How did I get into this? I’m in the cockpit of a fighter jet flying over Sweden and the pilot has apparently handed the aircraft over to me. At Mach 1.2 – that’s 1,500kph. When Saab test pilot Hans Einerth calmly says “Your controls”, I assume he is joking. “You want me to grab the joystick?” Yes, he replies, so casually that he sounds more like a father urging his toddler to let go of the handrail and slip down a playground slide than a man relinquishing control of a $50m Gripen fighter jet.

I do as I am told and glance at the little circle in the corner of the display above my right thigh. We are indeed travelling faster than the speed of sound. Even so, I’m unfazed. I am, after all, merely holding a piece of plastic that is safely detached from the workings of the plane. Only when I follow Einerth’s direction to cautiously nudge the controls to my right do I realise this is not the case. I have just turned the Gripen on its axis and am moving us eastward towards Sweden’s maritime border with the Baltic states.

My exhilaration turns to fright when I notice Einerth fiddling with the GoPro camera whose suction disc is refusing to stick to the canopy. I can only grip the controls slightly more firmly and assume his ability to react to imminent disaster is measured in milliseconds.

The day had started early at Saab’s airfield in Linköping, southwest of Stockholm, with a change of clothes. It took almost an hour to get dressed for the ride – six times longer than the 10 minutes it takes the Gripen to fly the 150km from Linköping to reach its training area above the Baltic sea.

…

I put on green woollen long underwear and socks before being helped into a drysuit over which I slip on black leather combat boots. The combination should keep me from hypothermia were I to end up in the near-freezing seawater. But the heavy suit, designed to overcome high gravitational force, is ill-designed for standing, so for Einerth’s 20-minute safety briefing I gratefully manoeuvre myself into a chair.

Einerth had a long career in the Swedish air force before working for Saab, which makes the Gripen. Despite his credentials, it is disconcerting to be reminded that military aircraft are not held to the same rigorous safety standards as their commercial counterparts. “We’re a bit more relaxed from a safety perspective because we have an ejection seat,” he says, without a hint of irony.

As we walk on to the airfield, I realise why fighter pilots look so macho when striding towards their aircraft. I had assumed it was the affected walk of people who had watched Top Gun too many times. But there really is no other way to move in a G-suit, for the air cavities that run down each leg force the wearer to widen his – or her – gait. Add the helmet, whose oxygen mask makes carrying it anywhere other than wedged between hip and armpit almost impossible, and the Tom Cruise impersonation is complete.

The G-suit will help push my blood back up to my heart and brain when the gravitational forces become too great. Untrained passengers begin to black out at about 4.5G; pilots can handle more than double that force through training and breathing exercises that sound remarkably like the panting taught in prenatal classes.

Unlike childbirth, though, flying over southern Sweden’s landscape of quaint red barns and white churches is unexpectedly peaceful. Even at nearly 1,000kph, to which we have now slowed, the cockpit is perfectly still. But the calmness only makes me acutely aware of the piece of equipment that scares me the most.

Between my thighs is a black and yellow loop that was the focus of much of my safety briefing. If I pull it, my arms and legs will be pinned to my seat by metal loops; the thin seam of explosive along the canopy above me will shatter the acrylic and a small bomb will go off under my bottom. I will be propelled more than 60m into the air with enough pressure to crush my vertebrae, until my parachute unfolds and I descend either into the sea or, preferably, a field of surprised cows.

A fear of being overcome by an uncontrollable urge to pull that loop means I spend the first half of my hour-long flight with my fingers tightly clasping my legs. But Einerth, sitting in front of me, is thinking of a different kind of loop.

As the jet climbs vertically into the grey-blue sky he decides to execute a backward flip and I experience the least enjoyable part of my ride. My ill-fitting helmet feels like blunted screwdrivers being pushed into my head while the blood drains from my brain and – like curtains slowly closing – my peripheral vision darkens. My head is pinned to the seat, which would have been bearable had I kept my neck straight instead of glancing sideways at precisely the wrong moment.

We come out of the manoeuvre and I remind Einerth how interested I am in seeing what the Gripen does better than its competitors built by more powerful nations. The Gripen is the main defence tool of a small, neutral country that once lived in fear of Soviet invasion and still keeps a wary eye on its neighbour. So Saab had to be creative and thrifty. The aircraft had to be able to land in small places, Einerth had told me earlier. “They figured the main runways might be bombed, so we needed to be able to take off and land on damaged runways or highways.”

When we execute a backward flip, my ill-fitting helmet feels like blunted screwdrivers being pushed into my head

That said, “If you’re a nation with offensive ambitions and want to kick in the door on the first day of a major conflict, maybe you wouldn’t choose a Gripen,” he’d added. The jet is small and more visible to radar than stealthier US fighters. But that helps the Gripen attract interest from countries such as Brazil and Switzerland that do not want to be seen as aggressors.

For all my excitement about the fighter’s speed, it is its ability to fly slowly that sets it apart. Einerth demonstrates: we swoop down and buzz a tanker. “That’s strange – it’s anchored,” he exclaims. Usually tankers anchor far closer to shore, he says, making a note of the vessel’s name.

As we make our final descent, the runway storms into view and we come to an abrupt but graceful halt. I emerge from the cockpit waving two unused sick bags triumphantly, but hours later my body registers what I have put it through. I hallucinate all night, my legs feel heavy, my head and eyes ache and, for a week or so, my breath is shallow.

Only gradually, the old me emerges and the only signs that I steered a fighter jet while breaking the sound barrier are the Gripen Society membership pin on my lapel, and the slightly wider gait my husband insists I assumed when we boarded our holiday flight.

Slideshow photographs: Johan Fowelin

Carola Hoyos is the FT’s recruitment editor and its former defence correspondent