying nav-aid is temporarily out of service.Īn approach labled RNAV (GNSS) RWY XX – GNSS-based RNAV approach – is another type of NPA LNAV approach. This kind of approach is extremely useful, as it allows a pilot to conduct a straight-in approach via the FAF (while respecting minimum sector altitudes). In one case, an approach labeled such as (GNSS) VOR RWY XX – otherwise known as a GPS Overlay Approach – a traditional VOR or NDB-based approach which has been approved to be flown using the guidance of an IFR-certified GPS (LOC and LOC/BC are not approved for overlays). WAAS may provide vertical guidance during the approach but it is important to recognize that this guidance is ADVISORY only. They can be flown using any IFR-certified GPS or WAAS-augmented GPS. RNAV and Overlay Approaches with Lateral Guidance OnlyĪ LNAV approach can be considered as a regular Non-Precision Approach. It does not provide or define any vertical path but instead must be flown using the step-down altitudes using a regular barometric altimeter. Some aircrafts use multi-sensor FMS+, but were rarely found in General Aviation until the recent marketing of glass cockpits. There are two main modes of vertical guidance: BARO VNAV or WAAS-augmentation (Class 2/3). ![]() This is where it becomes extremely important for you to know exactly what equipment is available to you and what it allows you to do when used for approach purposes. However, they also bring in a completely new dimension that pilot must understand fully. Vertical Guidance – Benefits and ConstraintsĪpproaches with vertical navigation or guidance offer many safety benefits, including a more stabilized approach and higher success rates. Pilot-made waypoints are only acceptable en-route. All approach waypoints MUST be retreived from the database. NOTE: When you are planning to execute an RNAV or Overlay approach, always ensure that your GPS IFR database is up to date. LPV (localizer performance with vertical guidance – APV).LNAV/VNAV (lateral/vertical navigation – APV).The RNAV is in turn divided in three sub-categories: There are two types of GNSS-based approaches: With the arrival of the new cool kid on the block (GNSS), a new definition has been added to cover approach and landing operations with vertical guidance ( APV) which use lateral and vertical guidance, but do not meet the PA requirements. In the days of old, only two types of approaches existed: Precision Approaches ( PA) and Non-Precision Approaches ( NPA). In simple terms, here are the three main things a pilot needs to know when planning on flying a GPS-based approach: Types of Approaches available (and their requirements) (Source: Transport Canada AIM) Phase of Flight Let’s have a look at the different requirements for each phase of flight. GNSS may be used for all en-route and terminal operations, as long as the aircraft is also equiped with approved traditional systems (such as VOR and ADF) to serve as backup. Avionics also have to meet the appropriate equipment standards and be approved by the governing flight authority (FAA, Transport Canada, etc.) The tolerance tresholds and levels of performance required vary greatly for the use of a GPS module depending on the phase of flight. Although we (the company) have been able and trained to conduct LNAV approaches where applicable, the introduction of VNAV/LPV technology brings up a completely new dimension (yup, 3D approaches!) So training for the use of the GPS for approaches and a quick review of the related rules was incorporated in the ride.īefore we go any further, I would strongly suggest that you read the first part of this article (if you have not done so already) to familiarize yourself with a few terms and basic underlying principles. ![]() As it happens, our fleet of PC12NGs is getting a software update, which will eventually allow us to complete LPVs approaches virtually everywhere. I recently had the “pleasure” to complete my yearly recurrent ride. ![]()
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