Oscar Munoz is “upset” about what happened on United Express flight 3411. The United Continental chief executive “deeply regrets this situation arose”. Well, of course he is and of course he does. The video of a screaming and bloodied passenger being dragged forcibly off the overbooked flight from Chicago to Louisville is upsetting, and the “situation” was highly regrettable.

At first glance, it seems the path of least resistance would have been for Mr Munoz to issue a full and complete apology. I struggle, after all, to think of a case where saying sorry to a customer ever got a chief executive into more trouble than delaying doing so. But it is not quite as simple as that.

Airlines should be expert at the apology business simply because they have so much to apologise for. Lost luggage, missed connections, cancellations, poor food, inadequate legroom. When disappointment or pain is inflicted on demanding, stressed and often jet-lagged customers sitting at deoxygenated close quarters, there is bound to be a backlash.