Oil rich Azerbaijan is part of the strategically important but fragile South Caucasus where Russia and the US are still competing for influence.
The ex-Soviet republic hosts a pipeline pumping Caspian Sea oil to world markets.
Azerbaijan is locked in a dispute with Armenia over the Nagorno-Karabakh region where ethnic Armenian separatists threw off Azeri rule in a 1990s war that killed about 35,000 people.
The two countries are technically still at war.
Rzayev headed Azerbaijan's air force since 1992.