Originally Posted by hughw

Amex points are a terrible waste to use for air fares or upgrades of one sort or another. But people do it, including my brother-in-law. They never get transferred to an airline that's not a partner such as UA. Basically UA sells an airfare at whatever the market price is and you pay for it with some combination of cash and/or points which typically have a value of from $0.005 to $0.01. So if it cost say, $1000 for an airfare, you could buy it from AMEX for 100,000 points.