Current opinion: none
For the last years (decades?) airlines have had a difficult time. Over the years, airline ticket prices have gone down significantly when taking inflation into account. Airline security has increased. Airline fuel prices have skyrocketed. Low-fair airlines have come into play.
Anything that affects their bottom line can be a burden. But is the occasional passenger, who is too large to fit into one seat, really a burden?
I could not find any statistics on the number of airline passengers who pay for one seat and take two, or who pay for two seats for one person.
Different airlines have different policies. Continental and United Airlines require passengers to be able to lower both armrests and fasten their seatbelts with one seatbelt extender. Delta and Northwest (now merged) require passengers to be able to fasten their seatbelts, without extenders. Southwest requires passengers to be able to lower both armrests. American Airlines policy was vague for the information I was able to find.
Of course, airlines have some leeway in these policies. They certainly wouldn't require passengers to pay for two seats if the airplane was not a full capacity.
But what if the flight is full, and the plus-sized passenger has purchased only one ticket, and cannot put both armrests down?
Some airlines and aviation officials cite 'safety' as the reason a plus-sized passenger should not be seated into one seat. In addition, what about the passenger sitting next to them? Imagine riding across the country with an arm pressed into your side the whole journey. Robert Evans says
A skinny airline passenger has rights too.
Here is a photo of one passenger who was allowed to fly that is an obvious safety issue.
Passenger creates big debate at American (FlightGlobal.com). The plus-sized passenger is doing his best to accomodate the passenger to his right. But at what cost?
On the large passenger side, many people cannot help being the size they are. For various medical and genetic reasons, they are the size they are. Maybe they could 'thin down' a little, but some people are just big.
More and more people are 'in the news' about issues concerning flights.
Overweight passenger denied seat on Southwest flight (ABC News). Even the filmmaker Kevin Smith was denied his flight earlier this year.
Kevin Smith Too Fat to Fly (ABC News).
Here is a good article on both sides of the issue. I think Canada has a good idea that the FAA should adopt.
Extra charge for extra-large airline passengers (Seattle Times).
Lastly, Grand Style offers
Airline Tips for Large Passengers.
New opinion: (changed) Unless the FAA adopts the Canadian 'medical excuse' plan, plus-sized airline passengers must be able to put both arm rests down and fasten their seatbelts with one extender. Otherwise, they should pay for two seats when they book. If the flight is not full, the airline will refund their second seat price. If they did not book two seats and the flight is full, they will need to take a later flight, booking two seats.
UPDATE:
Petite woman bumped from plane for hefty passenger (MSNBC.com)