The union also reminds us that teachers have shouldered the blame in recent high-profile cases. Some have lost their jobs and one is serving a prison sentence for manslaughter. The Department for Education and Skills in England has responded by asking teachers not to abandon visits because of their educational value.
Both views are right. A union has to protect its members' interests and nowadays, when an unthinking action or word - or worse, a vindictive pupil - can bring down any of us, we are grateful for its support. Yet thousands of teachers continue to take part in educational visits for the reasons quoted by the DfES. They know that a well-conducted visit, lasting a morning or a week, enhances pupils' learning and develops their relationships with one another and with the accompanying adults. The benefits are taken back into school.
However, today the world is not run by accountants only. The lawyers have joined in, bringing risk assessments and other paperwork in their wake.
Those of us with long experience of educational visits at home and abroad were assessing risks before the term was invented. In the name of good organisation, we explored our destination in advance, settled on the best and safest routes, checked out the transport operators and counted heads in our sleep. Now, to protect our backs, we lay down a time-consuming paper trail. At least it provides protection and allows teachers to continue with school outings, if they wish. But it's not just union advice and the fear of litigation that threaten the future of school visits. There are other problems more likely to strike, especially on overnight expeditions.
Government departments and education authorities may extol the value of educational visits but their words are easy. The reality is that most are led by enthusiastic individuals who undertake the financial and practical organisation on their own and in their own time. The burden is already too great to be carried by one person's goodwill and schools and authorities need to encourage a team approach with a commitment of professional time and resources. Easy words have to be replaced by "what can we do to help?"
One way would be to provide time off in lieu or some other appropriate consideration for teachers staffing an overnight outing. Their work is voluntary and their commitment substantial. They have 24-hour responsibility and are the antithesis of the clock-watching teacher.
Nevertheless, we cannot assume such continuing selflessness without fitting recognition.
Even that will not solve the gender problem. The requirement that a teacher of either sex should accompany a mixed group of pupils provides a serious obstacle for primary schools. Few have a male teacher, let alone one prepared to give his time to an overnight visit.
Even if there is a male parent with the requisite skills of group communication, his working hours are unlikely to be favourable. So what's wrong with all-female staffing for a visit? Many 11 and 12-year-old boys live with a single, female parent all year round.
Then there is the question of inclusion and the extent to which it overrides the rights of others. Once it was only the inability of a child's parents to pay that needed to be resolved. Now a risk assessment may reject the child who cannot be trusted to behave normally. The risk to the party's safety, not finance, will exclude some children from the visit.
If our leaders really believe that educational outings are valuable, they must provide the practical help that is needed to ensure their survival.
Brian Toner is headteacher of St John's primary in Perth.