aircraft navigation basics

This page covers important topics related to aircraft navigation:

• Equipment suffixes (7110.65 2-3-9)

• RVSM Airspace (7110.65 4-5-1)

• Altitudes based on the direction of flight (7110.65 4-5-2)

• Lowest Usable Flight Level (7110.65 4-5-4)

• As a clearance delivery controller, it is also your responsibility to know what the different types of equipment suffixes are and what each one of them does.

• You do not need to memorize all of them, but it's expected that you know the most common ones found on VATSIM.

  • Some common ones you may see on the network include: /L, /G, /A, /W, and /Z (see below for more details)

• For each equipment suffix take into account the aircraft’s:

  • Navigation capabilities

  • Transponder capabilities

  • RVSM capability

Most Common Equipment Suffixes

/L: RVSM, GNSS, Transponder with Mode C

• Capable of FL290 or above, has GPS. Most modern airliners are in this category.

/G: No RVSM, GNSS, Transponder with Mode C

• Restricted to flights below FL290¹, has GPS. This is common for smaller planes with modern avionics.

/A: No RVSM, DME, Transponder with Mode C

• Restricted to flights below FL290¹, navigation by VOR/DME capability. This is common for smaller planes without GPS.

/W: RVSM, No RNAV, No GNSS, Transponder with Mode C

• Capable of FL290 or above, navigation by VOR/DME capability. This is common for older airliners without RNAV.

/Z: RVSM, RNAV, No GNSS, Transponder with Mode C

• Capable of FL290 or above, basic RNAV (i.e. INS, may be able to use RNAV SIDs or STARs), and VOR/DME. This is common for older airliners that don't have GPS, but have an IRU that still allows them to navigate with some RNAV capability².

1: For equipment codes restricted to flights below FL290 (no RVSM), if the pilot wants to fly above FL290, coordinate with the En-Route controller.

2: RNAV can get complicated. INS is very precise but its accuracy drifts over time, so it needs another navigation system to provide corrections. GPS is one possible source of these corrections, but another source could be DME. FAA equipment codes don't get into more detailed capabilities like this, but ICAO equipment codes do.

RVSM

What does RVSM stand for? What does it mean to us?

• RVSM stands for Reduced Vertical Separation Minima.

• RVSM is the reduction of required vertical separation between aircraft from 2,000 to 1,000 feet, starting at FL290 and up to FL410. 

• Keep in mind that not all aircraft are RVSM capable. Pay close attention to the aircraft’s equipment suffix!