GS/Global Services is the highest tier of elite status. It is by invitation -- the invite criteria is not public but seems to require substantial annual spending with UA both in terms of absolute dollar amounts and purchasing higher fare classes (higher cpm - cents per mile). There are also reports of GS status being comped by UA Marketing to VIPs in companies who sign corporate travel deals with UA. The sole published way to qualify is to become a 4MM, having flown 4 million BIS miles on UA metal (plus additional grandfathered credits at the time of the UA/CO merger).

GS have significantly enhanced services / benefits over 1Ks. There is little said publicly by UA on GS benefits and/or qualification.

Last years' thread, Consolidated Global Services Thread - Qualifications, Benefits and Q & A [2016]
Thread on 2017 Global Services Notifications
Thread on 2017 Qualifying Discussion

Known facts from United:

Known Award and Upgrade Benefits:

All benefits noted below require calling a GS agent:

• GS can create saver economy award space (XN) if T inventory is available.
• GS can create saver business award space (IN) if R inventory is available.
• GS can upgrade economy awards (XN or YN) into Business First with a GPU if PN inventory is available.
• GS can upgrade business awards (IN or JN) into Polaris First with a GPU if ON inventory is available.
• GS can confirm any waitlisted instrument-supported upgrade under T-72 hours provided 2 seats remain for sale afterwards and they are at the top of the waitlist
• GS can create saver Polaris First (O) space at T-72 hours if they are already booked in saver business (IN), provided one seat remains for sale after
• GS are entitled to one saver award seat in the same class of service with their purchase of any premium fare. GS agents can open space if it is not available. UPDATE: as of 7/21/17 must have >2 for sale within 72hrs of flight
• GS can upgrade a companion from coach to biz when flying on a paid biz fare, even if R or PN is not available, as long as J/F>1. Companion needs to be W or greater intl.
• (Only ONE of the two above options can be exercised per premium fare.)
• GS cannot double upgrade. Economy -> PN -> ON is not allowed. *Some reports of TOD being offered at OLCI.
• GS can buy up from Basic Economy fares, which is usually forbidden