Designs » Failure by Design

Failure by Design

Suboptimal designs are introduced thereafter by the symbols, while corresponding proposals are on the next page.

 Faired Helmets

The only body protection with most light wings is a helmet. In cycling, you look usually ahead and this faired shape is logical. It is also common among hang glider and paraglider pilots, but as they turn their heads all the time to check clues, birds or other aircraft, the aerodynamics is more questionable. In an accident, any glider line or part may catch the tip behind your head and break your neck. But what a look!

Thermal Flying

Gliders (no engine) use the atmospheric energy provided by the sun as thermal updraughts to fly significant distances. To keep the atmospheric balance, if there are updraughts there needs to be downdraughts nearby, and the turbulences in between can affect the wing behaviour. The aircraft below have weaknesses, some give access to the skies to many also, nothing is simple. Choosing to fly with them, one should remain aware that they will not forgive much.

 Hang Gliders

Those aircraft weigh about 30 kg (or 40 kg with the whole stuff), fold into a 5 m long package, are ready to launch in 20-30 mn, cost roughly 11,000 US$ with all the equipment and can fly over 700 km.

Tumble: With its internal structure, the wing is usually only shaken by turbulence, causing some discomfort. Nevertheless, in very rough thermals or in some poor aerobatics attempt, the pilot may become weightless and lose control for a moment, or more rarely the wing may tumble, a continuous forward rotation around the pitch axis. It may break, mainly if the pilot falls into it, and then the only way out is the rescue parachute.

Forget to hook in: Here the pilot lies in a harness hooked in under the wing by a carabiner. It is advised to connect harness and wing before donning the harness, but depending on the launch configuration (abrasive ground, dust devils), that can be unconvenient or even hazardous. With harness and wing connected, only the leg loops must not be forgotten, if the carabiner is to be hooked in on launch, that must not be forgotten either.


Aircraft of that class are currently the most successful ones regarding practitioners, certainly for good reasons: they weigh around 10 kg ready to launch, fold into big backpacks, can be launched in 5 mn out of the bag while costing around 7000 US$ in 2020, and they fly sometimes over 500 km. Unbeatable!

Collapse: To be so light, no hard structure, the wing is a kind of mattress holding its shape thanks to the airflow, like the “rectangular” parachute from which it is derived. Sometimes in turbulence the wing deflates partially or completely until recovery after a few seconds. Pilots learn to deal with that in the training process, and throw their rescue parachute more often than in the rest of aviation, but in a big collapse close to the ground, only luck can help.

Forget to close leg loops: The pilot sits in a harness hanging below the wing. To get connected, the pilot dons the harness by the shoulder straps and must not forget to close the leg loops. “Unfortunately”, every “do not forget” involving humans means someone will forget some day. 100% sure.

Flatland Flying

In flat regions, any unpropelled aircraft needs to be towed aloft, by ground-based towing (winch, car or pay-out winch) for paragliders, or also by aerotowing for hang gliders (and sailplanes). A typical issue while towing is the evil lockout. Here are two hazardous release devices.

› 2-String Release

Copy of the skydiving cut-away device with thin rope strings instead of steel rings, this release is suited to aerotowing (low tension), but not to ground-towing: the line tension there is around the aircraft’s (pilot + wing) weight, and the mechanical advantage is between 16 (picture) and 4 in the worst case. In a lockout, you need to release immediately, but the release pin may be jammed by too much line tension.

› Velcro Limiter

Used long ago to introduce beginners to hang gliding in flatlands, the purpose of that tinkering is to prevent the wing nose to shoot up during the initial run, which would induce stall. It works perfectly as long as it is properly installed, but at least once, it was wrongly set up and eventually the tow line pulled on the wing nose.


In this sport, the proximity with hazard is obvious and safety has been taken seriously for a long time. Moreover, jumping is often practised on organized and dedicated airfields. Equipment checks are thus systematic and being in a group helps also checking each other in a more informal way.

› Chest strap

However, there is a little “do not forget” left: you must close your chest strap properly to be connected with your harness, passing the webbing twice in the buckle. Otherwise, in the worst case your shoulders may pass through the straps during the opening sequence of the main sail.

Cloud Flying

In aviation you fly either in visual meteorological conditions (VMC) or with instruments (IMC). Unless having dedicated instruments, it is strictly forbidden to fly in clouds. Risky too, not to say crazy. If you are already there, the aircraft of choice is a paraglider, provided the lines are taut. The lines’ height makes it very stable in roll, so you have chances to fly rather straight and hopefully soon out in the blue.

› Helicopters

Disorientation: Helicopters are perhaps the most sensitive aircraft in pitch and roll (statically stable but dynamically unstable: oscillations become stronger and stronger). You need to be 100% awake and oriented in space, and hold the stick all the time. Losing visual references, you get disoriented after a few seconds, a life-threatening condition. A wonderful machine that saves lives but clouds, smoke or haze are the last places you want to be.

“Extreme” Sports

For almost all their stay on this planet, humans were only able to dream of diving longer than a few minutes, climbing in high mountains or flying, and we are quite lucky that these exhilarating activities have become possible by the 20th century, even sometimes easily accessible and affordable. These environments are not those our bodies were intended for but some pioneers found ways through all challenges, and later on simple citizens could attend courses and learn in a quite controlled frame. However, our bodies had not enough time to adapt and the practice environments are still unnatural. And we never know how much luck we have left in our bucket…

› Plan A

A risk assessment is required at this point: Is there a reasonable chance of positive outcome? What could go wrong and can the issues be managed? Our ancestors did that before making boats and sailing across the oceans without any GPS. Is the plan A good enough, is there a plan B? It is well known today that staying over 7000 m with or without oxygen is possible for a limited time, that scubadiving alone, cave diving, base jumping (usually with only one parachute) and so on are dangerous.


Poor designs are also found in organizations. But at first let us experiment the NASA group test Lost on the Moon, during a seminar for instance. It is interesting to add the whole class or seminar as 3rd round after the individuals and (4-5 persons) teams. The pedagogical fun comes sorting out who came closest to the NASA template. The class wins, the teams come 2nd and the members last: a group is more clever than its members. Wow!

› “Inbreeding”

But if the members have too close backgrounds (sex, age, origin, education, profession), the difference between group and individual thinking is likely to be lesser. In an unforeseen event, that homogeneous group may miss the one who could realize they are taking a wrong path. In the real world, people often knew someone in the organization before they came in. So selecting persons with similar profiles (artists, engineers, lawyers…) in a group is a rather “natural” trend and organizations may easily fall in this trap.