Spending couple of weeks down the south coast of New South Wales, spotting dolphins and echidnas, has slowed down my blogging. Fortunately, regular contributor James Glover has once more come to the rescue with a guest post. This time his topic is wheelchairs and air-travel.

Perhaps you’ve heard of a recent court case in which a wheelchair user, Sheila King, took Jetstar to court (and lost) on the basis of the Disabilities Discrimination Act? If you are a wheelchair user and you book a flight on one of our airline carriers then a fairly obvious thing won’t happen. Unlike say a bus you won’t be able to board the aircraft in your chair and be strapped in for the journey. What actually happens is that when making the booking you tick a box (or tell the booker on the phone) that you are in a wheelchair. If there are seats available for wheelies when you get to the airport you will give up your chair and be made to use a specially designed “wheelchair” (its a chair, it has wheels) that is designed to be fit the narrow corridor of most planes which I am sure you are aware of – their narrowness, for you, only apparent when the person ahead of you is blocking the aisle loading 3 pieces of carry on luggage into the overhead lockers while chatting to their new friends in the seat they are meant to occupy. We all suffer this situation. These “wheelchairs” are not designed to be used without help, they are more like children’s toy carts and cannot be operated by the user as the wheels are very small and low down. For a wheelchair user to be taken out of their wheelchair in a public place can be quite discombobulating. Many wheelchair users develop a personal relationship with their chair – it is after all a place you spend many of your waking hours.

Digression. The very first time I was in a wheelchair outside the confines of a hospital ward (it was a hospital wheelchair but is the exact same model I now own, like I said it is personal) I was being pushed by none other than the proprietor of this very website! Without going into the details let’s just say it was a pretty dramatic event and we both learned a valuable lesson in wheelchair use and the wheelchair repair workshop at the hospital was kept busy. But I digress.

So here is the thing. According to Google about 1% of the population uses wheelchairs. And a Jetstar plane has about 200 seats so they expect to get about 2 wheelchair users on average per flight. So what is the problem with only allowing this same number on each flight, as some airlines do? Well the problem is that statistically wheelchair users don’t travel in pairs and sometimes there will be less than 2 users and sometimes there will be more. Just as if you toss 10 coins sometimes there will be fewer than 5 heads (the average or expected number) and sometimes there will be more. Only on average will there be 5. In fact it is a simple problem to work out the probability of there being, say, n wheelchair users, given the average of 1% on a 200 seat plane. This is called the Binomial Distribution. If you have access to Excel then the function Binomdist(n,200,1%) will tell you this probability. Before I give you some numbers I admit that the overall population average may not be the same as the average flying on planes. It may be less than 1% due to wheelchair users being put off flying. But maybe on some routes it is higher: but I am guessing the annual “snowbird” migration of retired people from the northern United States to Florida at the start of Winter would track above the 1% rate.

So here are the Binomial probability figures.

For example, assuming a 1% chance of any given passenger a 200 hundred seat plane being in a wheelchair, the probability that there will be exactly 4 wheelchair passengers wanting seats is 9%. To work out the probability of a passenger being denied a seat on their preferred flight, we will assume that we’re dealing with an airline where more than two wheelchair passenges book on a flight, then at least on passenger will have to change their travel plans. From the table above, the chance of the flight only having 0, 1 or 2 wheelchair passengers totals 68%, so there’s a 32% chance that there will be at least one wheelchair passenger who cannot fly. For any one wheelchair passenger, there is a (n-1)/(n+1) chance of being bumped if n other wheelchair passengers book on the flight. Weighting that by the probably that there are n passengers and adding it up for all n>1 gives a probability of 27%. As a frequent flyer in a wheelchair, you can expect to miss out on a seat quite regularly! [Note: these calculations have been updated: the editor’s “corrections” were undone. Ed.]

I am quite fortunate now that I no longer need to travel in my wheelchair. But as I still use a walking stick I wait for everyone else to get off the plane. You sit there, looking behind you to see if everyone else has left. But there are always these strange people who seem to sit there at the back of the plane and wait for 10 minutes or more, after everyone has disembarked, before even moving. You wonder why the airline staff don’t just hurry them off? I assume they aren’t disabled because they are sitting at the back of the plane. If airlines really had a problem with the extra time that getting wheelies off the plane then they could make this up by just moving these people along.

When I first read about this case my initial response was that being disabled and traveling is a bit of challenge anyway and you just get on with it. But the more I thought about it I wondered if the airlines just took it for granted that wheelchair users would change their plans to fit in with the rules. I am glad Sheila King took the issue up!