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When do you need a second alternate? When do you need a departure alternate ? What is RVSM?
Sigiloso
When for destination and first alternate is reporting MVFR, you need a departure alternate when weather is not best then the approach back into original airport, RVSM is reduced vertical separation where traffic separate is reduced from 2,000 to 1,000 to allow more traffic in the airspace between FL290- FL410