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In ICAO's 8160 "Aircraft Operations" manual there is a term called "track guidance", for which I can not find any clear definition.

A few examples:

Departure Procedures 3.1

3.1.1 There are two basic types of departure route: straight and turning.

3.1.2 Track guidance shall be provided:

a) withing 20.0 km (10.8 NM) from the departure end of the runway (DER) for straight departures; and

b) within 10.0 km (5.4 NM) after completion of turns for turning departures.

3.1.3 Surveillance radar may be used to provide track guidance.

..

3.2.2 Types of Straight departure

b) straight departure with track guidance:

1) facility ahead or behind; and

2) offset (track parallel/track offset/track crossing).

..

1.6 TRACK GUIDANCE

1.6.1 Track guidance should normally be provided for all phases of flight through the arrival, initial, intermediate, final and missed approach segments. When track guidance is provided, the appropriate segment shall lie within the established coverage of the navigation facility on which the track guidance is based.

Judging from the context in which track guidance is mentioned, I would say that it refers to conventional navaid-based procedures, where the aircraft needs navaid facilities in order to keep on track.

All things considered, does the term track guidance have any meaning for RNAV/RNP procedures? Are RNAV/RNP procedures considered procedures without track guidance?

Any clarification would be appreciated.

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ICAO Doc 8168 "Procedures for Air Navigation Services - Aircraft Operations - Volume I - Flight Procedures" states under 2.1.3 Types of SID:

Track guidance may be provided by a suitably located facility (VOR or NDB) or by RNAV.

To answer your question: RNAV/RNP SIDs are considered procedures with track guidance.

The better your tracking is the smaller the protection area required (especially for turn construction). So flying inbound or outbound a navaid or having RNAV capabilities greatly increases your precision und therefore allows for procedure construction with relaxed climb gradients in areas with difficult obstacle situation.

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  • $\begingroup$ Thank you Chris, I appreciate your input! Just one small clarification: If both conventional and RNAV/RNP SIDs are procedures with track guidance, then under what circumstances is a procedure considered procedure without track guidance? Could it be eg SIDs with vectoring? $\endgroup$ – Vector Zita Sep 16 at 11:59
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    $\begingroup$ @VectorZita "without track guidance" simply means that you have no indication in the cockpit which tells you your deviation from the intended track. Something like a SID "At 800ft turn right heading 090. Intercept and proceed on R180 XYZ-VOR." The altitude and heading portion has no track guidance. The altitude depends on your aircraft performance (high or low rate of climb). The track flown resulting from the heading is heavily dependent on the wind. So these parts are considered to be "without track guidance". The radial is a form of track guidance so there the smaller safety zones apply. $\endgroup$ – Chris Sep 16 at 12:12
  • $\begingroup$ In other words, even if RNAV/RNP SIDs are considered procedures with track guidance, in special cases like a VA leg of a departure procedure, these "special" portions of the RNAV/RNP SID have no track guidance? Because the definition of a VA leg is "heading to an altitude". $\endgroup$ – Vector Zita Sep 16 at 13:10

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