In this post, John-Paul Swoboda provides his commentary on the recent decision in Arthern v Ryanair DAC [2023] EWHC 46 (KC).

When a person slips on some liquid on a floor, whether it be by a poolside, on an aeroplane, or elsewhere we call it is an accident. A slip is, by definition, unexpected. A slide may be intentional, but a slip cannot be.

If like me, you consider the above uncontroversial propositions you may find it surprising that in Arthern v Ryanair DAC the appeal court found a slip on liquid in a plane was not an accident.

The Montreal Convention, which applied to the facts of this case, states at article 17(1)

The carrier is liable for damage sustained in case of death or bodily injury of a passenger upon condition only that the accident which caused the death or injury took place on board the aircraft or in the course of any of the operations of embarking or disembarking.” (my emphasis added)

This issue in Arthern was whether a slip caused by liquid, found to be a mixture of water and de-icer, tracked into the cabin of the plane by passengers upon embarkation was an accident. The slip did not occur during the process of embarkation but later when the claimant sought to use a toilet. The amount of liquid on the floor was sufficient to wet the claimant’s clothes and the amount of water on the floor was said to be large. The finding of the judge at first instance on this issue was:

“…it is not in the scheme of things unusual or unexpected in cold weather for aeroplanes to have to be de-iced before travel, and so it is not unusual or unexpected for there to be de-icing fluid present on the tarmac and, from there, tracked into the cabin in exactly the same way that water can be tracked into the cabin. In my judgment the objective passenger would not view this as unusual or unexpected for the same reasons as I do not find it unusual or unexpected.”


“… The fact that the Claimant says there was quite a lot of [liquid] does not seem to me to make a difference …”

The judge was surely right to say that tracking of some moisture into the cabin on a rainy day when passengers embark by walking to and up external stairs to the aircraft is not unexpected, but wrong to say it is not unusual. By definition, if as the judge on appeal stated, it only happens on a tiny minority of days, it is unusual. The judge, in my view, was also surely wrong to say the volume of liquid does not make a difference.

Mrs Justice Farbey in dismissing the appeal found the judge applied the correct legal principles and therefore the decision was unimpeachable. Farbey J found that the assessment of the judge below as to whether the event was an accident was not one which could be interfered with by an appeal judge.

What are the legal principles to be applied? This is an issue which despite being deceptively simple (i.e. is it an accident) has given rise to an abundance of case law. I cannot hope to do justice to all the case law in this blog but given the parties and the Farbey J placed weight of the distillation of principles in Air France v Saks 470 US 392 (a decision of the US Court of Appeals for the Ninth Circuit) and Carmel Labbadia v Alitalia [2019] EWHC 2103, so will I.

In the Air France case the claimant suffered hearing loss when a plane landed, but aircraft pressurisation system operated correctly and there was nothing unusual about the landing. The claim failed. For an event to be an accident, it was decided, the injury must be caused by “an unexplained or unusual event or happening that is external to the passenger. This definition should be flexibly applied after assessment of all the circumstances surrounding a passenger’s injuries”. O’Connor J in Saks also observed a passenger need establish only that “some link in the chain was an unusual or unexpected event” for the event to be an accident.

In Labbadia the claimant slipped down aircraft steps when disembarking in Milan in snowy conditions. The claim succeeded. Margaret Obi J distilled that the following were necessary ingredients for an accident within the meaning of the Montreal Convention:

“… if there has been an ‘accident’ requires consideration of whether there has been an injury (i) caused by an event; (ii) that is external to the claimant, and (iii) which was unusual, unexpected or untoward rather than resulting from the normal operation of the aircraft.

Do these considerations change the slip in this case from what in normal parlance is an ‘accident’ into a mere event when looked at through the lens of the Montreal Convention? If we take the distillation of principle by Margaret Obi J first: there was injury caused by an event, a slip; the slip was external to the claimant as it would not have occurred but for the presence of the lubricant on the floor. But was the presence of water and de-icer of sufficient quantity to wet the claimant’s clothes, during the flight (after embarkation) unusual, unexpected or untoward? Or to put it another way was the happening of a slip and the presence of a slippery floor unusual, unexpected or untoward. The only reasonable answer, in my opinion, is yes. If there was minimal moisture on the floor from tracking in wetness from outside the co-efficient of friction would presumably not have been lowered that much so that the floor was not so slippery, so the accident would have been avoided.

Equally, when looked at through the lens of the Air France decision, it may be said that the slip was not an internal reaction at its core, it was a slip caused by a wet and slippery floor. To repeat, a wet and slippery floor in, in my view, a plane is unusual and unexpected.

The problem, in my opinion, with the decision is that it appears to determine the case on an incorrect factual basis, namely that there was minimal liquid tracked onto the plane by the passengers which did not make it particularly slippery: it was a normal situation for a rainy day and the claimant’s slip was really just an internal reaction to a normal situation. But that narrative is contrary to the judge’s finding that there was a large amount of liquid and, to use the claimant’s description, it was like he stepped on black ice.

In my opinion this is a surprising appellate decision. In particular Farbey’s J finding, the judge below was entitled to conclude that it would not be unusual or unexpected, from the viewpoint of a reasonable passenger, that a large amount of liquid was tracked into the cabin by the numerous passengers raises an eyebrow. That is equivalent to finding that a wet a slippery floor in an airplane is usual and to be expected on a rainy day.

Standing back and remembering a) Lord Scott’s warning at para 12 of the Deep Vein Thrombosis Group Litigation that judicial formulations of the characteristics of an article 17 accident should not be treated as a substitute for the language of the Convention, and b) O’Connor’s J emphasis in Air France that the Court’s responsibility was to “give the specific words of the treaty a meaning consistent with the shared expectations of the contracting parties” I am dubious as to the correctness of this appellate decision. The claimant’s slip on board an aircraft caused the injury; a large amount of liquid on the floor rendered the floor slippery, and not an internal reaction by the claimant. I consider a slippery floor in an aircraft is unusual and unexpected even if it is wet outside the aircraft and all passengers embark via external stairs. If I am wrong, and a large amount of water and slippery floor in an aircraft is to be expected on a rainy day, such that this event does not qualify as an accident under the Montreal Convention, the case law must (despite judicial warning) have changed the meaning of the words in Article 17(1) so that they no longer retain their ordinary meaning.

Spencer Turner Aviation, Montreal Convention

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