AA - Lets you hold for 5 days if more than 21 days to departure. 21 to 7 days they will hold for 3 days. Less than 7 days 24 hours.
USAirways - Lets you hold for 3 days - even within 21 days
United - In Feb United officially stopped allowing hold on award flights - They do offer FareLock which cost $9.99 for 3 days, $14.99 for 7 days on a domestic ticket
there is a workaround by selecting to purchase using your Paypal account and then not signing in - not sure how long that hold will last?
Installing DoNotTrackMe workaround - Only works if you don't have enough miles and the United award includes at least one segment on an airline other than United.
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