ICAO v RVSM

[xfeed]

I was hoping that some one could explain what ICAO and RVSM mean and what the difference is between them. Do different countries adopt one or the other? I appreciate any responses.

Cheers!

[chiglet]

International Civil Aviation Organisation
Reduced Vertical Separation Minima
One is a "rulemaker" [sic] and the other is a thousand feet vertical separation above Flight Level 290 [if so equipped]
watp,iktch

[Old Smokey]

xfeed,

chiglet has given you the correct de-code of the 2 abbreviations. To go a little further....

Under ICAO rules, IFR aircraft flying Easterly Tracks (000° to 179°) fly at Odd thousands of feet, and aircraft flying Westerly Tracks (180° to 359°) fly at Even thousands of feet. This means 2000 feet vertical separation between same direction traffic, and 1000 feet vertical separation between opposite direction traffic. In recognition of reduced Altimeter accuracy at the higher levels above 29000 feet, this vertical separation is doubled to 4000 feet (same direction) and 2000 feet (opposite direction) respectively. Only Odd levels are used after F/L 290, e.g. 310, 350, 390 etc. for Westerly traffic, and 330, 370, 410 etc. for Easterly traffic.

Later generation altimeters of much improved fidelity have made possible the implementation of Reduced Vertical Separation Minima (RVSM) in some states, where essentially, the 4000/2000 separation is dropped above F/L 290, and the standard 2000/1000 separation is extended from F/L 290 to F/L 410, i.e. 300, 320, 340, 360, 380, and 400 are all useable Flight Levels for appropriately equipped and approved aircraft. Above F/L 410, ICAO separation rules again.

To answer the last part of your question, NO, RVSM is not universal. Some states use it fully, some use only ICAO, and some use a mixture of both in different airspace regions. And then, some states, like China, still use Metric Altimetry, with their own separation standards.

There's more to be said, but I think that that covers the basics.

Regards,

Old Smokey

[justcoolen]

Old Smokey paints a very good picture. However the rules change for the North Atlantic. Levels are swapped throughout the North Atlantic Track Structure during different times of the day/night. Eastbound tracks are usually fl320-400 (0100-0800Z)within the tracks, and Westbound levels are usually 310-400 (1130-1900Z). Levels vary North or South of the tracks depending on time for 30w, and direction of flight during the East or Westbound flow.

[xfeed]

Thank you Chiglet and Old Smokey for you answers. Once again, I appreciate your in-depth explanation to my questions Smokey. It is all much clearer now.

Cheers!