The secret, ultra-elite airline status that informs you of delays before the captain knows and seamlessly transfers you onto rival airlines... and how you can get it

Frequent fliers across America's three biggest airlines have taken to social media to boast about upgrades, endless glasses of champagne and even a private car service across the tarmac, right to the foot of plane.

A battle for overhead bin space is a thing of the past, as those with such elusive status are the very first on the plane. 

Upgrades are common, with economy tickets transformed into first five days before the flight - before anyone else.

Those whose plans are disrupted by bad weather or cancelled needn't worry with re-bookings made without a single call being made. For those that want to speak to a human, a 24/7 dedicated phone line is also available. 

It might sound like the life of a VIP or celebrity, but such perks can be earned, but only by invitation to semi-secret airlines statuses, that sit even above the highest tiers of the airline's own loyalty program. 

American Airlines has Concierge Key, United Airlines offers Global Services while Delta's invitation-only status is known as Delta 360°.

There is an elusive level of frequent flier status but you'll have to spend at least $50,000 a year

Tarmac transfers can be yours if you have a tight connection and have been invited to become Concierge Key

Just what the requirements are to attain such levels of airline passenger superiority are a closely guarded secret with variables and metrics that shift from year to year.

Similarly, just how many members exist with such coveted status has also never been revealed by any of the 'big three' carriers in the United States - but it's believed to number around 10,000.

American Airlines' invitation-only elite status level Concierge Key has no set published criteria in order to earn it - but it's believed spending $50,000 on airline flights is one of the key metrics used to secure an invite.

Concierge Key can also be earned if you have influence over how other's travel such as part of a big corporate contract, or are a travel planner. 

The airline has been known to give away Concierge Key to some 'influencers' - but it is renewed on a yearly basis. Don't fly enough, and you don't get it the following year.

The benefits allow for the highest level of upgrade above all other frequent fliers from five days before the flight takes place. 

Access to the Admirals Club and exclusive Flagship Lounges are a given - even when traveling domestically within the United States.

Perhaps best of all, there's no waiting around for customer service with a dedicated phone line and email address for 24/7 support. 

Those who join the semi-secret level are given a flash metal bag tag to make others envious 

Flagship lounge access with a premium drinks selection is a given for those who are members

The airline does it's best to make sure those with the Concierge Key level make their flights 

It's a side to the airlines many regular fliers neither get to see nor experience 

Although unpublished, it's widely believed that those who are invited to the exclusive status spent at least $50,000 with the airline

And travelers will never have to worry about a lack of overhead bin space with another perk being allowed to board the aircraft before everyone else. 

On a day when flights are being canceled and delayed left, right and center, those with Concierge Key may be rebooked proactively without having to make a single call. 

The airline also has a fleet of waiting cars for transfers on the tarmac for those with tight connections. 

It's quite possible you might be collected from the plane and whisked to your next flight in an airline-branded car.

'That's the stuff that makes the difference,' one frequent traveler with the elusive status explained. 

'That's the s*** that gets you home. They don't hold the plane, but if they know you're coming, they might not shut the door as quickly.' 

Scott Chandler of American said that in order to be in with a chance of scoring an invite, fliers might be spending on flights, shopping portals and airline-branded credit cards. 

'They're basically interacting with American on a daily basis, not just when they're flying,' Chandler explained. 

United Global Services have a special check-in area for such travelers 

A special reception area awaits those who manage to attain the sought-after status

The benefits are also conferred on those traveling on the same booking as the member

Global Services is United Airlines' invitation-only elite status. But unlike Concierge Key, the one direct way to earn it is to have flown 4 million miles on United. 

This is likely decades of flying, so for those looking for something sooner, fliers have to be able to tick the boxes of the secret criteria. 

Again, what these are is known only to those who work for the airline at the highest echelons, but for those who do earn it, they experience a service that goes above and beyond. 

United Airlines' biggest spenders are often invited to Global Services with a spend of at least $50,000 a year. 

The status can also be handed out by the airline to travel influences including those in the corporate world. 

Celebrities and VIPs have been known to receive it to ensure they receive the very best service when traveling with the airline.

The perks include the highest upgrade priority for United flights five days before departure. Members are also given the highest priority for standby and sold out flights. 

'I mean I fly first class 95% of the time - I am proud to be one of the Elite United Global Services Members - there is only 2000 of us in the world out of 100 million + I LOVE UNITED! It’s invitation only', wrote one TikToker. 

United has a snazzy SUV to shuttle passengers with tight connections between flights

You'll get to board before everyone else meaning there'll never be a battle for the overhead bin 

There are special Global Services check-in facilities at United's main hubs such as Denver, Newark, Houston and San Francisco.

For those tight on time, a Mercedes will take travelers from one gate to another - across the tarmac.

While a dedicated 24/7 hotline and email address exists for those looking for personal assistance. 

Bonnie Crawford is the chief customer officer for a software company in Portland, Oregon and after her United flight was cancelled, because she was a Global Services member she was rebooked on an Air Canada flight for free. 

Crawford first received the status in 2017. 'It was the first taste of this magic, elusive, absolutely incredible status,' she told WSJ.com. 

Passengers that need to make a connecting flight will be met personally by airline staff

Delta has a Porsche to transfer passengers across the tarmac when they have a flight to catch 

Delta also offers a private check-in area for those who attain this elusive status 

Delta Airlines describes the status on it's own website but the perks and requirements for membership are particularly vague. 

It reads: 'Delta 360° is an annual, invitation-only membership for our most loyal SkyMiles Members. 

'A Delta 360° Membership offers Delta's most premium suite of benefits and services exclusive to our top SkyMiles Members.'

Those being awarded the status are generally those who already book full fare tickets including those in first and business class.  

Those who are able to influence the travel of others are also believed to have a good chance of securing the status such as being in charge of major corporate travel contracts for a company.

Specially designed Delta 360° bag tags which can sell on eBay for hundreds of dollars

Some have suggested travelers would have to spend $100,000 per year on Delta flights to be invited as a Delta 360° member.

The benefits include a dedicated 24/7 phone line with immediate assistance. Access to the Delta Sky Club for family members which would normally cost $1,500 a year.

Delta also offers its members transfers across the tarmac in a Porsche SUV during short connection times. 

And of course, specially designed Delta 360° bag tags which can sell on eBay for hundreds of dollars.