ZED ( Zonal Employee Discount ) Fares can be much better than ID90s. They are charged based on miles flown rather than a percentage of commercial fares. I really didn't understand them until I started my present job. I like them much better than ID90s though because they have some flexibility. They can be changed over to another carrier who accepts ZED fares.
On my last trip back to the States I looked at buying an ID90 on Delta to fly from SLC to MIA. I forget the exact price quoted but our staff ticket agent asked me if there was some reason that I chose Delta. I said, " no, not really, just thought they might have more flights per day ". He went on to explain that using a ZED fare on the same city pair with Continental would save me almost 50%. In the USA I think Continental, USAirways, Northwest, and AA are the only carriers that use the ZED system.
There are 9 distance zones under ZED. Each zone refers to the distance flown in Ticketed Point Mileage ( TPM ). Under each travel type, there are three fare levels: Low (ZL), Medium (ZM), and High (ZH). Each of these fare-levels depends on the bilateral agreements with individual carriers. Infants below age 2 travel free.
Your company should have a list of agreements with other carriers for you to check.
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