Add route detail

docs/flight-planning/routeselection.md

@@ -4,29 +4,37 @@
 
 --8<-- "includes/abbreviations.md"
 
-If you intend on remaining outside controlled airspace and away from busy areas & major obstacles, you can generally select the route of your choice. However, if you are planning to enter CTA or visit a major aerodrome, careful route selection will make it considerably easier for ATC to clear you as requested.
-
-## ERSA Preferred Routes
-- Preferred routes from A to B in the list first, then:  
-- Use as starting point to exit/enter busy TMAs, then use other route planning to connect the two
-- If required route is less than ideal, consider departing VFR/OCTA
+If you intend on remaining outside controlled airspace and away from busy areas & major obstacles, you can generally select the route of your choice. However, if you are planning to enter CTA or visit a major aerodrome, careful route selection will make it considerably easier for ATC to clear you as requested. A number of [third-party tools](#use-of-third-party-tools) exist to help with route selection but each have shortcomings and limitations, so it's helpful to be aware of how to perform this task manually.
 
 ## VFR Route Selection
-- Frequent navigation points to assist with visual navigation
-- Routes keeping aircraft clear of CTA/PRD, even if navigation isn't accurate (i.e. applying buffer to these restrictive airspace sectors)
-- Considering availability of airways clearance and Plan B if clearance not available
+When operating VFR, you are required to determine your position with a visual fix every 30 minutes (see [VFR Navigation](../navigation/vfrnavigation.md#navigation-requirements) for more info), so it is important that you plan your route with enough identifiable landmarks to allow frequent visual fixes. Using a VTC, VNC, or WAC (available on the AIP website), plot your departure and destination airports, then assess any route requirements to remain clear of obstacles, CTA, or PRDs. From there, select a route which will provide easy visual navigation, with frequent landmarks (such as mountain peaks, lakes, river junctions, towns, racetracks, etc) on and either side of your planned track.
+
+When operating near CTA or PRDs, apply a conservative lateral buffer or plan a level which remains clear of the boundary. If ATC see you tracking towards airspace without a clearance, they're likely to send you a 'contact me' request.
+
+If you plan to enter or transit CTA, especially around major Class C aerodromes, plan a backup route which remains OCTA, in case an airways clearance is unavailable.
 
 ## IFR Route Selection
-- Use of ERC H or L depending on intended cruising altitude
-- Awareness of grid and route LSALTs where aircraft performance may suffer in event of engine failure or icing
+IFR flights are generally planned along pre-defined airways, joining ground-based navaids or RNAV waypoints together along surveyed paths. This provides pilots with terrain/obstacle clearance assurance and helps manage traffic in busy terminal areas by defining a designated inbound and outbound track. Some airways are designated as one-way tracks, while others allow traffic to utilise it in both directions.
+
+Pilots should use an ERC in conjunction with a TAC around major aerodromes to determine the best route. For operations at or below FL200, use the ERC-L (low). Operations above FL200 should use the ERC-H (high). Some remote aerodromes aren't serviced by airways, so it may be desirable to plan direct to an appropriate fix instead.
+
+When planning a route, consider any airspace requirements (particularly when operating to, from, or in the vicinity of major aerodromes) and ensure you comply with the [ERSA Flight Planning Requirements](#ersa-flight-planning-requirements) as detailed below. Also consider the terrain you'll be flying over. During the winter months, icing can become a serious threat to aircraft without ice protection equipment and an alternate route may need to be planned to avoid areas of high terrain, allowing the aircraft to operate in the warmer air at lower altitudes. Each degree of latitude/longitude on an ERC-L is divided into a grid, and a Grid LSALT is published for each square denoting the lowest safe altitude for operations in that area. Pilots can use these Grid LSALTs to ensure they'll remain above any limiting obstacles/terrain, even if they need to deviate off their planned route.
+
+### ERSA Flight Planning Requirements
+The ERSA Flight Planning Requirements (FPR) document lists required tracking points and vertical restrictions which help manage traffic flow into and out of busy aerodromes. Ensure that your planned route complies with any restrictions imposed by the FPR. If your planned departure and destination aerodrome (or initial tracking points) are not listed in the document, you can assume that no planning requirements apply. In this case, plan a route in accordance with the advice above to respect any one-way airways or other planning requirements.
+
+!!! tip
+    If the required route listed in the FPR is undesirable (e.g. it adds significant track miles) and the weather is suitable, consider departing VFR or remaining OCTA until you are outside the terminal area.
 
 ## Altitude Selection
 - Hemispherical levels
 - VFR +500ft levels
+- Safe altitude above terrain
 
-## Designated Remote Areas
-- Reference to CAOs
-- Requirement to carry survival equipment (not really a consideration for flight sim)
+<figure markdown>
+  ![Grid LSALTs (circled) over Flinders Island for each green grid square](img/gridlsalts.png){ width="700" }
+    <figcaption>Grid LSALTs (circled) over Flinders Island for each green grid square</figcaption>
+  </figure>
 
 ## Use of Third-Party Tools
 - Warning about use of SimBrief routes