Here's the best of what I know - but I'm NOT an expert...
If you book UA
metal under a UA
flight number you can use a 2011 SWU as long as you book in fare class W or above, and there's upgradeable space (I believe you need to find space available in fare class 'RN' when selecting your flights on UA
.com) and the transaction can be performed immediately and electronically. (2010 PMCO SWUs have no fare class restriction...)
If you book LH
metal you would only be able to use a paper SWU (issued by calling UA
and having them mail the SWU to you - takes up to 2 weeks) and these are restricted by fare class - confusingly: LH
restricts different fare classes from UA
- and you can only use them on a stand-by basis on the day of travel and IIRC LH
advises the pax to check in 3 hours in advance when trying to use an SWU!
Just as a side note, I would say always try to book the flights under the code of the operating carrier when trying to perform 'unusual' transactions - I've been burned several times by booking flights under all UA
flight numbers and then not being able to access reservations, seat assignments, upgrade requests, etc, etc because neither UA
nor the operating carrier's website will recognize the codeshare flight number...
Oh, and since 2012 Mileage Plus changes SWUs have a new abbreviation: GPU - just in case you see that terminology used in another forum!)