At American and Delta, the top services aren’t part of the mileage program, a separate elite tier.
At United, in contrast, their revenue-based status Global Services is actually a true top tier — Global Services members get their upgrades ahead of 100,000 mile flyers, and even trump the usual upgrade priority so that full fare elite passengers fall behind Global Services members (whereas a full fare Silver on a given trip will trump a mid-priced fare 1K in the upgrade queue).
They don’t publish a criteria for earning Global Services status. It’s not based on mileage flown, but revenue for the most part. They give it not just based on your own revenue but also to significant travel influencers who drive the revenue of others (such as through major corporate contracts for which they’re the decision-maker).
Years ago it was separate from Mileage Plus. You could have Global Services members who were merely Premiers (Silver), and you could even have Global Services members who weren’t enrolled in United’s loyalty program. Now it’s integrated.
But you don’t have a goal to shoot for. They used to publish explicitly that you could renew Global Services status by flying 50,000 miles worth of full fare coach or paid premium cabin tickets, although you wouldn’t be guaranteed to initially qualify that way.
I always think secret criteria is a bad idea, it’s better to give members a stretch goal to reach for and let them respond to incentives.
United also must think that their review process is flawed, or makes mistakes, because they actually have a process to let you ask for the status.
The 2015 Global Services Reconsideration process will review members that believe their travel activity should qualify for Global Services status. Upon completion of the review, members will be notified by email on January 15th or within 10 days of enrollment which ever is later.
You just enter your MileagePlus number, and and then hear back in 10 days (but not earlier than January 15).