100 Maiden Flights – by AP Kotze

I started gliding in 2004 at Potchefstroom gliding club after attending a training day during the final year of High school. Being from a small town, approximately 50 km north of Potchefstroom, and being involved in farming activities during most of my time there my original plan was to become a veterinarian. One flight in a glider however convinced me that I might be better off pursuing a career in engineering.

First Solo Flight

By chance I also met Johan Bosman and Uys Jonker when Jonker Sailplanes was just starting up. The facility was still based on the North West University grounds. I realised afterwards that I was actually witnessing the cutting of the first wing moulds but did not even know what Johan, Uys and Attie was planning.


My training was completed on K7’s and SF25 mostly under the experienced eye of  Tienie Jonker, Uys and Attie’s father. It took 32 flights to make it to solo and lots of frustrating hours after that to actually realise what gliding was about.

Jaco Burger and I flying 330 km in a K7


Fast forwarding to 2009, Jaco Burger and I competed in our first Regional contest in Welkom in the Free State with some financial assistance from senior members at our club. It was the coldest camping experience of my life with temperatures reaching well below 0 degrees every evening. It was probably around this time that I starting realising that gliding for me will always involve flying competition. Merely floating around in a glider was just not interesting to me at all. We had the use of the club’s Club Astir which we shared (one pilot flying and one pilot crewing) and had to endure a lot of comments about our wheel hanging out on task.


Later that year I started flying Uys’s Standard (Non-standard) Cirrus and used this to compete in my first national contest also held at Welkom. The contest was highlighted by very large storms almost every day and also with Oscar Goudriaan’s, the task setter, frustration with the club class. Competitors of the club class insisted in flying to the very edge of every assigned area circle that Oscar put on the task sheet, and then subsequently landed out, resulting in having to be fetched by the Open Class pilots as crew was scarce. One morning the entire club class was asked to stay after briefing for an AAT training session. After this the amount of outlandings became less but not by much.

Club Class Nationals 2010


I attended my first World gliding championship in Szeged as crew in 2010. It was very different from a club class contest in the Free State! It was also during this time that Uys asked if I would be willing to get involved in the the Jet Sustainer project. The thought of it was interesting to me and as I was already working part time at the factory it seemed like a good project to get involved with.


During 2010 and 2011 the Jonker Sailplanes/Soaring Safaris Challenge 2010 was held. The aim of the contest was to give incentive to inexperienced pilots to fly cross countries during the year. The 3 best OLC flights would then be used to determine the winner. The price for the contest was a weeks’ worth of flying at Soaring Safaris in Bloemfontein with Dick Bradley sponsoring the glider and Jonker Sailplanes sponsoring the aero tows. This was a great opportunity for  young pilots to receive some proper cross country training in very good weather. I was fortunate enough to finish on top in 2011 and fly Dick’s Ventus around for a week. I also completed my first 500km flight during this week.


In 2012 I attended the WGC in Uvalde Texas (best contest that we have ever been to by far!!!). Uys mentioned that I would be allowed an opportunity to fly a JS1 once I’ve reached 450 hrs of total time – challenge accepted!! When we arrived back in Potchefstroom I flew a lot and with 450 hrs and 2 min I walked into Uys’s office and reminded him of the deal he had made. It took a little bit of convincing but in December of that year I had a 1h30m in a JS 1B (#23). It was a step up from the Std Cirrus and a definite highlight. In January 2013 I drove to the airport to pick up something before going away for the rest of the weekend. There was a lot of activity at the airfield and apparently the weather was going to be extremely good that day. Uys asked if I would like to join them for a 1000 km attempt. At my experience level this sounded like flying to the moon but I joined in, loading the JS1 full of water for the first time (this was to be my second flight in a JS1). I have to admit that I was not setting the pace during the flight. Oscar and Uys spent hours on the radio telling me what to do (trying to get me to catch up) and turned short at the first and second turn point in order to maintain contact with them. Thinking back I am certain that their biggest motivation was to not have me land out 400 km from home and having to make the retrieve. We ended up outlanding at Klerksdorp (50 km west of Potchefstroom) as a result of a thunderstorm in the late afternoon. To my surprise when we uploaded the traces that evening I had completed my first 1000km flight (although not declared). Definitely another highlight.

Uvalde 2012

I did the first maiden flight of a glider in 2014. Serial number JS1C-061 was the aircraft being tested. 2014 was a busy year. We had to assist in some of the certification testing of the TJ42 engine. the specification was to run the engine at -15 deg C for 3 hours. Even during winter we do not get temperatures this low in Potchefstroom so the temperature test turned into a flight test searching for required temperature on the way up. The jet system in the JS1 carries 42 L of fuel and even with increased altitude and the reduced fuel burn we could not get the required endurance out of the system. The flights were therefore conducted with approximately 160 L of diesel in the wing tanks, more than enough fuel to complete the test. We did achieve the desired temperature but only at 23 000 ft, a long climb with such a small engine and such a heavy glider.


During 2015 we started certification of the JS1 C in Europe. This was my first experience with testing of aircraft with the intention of showing compliance to CS-22. I think that the effort that the manufacturers go through to ensure that their products are safe and meets the specification is not always appreciated by the clients who end up flying them. Jonker Sailplanes has attempted to close this gap by uploading multiple videos to Facebook and Youtube in order to give clients a view from the cockpit during these tests. From a technical side it is extremely interesting to watch and may give a clearer picture of what the gliders are capable of and where the edges of the envelope are in these modern gliders.

AP flying JS1-C

One flight that I do remember quite well is the maiden flight of JS1C 114. On the day the clouds was low for a summer day in South Africa and quite close together which made for spectacular scenery. The link to the video can be found on Facebook:

JS1C-114 on its first flight out of Potchefstroom. Awesome flight.

Posted by AP Kotze on Wednesday, 16 November 2016


The biggest highlight was competing in the WGC in Hosin during 2018. At last I got to experience what it was like in the cockpit of the glider and not crewing. It ended up being an amazing contest that was extremely well organised, especially the weather!! Gaggle flying is demanding and flying contests over such a long period requires proper preparation and lots of training and experience. The pilots who end up at the top of the field during these competitions are a breed apart from the rest and deserve a lot of respect!

Zoran Frenc, AP and Uys at WGC 2018

All of these experiences has lead me to a day in 2019 when I took a glider on its first flight for the 100th time. I could not believe that the number had come up and had to verify that this was correct by going through by logbook a number of times. The increased production rate that Jonker Sailplanes has achieved over the last number of years has made this possible and as the production rate increase after every year I am certain that number 200 is not that far away!!