Those who are already nervous about flying now face a further peril.
A couple of weeks ago, an attendant on an American Airlines flight between Dallas and North Carolina was reaching for a passenger’s sick bag when he was bitten on his left hand by the passenger’s dog. The attendant’s bleeding hand required five stitches.
In news reports, the assailant was described as "an emotional support dog". At first, I took this to mean that the support dog had become emotional.
But I had picked up the wrong end of the stick. By "emotional support dog", the reporter meant that the dog was employed to provide emotional support.
It emerged that American Airlines has recently tightened up its regulations on the range of animals it will allow on board for "emotional support". To accompany those passengers of a nervous disposition, it now says it will permit only "a cat, a dog, or a miniature horse".
A miniature horse? How could an already tense and highly strung passenger ever imagine that having a miniature horse with him might encourage him to calm down?
And what of the passenger in the aisle seat? I am a fairly relaxed traveller, but, if I were on an aeroplane and, glancing to my left, noticed a miniature horse leafing through the in-flight magazine, or repositioning his overhead light, or pressing his hoof on the little armrest button to make his seat go back, then I would start to grow very jittery indeed.
Obviously, I would do my best to stay calm, but, at the same time, I would be obliged to take a few precautions. I would certainly take care not to order any carrot-based meal and, when it came to selecting an in-flight movie, I would avoid all Westerns and anything else in which large groups of horses were likely to come to a sorry end.
Reports suggest that more and more people have been attempting to bring animals with them on flights, on the grounds that they need them for "emotional support".
Some of these animals are, in the words of industry group Airlines UK, "wholly inappropriate". In the US, they have included a peacock, a squirrel, a monkey, a pig, a duck, a turkey and a kangaroo.
Given the choice, which of these would make the most agreeable companion? Personally, I wouldn’t want a kangaroo sitting next to me, particularly on a long-haul flight, as he would be up and down, up and down, all the way.
At the same time, a squirrel would be too twitchy and, the moment you looked the other way, would attempt to steal your nuts.
At first sight, a peacock might seem an ideal neighbour: not too big and not too small, beautifully blue and with an alert, can-do air about him. But he is also very vain: just as you were settling down for a snooze, he would fan his feathers at you. While all your fellow passengers oohed and ahhed, you would have to suffer all those quills in your face.
For all their many virtues, monkeys are too fidgety and full of beans to stay still during a flight. Far from providing emotional support, they would parade up and down the gangway like drunks on a stag weekend, shouting ribald slogans and dropping their trousers to show their bottoms. And, frankly, I wouldn’t put it above a monkey to forget all about any duty of emotional support in favour of scuttling down the aisle to induct another monkey carer into the Mile High Club.
A turkey would, I think, be a little crotchety, especially if you tried to make small talk (‘Doing anything nice for Christmas?’). And a pig in the next-door seat might present problems. Pigs can be very single-minded, almost to the point of selfishness. Plus they spread themselves out: the moment you leaned forward, he or she would try to hog the armrest.
So there is clearly only one option: the duck. Personally, I think a duck - easy-going, reassuring, self-contained and spotlessly clean - would make the ideal travelling companion and emotional support.