RVSM Airspace

The Western Hemisphere implemented RVSM airspace on January 20, 2005.  Explain what RVSM airspace encompasses and what specific requirements an aircraft and flight crew must have in order to enter RVSM airspace.  Discuss what happens and what action the flight crew must take if one of the required components fails while the aircraft is in RVSM airspace.  Lastly, give a brief explanation of why the switch to RVSM took place after the old system of 1000 ft separation up to FL290 and 2000 ft separation above FL290 had worked so well since its inception in 1958.