The jailing of a teacher for manslaughter, after a 10-year-old boy drowned on a school trip, could make teachers less likely to take their own classes on out-of-school visits.
John Dunford says the jail sentence could put off teachers from taking charge of school trips
Paul Ellis, who had been a teacher at Fleetwood High School in Lancashire, pleaded guilty and was jailed for 12 months, following the death of Max Palmer on a school trip to the Lake District.
Teachers and head teachers' unions said that they were not aware of any previous jail sentence for teachers in such circumstances - and there were concerns that staff would no longer want to risk taking charge of school trips.
Head teachers' leader, John Dunford, said that this had been a terrible tragedy for the boy's family, but that there would also be the feeling that the jail penalty for the teacher was "disproportionate".
"School trips add so much to the experience of school - but there will be some teachers who will now be put off from taking pupils," said Mr Dunford, general secretary of the Secondary Heads Association.
Mr Dunford said that there was now a much greater awareness of safety - and much greater preparation before visits - but he still feared that teachers might no longer want to be responsible for school trips.
"Courts should take into account that teachers have volunteered to take such trips, and to give pupils extra opportunities."
The National Association of Schoolmasters Union of Women Teachers repeated its existing warning that teachers should consider refusing to take pupils on trips.
The National Association of Head Teachers advised teachers to continue taking pupils on school trips - but to ensure that improved safety procedures were carefully followed.
"My message to them is, stick with school trips, give pupils the experience
that so many of them need from outdoor activities," said general secretary, David Hart.
"Nobody is going to accuse them of negligence or even worse if they follow the guidance to the letter and don't put pupils in dangerous situations which lead to death or serious injury."
The Health and Safety Executive said that the jailing should not put off teachers from taking charge of school trips.
"HSE would not want to see school trips stopped, or teachers refuse to lead
them, as a result of this prosecution," said head of operations, Janet Wilson.
"But it is essential that they are planned properly and carried out safely. We know that most teachers put the safety of their pupils at the top of their agenda, and follow good practice."