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| title: IFR Enroute Navigation | ||
| title: IFR Enroute Navigation | ||
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| --8<-- "includes/abbreviations.md" | ||
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| ## Route Planning | ||
| - Link to Flight Planning section | ||
| - Important to flight plan according to the equipment onboard | ||
| - Requirement for IFR aircraft to be equipped with GNSS | ||
| - [Link to Flight Planning section](#) | ||
| - **Flight Planning Basics:** When planning an IFR flight, make sure you plan using the equipment onboard and what you as a pilot are capable of using. | ||
| - **GNSS Requirement:** In Australia, aircraft must be equipped with GNSS if flying under IFR. However, you can fly non-GNSS in Australia if your aircraft is equipped with traditional navigation systems like VOR or NDB for training. | ||
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| ## Navigation Tolerances and Track Keeping | ||
| - **Track Keeping:** When flying IFR, it’s essential to stay as close to your planned track as possible. Navigation tolerances are applied to ensure that you remain within a safe corridor, keeping you clear of other aircraft, terrain, and restricted airspaces. If you notice you’re off-track, take immediate action to correct it and notify ATC. | ||
| - **Order of Precision:** When navigating, use the most precise navigation aid available to you unless training. The order of precision is as follows: Localiser (ILS), GNSS, VOR, and then NDB. Always aim to use the best available method available based on location to maintain accuracy. | ||
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| ## Area Navigation | ||
| - Use of GNSS and other area-based nav systems (INS) | ||
| - Where possible, cross check the next track and distance at station passage of each waypoint | ||
| - | ||
| ## Ground-Based Navaids | ||
| - Cone of confusion | ||
| - Changing sensitivity based on distance from station | ||
| - Range of navaids (replace VOR/DME table, indicate location of NDB ERSA entry) | ||
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| ## Lowest Safe Altitude (LSALT) | ||
| - Requirement to remain above LSALT, unless: | ||
| - Visual by day | ||
| - NVIS by night | ||
| - Pilot calculated lowest safe | ||
| - Types of LSALTs: | ||
| - Route LSALT (consideration when flight planning) | ||
| - Grid LSALT | ||
| - Aerodrome MSA | ||
| - **Using GNSS and INS:** GNSS and other area-based navigation systems like INS help you navigate accurately. Always cross-check the next track and distance as you pass each waypoint to ensure you're on the right path. | ||
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| ## Position Fixing | ||
| **Cross-Checking:** At each waypoint, double-check your next course and distance, especially when passing over a navigation station. This ensures you stay on track and avoid getting lost. You need positive fixes with waypoints. | ||
| - **Positive Fix:** A positive fix is a confirmed position of your aircraft. You can get a positive fix by: | ||
| - Passing directly (station passage) over a navigation aid like an NDB, VOR, or DME. | ||
| - Intersecting two or more position lines (like radials from VORs) that cross at a good angle (at least 45°). | ||
| - Using GNSS | ||
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| ### Station Passage | ||
| Station passage occurs when your aircraft flies directly overhead a navigation aid like a VOR, NDB, or ILS. This indicates you've passed the aid and need to switch to the next leg of your route. | ||
| - **VOR Station Passage:** The "cone of confusion" is often a good way to know you've experienced station passage, especially with VOR and ILS. As you fly over the station your instruments might fluctuate. VOR station passage occurs when the TO-FROM indicator. | ||
| - **NDB Station Passage:** ADF needle will swing rapidly, showing that you've passed the station. | ||
| - **GNSS Station Passage:** Your GNSS unit will show that you’ve passed it and will prompt you to navigate to the next waypoint. | ||
| - **DME Station Passage:** When the DME stops decreasing and starts increasing. | ||
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| ## Ground-Based Navaids Limitations | ||
| - **Changing Sensitivity:** As you move farther from a navigation station, the signal sensitivity changes. This means the accuracy of your navigation can decrease with distance, so always be mindful of how far you are from a station. Also as you get closer to the aid, often the sensitivity increases. | ||
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| ## VOR and NDB Ranges | ||
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| ### VOR Ranges | ||
| | Aircraft Altitude (ft) | Approximate Range (nm) | | ||
| |------------------------|------------------------| | ||
| | 1,000 | 40 | | ||
| | 5,000 | 85 | | ||
| | 10,000 | 120 | | ||
| | 20,000 | 175 | | ||
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| ### NDB Ranges | ||
| NDB ranges are listed in the ERSA entry for the airport. It provides the range of the NDB and may separate day and night distances. | ||
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| ## LSALT | ||
| The LSALT is the minimum altitude that ensures you are safely above any terrain or obstacles along your route. Always remain above the LSALT unless your departing or landing. If you deviate from your planned track or need to divert, it’s essential to recalculate your LSALT based on the new route. If you request a visual departure, you must ensure the cloud base allows your aircraft to climb in VMC to the LSALT or MSA. You must maintain ATC-assigned tracks/headings and obstacle clearance during the departure. | ||
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| - **Types of LSALT:** | ||
| - **Route LSALT:** This is the LSALT calculated from the enroute or terminal area charts for an airway. | ||
| - **Grid LSALT:** A grid square on the ERC or TAC charts. Often used for planning diversions. More conservative than Route/MSA/Pilot calculated LSALTs. | ||
| - **Aerodrome MSA:** MSA exists for aerodromes that have an instrument approach and are often depicted on approach plates as circles, typically separated into a 25nm section (which can be further segmented into sectors) and a 10nm section. | ||
| - **Pilot Calculated LSALT:** Pilot calculated LSALT is where a pilot calculates an LSALT. Often used for departures or approaches from aerodromes without an instrument approach. This requires considering the highest terrain or obstacle in a segment depending on the navigation aid used. | ||
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| ### Lateral Tolerances for LSALT | ||
| "Lateral" in this context refers to the horizontal distance on either side of your planned track that you need to consider to ensure safe clearance from obstacles. This is the area in which you need to consider your highest obstacle and apply the LSALT vertical tolerances to and changes on the navigation aid used. | ||
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| - **RNP 2 / GNSS (5nm Radius):** The GNSS navigation standard for VATPAC should consider an area within a 5nm radius from your track when calculating LSALT. GNSS LSALT is very confined to reflect its accuracy. | ||
| - **Navigation Using Radio Aids (50nm Cone):** VORs or NDBs have a 50nm cone extending outward from your track. Then add a further 5nm radius around the edges. | ||
| - **VMC Night (10nm Radius):** When navigating at night VFR without the assistance of navigation aids, you need to consider 10nm either side of your track. | ||
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| ### Vertical Tolerances for LSALT | ||
| Using the lateral tolerance from above, find the highest obstacle for that area, then: | ||
| - If the highest obstacle in your area is over 360 feet above the terrain, add 1,000 feet to that obstacle’s height to determine the LSALT. | ||
| - If the highest obstacle is less than 360 feet above the terrain or there are no obstacles, add 1,360 feet to the terrain elevation for your LSALT. | ||
| - If the terrain or obstacle height is less than 500 feet, your LSALT should not be lower than 1,500 feet. | ||
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| ### Night NVIS Operations | ||
| Some flights are authorized to operate below the published LSALT at night or in IMC. In such cases, the pilot in command is responsible for avoiding terrain. This might happen, for example, with NVIS operations. NVIS is a technology that allows pilots to see in low-light conditions, primarily used by military and special operations pilots. | ||
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