not entirely true imho.
Hedged fuel means an option to buy fuel at a given price. If this option is not excercised you loose a downpayment, but in this case where a barrel has dropped by 50%, one could buy at that new rate and only loose the downpayment
If the downpayment is 10% at a barrel rate of 140 dollars and the current rate is 70, the max cost would be 94.
I think the surchae is in part used to cover the cost of the rising fuel when no surcharge was charged yet as well as the downturn in ticket sales