André Borschberg’s top 15 moments with Solar Impulse

My last Round-The-World flight with Si2 has come quickly and so I decided to share my 15 most intense moments since the adventure began.

It all started when I heard about Bertrand’s idea. I was thrilled and knew it was the moment for me to accomplish my dream: combining my entrepreneurial experience, and my passions for innovation and aviation pioneers.

That day in Dübendorf, Switzerland, an innovative and pioneering vision finally became a reality. Solar Impulse 1, designed to fly both day and night, was inaugurated and the 800 people present at this historical event were not disappointed. It had taken us seven years of hard work, a lot of focus and energy, and I couldn’t wait for the test flights to begin!

Demonstrating what we had been aiming for for 8 years was an incredible 24-hour long moment. What suspense! What intense concentration! Flying without fuel sparked a fantastic feeling of freedom within me. From inside Si1’s cockpit, I was well aware of the physical strain of staying awake for more than 24 hours. In addition to the challenges of managing the ultra-light aircraft through gusts of alpine winds, my water source froze when I reached high altitude, and I could feel that the team was tense. But to everyone’s delight, I landed on the Payerne airfield 26 hours and 10 minutes after takeoff, thus proving possible what had been ruled-out as impossible by many: flying day and night with a solar airplane! This historic moment resulted in three world records in the “Solar-Powered Aeroplane” category: “Gain of Height” (8744m), “Duration” (26h 10min 19s) and “Absolute Altitude” (9235m).

It was Si1’s first time abroad - crossing boundaries, flying over different landscapes and clouds with only solar energy - and its first step towards long endurance flight. only After 12 hours 59 minutes of flight and 480 kilometres, I landed the plane in Zaventem airport where we received a triumphal welcome. A smooth landing but not the easiest of flights. I was supposed to land at 9pm, but because the wind veered, there were several changes of plan and the landing had to be delayed for half an hour. It was nevertheless fantastic and when I arrived, the batteries were full. If they’d had a bigger capacity, I could have fed electricity into the grid after landing… For me it was the most powerful message of this flight, apart from coming to a great European capital.

Ouarzazate, the middle of the desert! It was the Crossing Frontiers mission and I was not sure the desert would accept Si1. Strong night winds can sometimes arrive very suddenly and disappear in an instant. Would I encounter these winds and turbulences during my flight from Rabat? I decided to spend a full night on the airport, outside, sitting next to the runway, just to feel the sky and the environment, for us to get to know each other. The sky was full of stars, the night was gorgeous, and I felt that I would be welcomed there with Si1. But it took me more than one trial. The first time, the winds over the Atlas were stronger than expected and, at 9000 meters high, I was suddenly no longer moving forward, unable to reach the other side to land in Ouarzazate. So I had to go back to Rabat and try again. The second time I was sick, but decided to go nevertheless. But I got so cold at 9000 meters over the Atlas that I decided to accelerate my descend, thus killing all my energy reserves. It was impossible to do otherwise. Luckily, when I reached the other side of the Atlas, over the desert, everything started to improve again and I could finally land safely in Ouarzazate. What an experience!

As the engineers in Dübendorf, Switzerland, were performing load tests on Si2’s spar - the main structural part of the wing, similar to the backbone of the human body -, it literally exploded! It was a huge shock for the entire team. This was going to cost us at least a year of financing, assuming that the team could quickly assess the reasons of the failure. The entire project was at risk financially, technologically and psychologically as our level of confidence was shaken up. But this was a transformative moment for me, when I moved from explorer to leader: instead of thinking that we lost a year to rebuild the failed part, I began to say we had gained a year. Suddenly we had one more year available until we could start the flight around the world. I decided to bring our first airplane Solar Impulse 1 to America to fly from coast to coast starting in California. Something Bertrand and I had always wanted to do but didn’t know how!

I’ve always been the helicopter pilot for the Solar Impulse aerial pictures. The first time was over the Matterhorn in Switzerland and this one was iconic. It was incredible to see Bertrand fly over the Golden Gate bridge, this landmark of the United States. I was piloting the helicopter carrying our photographer and cameraman, hanging out of the open door and playing with lenses, angles, and light to get the best shots of Si1. The photoshoot was almost cancelled due to high winds and the arrival of fog, but in the end it worked out and we got some of the best images ever of the plane.

This flight from Phoenix to Dallas was the longest distance flight in the history of the project, making it a unique but challenging journey. The pre-flight preparations were intense because of the specific wind conditions. The lightness and slow speed of Si1 allowed me to live a true “sky surfing” experience, literally riding the updraft and downdraft of the mountain winds. It was also a perfect training experience for both I and the Mission Control Center as it reminded us of the need to be flexible and keep different options at hand.

That day, I was flying Solar Impulse 1 from Washington DC to New York, the last leg of the Across America mission. At midday, while I was over the ocean, a media helicopter came close to take some pictures, and immediately told me I was loosing part of the wing’s undercover. He took some pictures, which he sent to our Mission Control Center. The first feedback I got from my engineers was that they were astonished that the wing did not disintegrate yet! You can imagine the shock I felt at the moment. At once, I started to prepare for bail out and went through all the steps I had to do before landing in the water with my parachute. I felt that I should be able to do it with the training I had done, and so I told myself: “You don’t get the chance to bail out every day over the Atlantic Ocean, so if it happens, you better enjoy it!” It would be another life experience! This perspective completely relaxed me, as I knew I could handle the worse situation in a safe way. From that moment I was able to stay focused and calm during the 9 remaining hours before safely landing in JFK airport. It was the first time a solar powered airplane had crossed the USA!

To undertake the Round-The-World adventure, we had to make sure that both the plane and pilots would be endurant. Which is why in 2013, Bertrand went through a 72-hour simulation of the crossing of the Atlantic from America to Europe. Having gone through this exercise myself in 2012, I knew how important it was for pilot to learn how to best live in the cockpit - learning how to manage one’s own energy, to develop one’s eating habits and understand one’s bodily functions. As I wished Bertrand a safe “flight”, I was sure he’d have a wonderful time and enjoy this amazing experience in exploring and discovering oneself.

This day will live long in my memory. After spending more than three years organizing, thinking, and supervising our engineering team as they built Si2, I was able to fly it for the first time. When I observed the progress made since the first main-spar fractured during a load test in 2012, I was full of admiration for the energy displayed by the entire team: the Across America mission in 2013 with Si1, assembling Si2, presenting it in April, its first flight in June, and so much more to come!

What Bertrand and I felt that day was a mix of childish excitement and sense of responsibility. For 12 years, with our fantastic team, we’d simulated, calculated and imagined but nothing could compare to testing and doing it in real. After taking off from Abu Dhabi I was lucky enough to be able to fly over the breathtaking Sheikh Zayed Mosque, the largest mosque in the country, followed by the magnificent northern Al Hajar mountains. This flight was both the “test flight” of the Round-The-World, but also a symbolic one as it was the one kicking off this fantastic adventure. It’s funny to say but as I landed in Oman I was already starting to feel at home in Si2’s cockpit.

The 5-day-and-night flight over the Pacific, from Japan to Hawaii, was the longest and most difficult leg of the Round-The-World. Both for the engineers who had been working to achieve this goal: a success would mean they’d have done their job properly, but a failure…? And for the pilot: each day I climbed the equivalent altitude of Mount Everest, without much rest, and had to pilot Si2 with the help of the Monaco Mission Control Center. So everybody was extremely tense, especially after having waited for two months to find the right weather window. It was also the first oceanic crossing accomplished by a solar airplane, so you can imagine how exhilarated I felt when I landed in Hawaii. It validated the vision Bertrand had after his round-the-world balloon flight to reach unlimited endurance in an airplane without fuel. And we broke four world records: that of distance along a course, straight distance, and duration for solar aviation, as well as that of longest solo flight ever.

This flight from Lehigh Valley to New York stood out from the rest of the Round-The-World flights. First because it was very short, second because it marked the end of the crossing of the USA, but more importantly because it included a flyover of the Statue of Liberty. Something I had not been able to do in 2013 because we had encountered technical problems with Si1. I had thus been waiting for years to be able to fly over this symbol of American values: the liberty to be a pioneer, the freedom to explore and invent. It also welcomes travellers who arrive in this country, and flying over it was a tribute we paid for the special welcome we received in all our American destinations.