Also, it's possible there will be a time when the cash
price of a coach ticket in the above example is less than $ 600.
Surcharges on business and first class tickets can be approximately the
price of a coach ticket, and there are even cases where the fuel surcharges on a coach ticket can approach or exceed its cash price.
The Flying Blue program isn't great normally — while they have a reasonable award chart (50,000 miles roundtrip for coach to Europe and 100,000 miles for business), their fees and fuel surcharges can easily cost more than the price
of a coach ticket.