Teaching someone to do something that you have never done yourself is difficult. While it is possible to teach someone the theories that they can apply in their own workplace, or to extrapolate experience from one field into a related area, trying to teach someone a skill that you have never used in practice is highly problematic.
One issue that can arise when a trainer attempts to teach skills that they have never used is that it can reduce trainees' confidence in their instructor. This is particularly true if a lack of experience causes the trainer to make any mistakes, however minor. A trainee who has more experience in a certain area than the trainer will quickly spot any basic errors, and once they have started to doubt their trainer's authority on the subject, they are less likely to listen or to take on board what they are being taught.
A good trainer should never attempt to teach something that they are unable to explain properly or to answer commonly asked questions about. Trainers should be able to identify common misunderstandings and problems, and know what is most relevant to the trainee's needs. Trainers also need to be able to teach by example, as this is the preferred and most effective route of learning for many trainees, which demands a certain amount of experience. The CIPD reports that 46% of trainees prefer to be shown how to do something and then given an opportunity to practice. Experience is a key part of the learning process, as envisioned in models such as Kolb's Learning Cycle, and if trainees are learning through experience, the trainer needs to have undergone the same process. In many cases, when experience is required, a small amount of practice can help the trainer to acquire it. For example, a trainer who is about to demonstrate how to use a new piece of software should be able to dedicate at least a couple of hours to exploring its various functions. In other situations, many years of experience may be necessary to master a skill well enough to teach it.
However, while it can be very important, experience alone cannot make a good trainer. The ability to teach well is just as important as having the right knowledge or experience, and effective teaching is something that needs to be learned and practiced. Teaching is an art that requires superb presentation and interpersonal skills together with the ability to recognise the different techniques that will work for different kinds of learners. Although experience can help a trainer to gain a deeper understanding of a particular skill or subject, it cannot substitute for the ability to build a rapport with students. In some situations, it can even be advantageous for an instructor to have less experience in the field their trainees know well. A trainer who has had different experiences than the people they are training can bring a fresh perspective that may prove valuable, just as the Harvard Business Review suggests that leaders coming from outside the field can often have a positive impact.
Some trainers do have a talent for 'winging it' and in some cases that is so well developed that attendees may not know that they are less than familiar with the subject matter. However, that can lead to overconfidence and the inevitability that one day it will bite them somewhere nasty.
Is it better to have an engaging trainer who is less familiar with the subject or a dull expert as a trainer? Now that would make an interesting discussion.