The bizarre aircraft rules that few fliers know about

From blinds and phones to seat cushions, everything is regulated, says John Arlidge

It reads like an April fools’ joke. “British Airways plane banned from flying because seats are ‘too comfy’,” the headline said. And the story? “A British Airways flight from Milan to London was barred from take-off by the Italian government on Monday, thanks to an unlikely culprit. The seats were too darned comfy,” the newspaper claimed. I telephoned British Airways to get to the (ahem) bottom of it. “Er, it’s true,” a senior executive told me, not sure whether to be pleased or embarrassed.

BA flight 575 from Milan’s Linate Airport to Heathrow last month was grounded after inspectors from the Italian aviation authority conducted a surprise inspection of the Airbus A320. They found that the seats in the exit row next to the wings had cushions that exceeded the mandated thickness. Seat cushions in exit rows are thinner than in other rows to make it as easy and as quick as possible for passengers to get off the plane in an emergency. Before the aircraft could take off, BA had to find thinner seat cushions for the exit row.

Absurd? Not really. Aviation is the most strictly regulated form of transport for good reason – but what are the other regulations that you may not know about? Here are my favourites:

Rapid exit

The number of passengers on a plane is determined not by Ryanair boss Michael O’Leary’s determination to squeeze every pound from every square inch of the cabin, but by the number of seats – which is in turn dictated by the number of doors an aircraft has. The more doors, and the larger they are, the more seats. Why? Because airlines and manufacturers have to show that a full aircraft can be evacuated with half the doors unusable within 90 seconds.

The importance of this was illustrated in January when all 379 passenbe gers and crew exited through three doors of a Japan Airlines Airbus A350 which caught fire as it landed at Tokyo’s Haneda Airport. The evacuation took around two minutes. Moments later, the aircraft was engulfed in flames.

Crew cut

The number of cabin crew is determined not by what level of service an airline wants to provide – higher for more attentive service, lower for less – but by a minimum ratio of one flight attendant for every 50 seats, regardless of whether those seats are occupied.

Don’t be dim

Why are the cabin lights dimmed and passengers told to keep window blinds open when taking off and landing at night? You might think it is to make sure cabin crew can see out of the plane in the event of an accident – and to make it easier to see the emergency lights in the cabin that show the way to an emergency exit. But that is only part of the story. Dimming the lights also helps passengers’ eyes adjust more quickly to a dark or smoke-filled cabin.

Blindsided

Blinds are kept open to make sure that, if there is a fire, firefighters can see inside the cabin and identify any flames on board – and their location.

Caught short

There are no specific rules on the number of lavatories an airliner has to have. British Airways recently reduced the number on its short-haul jets – so go before you fly.

Batteries not included

Airlines have to abide by a minimum equipment list. If an important item is missing or defective, the aircraft cannot fly and a strict deadline is enforced for repair or replacement. Something as seemingly small as a battery-powered exit light above an overwing door has to checked before every flight. “If there is a power cut, passengers still need to be able to see where the nearest exit is,” an engineer told Telegraph Travel.

Singles club

All jets have to be able to fly on one engine. Yes, once airborne, a 550-tonne Airbus A380 superjumbo can fly on a single engine. The prospect of single-engine operation helps determine a flight’s routing and the airports it would use if it needed to divert.

Feel the heat

There is no set temperature for an aircraft cabin. It can be anywhere between 18C and 30C. Airlines raise the temperature to encourage passengers to go to sleep and lower it when it is time to wake up. Aircraft can be heated by using hot air which is “bled” off the engines and even by harvesting the heat generated by the batteries that run its computer systems.

A breath of fresh air

There is no requirement that airlines provide individual air vents over every seat. Many Asian airlines do not offer these on widebody jets.

Air has to be filtered every three minutes using HEPA filters, which are also used in a hospital operating theatre. This means you are unlikely to pick up airborne viruses on board – but you may well catch a cold from the constant variations in temperature when you travel.

Window dressing

You might have noticed a small triangle sticker above the window by your seat. This indicates that it is the best window through which to see the moving parts and controls of the wing. The sticker is there to help the cabin crew to be as fast as possible in observing the condition of the wing or an engine in an emergency.

Tipping the scales

Cabin crew tell passengers to “take your assigned seat” before take-off not because they want to split up families but because they have used data on the average weight of passengers to distribute the load evenly around the aircraft for take-off and landing. Every five years, some airlines – including Air New Zealand and Korean Air – do random, voluntary weight checks on passengers in the countries to which they fly. These they use to arrive at an average weight. Passengers are invited to step on to the scales at check in.

Phoney rules

Even though we are all told to switch off our mobile phones, some private flights allow mobile calls and there is little evidence that interference from mobile phones has affected an aircraft’s performance or navigation.

Screen time

There is no regulation size for an aircraft window but some manufacturers like to use bigger windows as a marketing ploy. This is despite the fact that some airlines hate windows because the core is made of glass, which is very heavy.

Tim Clark, president of Emirates, has speculated that airlines will do away with windows and use cameras on the fuselage to project images on a screen in place of the window. That means you could choose which view you wanted to see – the one from the left hand side or the one from the right hand side.

Burning issue

If you have ever wondered why you still see ashtrays on a plane, that is because not every airline in the world has banned smoking. A few carriers in Asia and Latin America still allow it.

i Seat too ‘comfy’? There’s a rule for that j A view on a screen could replace windows