If you don't brief them at all, is not a leson anymore, it's a pleasure flight, and for that you need an AOC, that is why it would be ilegal.
LEVC Can you quote the proven test case for the above, if not what you meant to say was in your opinion it would be illegal.
how do you define briefing--can you quote the ANO section you would use in court-- a pre-flight briefing is an explanation of what is going to take place during flight-there is nothing to stop that briefing being given in the club, in the toilet, on the way to the aircraft at or in the aircraft. it could be argued that its not best practice but poor practice is not illegal(unfortunately) If i say here is the C152 we are going to start up, taxy to runway 27 take off fly to the west and return and land thats a pre-flight briefing maybe not the best but it tells the student what we are going to do.
In the same way if someone got on my aircraft at heathrow who was taking flying lessons(pre 9-11) and i gave them verbal instruction would it be illegal because my instructor rating is not valid. eg i am giving instruction on a public transport flight without a valid instructors rating
In my opinion intent has to be proved. If you intend to take someone on a pleasure flight and they intend to go on a pleasure flight and it can be prooved it could be construed as a public transport flight.
If someone comes along with the intention of having the experience of a flying lesson even knowing they are never going to have another one in my opinion the does not make it a public transport flight.Its when they come along and ask you for a pleasure flight that intention changes.
A sensible flying school will have several measures in place to help prevent any misunderstanding eg membeship with conditions, pilot order books which technically a student should look at before flight and a disclaimer form spelling out the conditions of the trial flight.
As instructors you need to be more concerned about what could happen if an accident occured in your genuine trial flight-- have you covered all the possibles--ever wondered why it says MOTOR RACING IS DANGEROUS at circuits? make sure your disclaimer form spells it all out for the criminal injury lawyers because you will find they are smarter then you are!