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It has three floors, a gym and there is always a doctor on board. But getting a ride on Air Force One can be tricky. Only 13 journalists are allowed to travel with the president when he flies, and this week the BBC's Jon Sopel managed to bag a seat on the plane.

As the BBC's North America editor, I travel all the time. From one regional airport to another on American airlines where the best you can hope for is a packet of pretzels.

Americans fly for work like Britons hop on and off buses or trains. Consequently it is utilitarian. Customer service is virtually non-existent. It is grin and bear it travel. Though more grim than grin.

Air Force One is not like that.

Before I describe the flight I need to explain the bubble and the pool.

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First the pool. This is the group of journalists who travel with the president - because space is so limited on the plane you're not working for your own news organisation, you're working for all news outlets. It is limited to 13 people; all material is shared and fed out simultaneously so no-one has a competitive advantage.

The bubble is the secure, hermetically sealed force field in which you operate. Inside the bubble you are called "clean". Outside you're "dirty". So on the day of the flight, we gather in the hotel where the president is staying. With our bags. A dog first sniffs them, then two secret service guys open every piece of luggage and sift through everything. Yes, dirty underwear and all.

You then go through metal detectors and board a bus. And we move in the presidential convoy. From now on we are inside the bubble. An armed secret service guy is assigned to us. He is called "the wrangler". Think sheepdog and sheep. We are his obedient flock. There is also a White House press officer who has to yell at various times, "Press pool, we're moving!" You are not allowed to leave the bubble at any point. Where the president goes, you go.

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At the end of a day of meetings with Gulf leaders, at which we've had a ringside view, we join the presidential motorcade that takes us to the military airfield, and arrive at the foot of the plane. No further security is needed - we are the "clean" pool inside the bubble.

The principle to moving about the aircraft is that everyone can wander around - but you can only move towards the back from the area where you are seated. The president sits at the front so he can go anywhere. He has a bedroom, a gym and a huge conference room. Then there are his key staff and senior officials. There are the communication teams at banks of encrypted computers so that the president is never out of contact, there is a medical station, his security detail, the secret service. And as you go further back, reaching the bottom of this ecological food chain, there's us!

I don't have a boarding pass or an assigned seat number but in the press section, I find my seat by way of a neatly printed invitation-style card, saying "BBC, welcome aboard Air Force One." It is perched on top of a comfy cushion with the presidential seal. The seats are way bigger than you'd find in the economy section of a normal jumbo, but they don't fold down into flat beds.

And then there's the vote. A vote on which film to watch on the two big screens. The American journalists go overwhelmingly for a James Bond movie.

Now I said we are nearly at the back. Behind us is the aft galley and it is a kitchen with a team of chefs who buy fresh ingredients to cook proper meals. There are ovens and a hob - not an aluminium foil container or trolley in sight. Christine, our head chef, is a fluent Arabic speaker and used to work in intelligence. But she wanted to see the world so joined the US Air Force. And now she's on Air Force One. Meals are served on the plane's crested bone china. Dinner is filet mignon, wedge salad and cheesecake, since you ask. The paper napkins have the presidential seal and the words "aboard the presidential aircraft". I'm amazed to find that, when later that night I get to my hotel, several of them must have fallen into my bag. Honestly officer.

But the prized swag are the little boxes of M&Ms exclusive to Air Force One, replete with presidential seal and a picture of Barack Obama. There used to be Air Force One playing cards and even cigarettes. I am also awarded a certificate, signed by the captain, saying that I was a guest of the president aboard Air Force One.

And when we land at Stansted Airport there's no immigration or anything tiresome like that. Instead there are three marine corps helicopters, plus Marine One for the president waiting to chopper us to the ambassador's residence in Regent's Park, next door to London Zoo. From touchdown to central London, maybe 25 minutes. I've always debated what's the best way back into town from Stansted after my less glamorous flights. Now I know.

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