Why Don't Airlines Allow Cell Phone Use During Flights?

The short answer to this question is that some airlines do allow it and some don't.

Several airlines outside the USA do allow the use of cell phones; some examples are: Emirates, Virgin Atlantic, British Airways and Egyptair. This has led to some people calling for their use to be allowed on planes in the States too.

But it would be very misleading to suggest that you can hop on a British Airways plane and use your phone at 35,000 feet to let your mother know you are coming for a three day visit and will be home in time for tea.

Even within the companies that allow for the use of cell phones, there are only a limited number of planes on which this is possible. And there is a very important reason for this.

Cell phones work in the same way as a radio: they talk to a transmitter-receiver that has to be in what is known as “line of sight” nearby. This doesn’t mean we can see it, but that the radio waves can. On top of a mountain in a desert it could be further away than in a built up city because there would be no buildings to cause interference. In the US these cell phone transmitter-receivers are known as towers, and in the UK they are called mobile phone masts. Each tower or mast has an area of coverage and when you go out of range of one your phone will pick up a signal from another.

Cell phones react in ways that can reduce or increase the power they use. When a phone is searching for a signal it uses high power. When it finds a signal, if the phone is not being used to make calls it will go into a low power state, and then goes back up to high power if you make a call.

If you try to use a cell phone in a normal airplane, it won’t work for two reasons: the plane will be travelling too fast between transmitters to maintain a connection, and besides, once above around 3000 feet, cell phones simply cannot pick up a signal from the ground.

All the planes from which it is possible to use a cell phone are fitted with a “mini-cell.” This is a low powered version of the cells in transmitter-receivers for mobile phones. Because it only needs to pick up signals from phones within the airplane, the mini-cell doesn’t need the same amount of power as a ground-based transmitter. The airplane’s cell does not connect to ground based transmitters; it connects via satellite.

Anywhere there is fuel – be it a gas or petrol station or in areas of an airport where planes are refuelling – it is unwise to use a potential source of ignition. Cell phones are one potential source of ignition. You may think because you see airline staff talking on walkie-talkie radios that it is safe to use a mobile phone, but those walkie-talkies have much lower power. Occasionally you may even see staff using mobile phones. Again, that doesn’t mean it is okay for passengers to do so. Staff members know the airport environment well, and they know where it is safe to use their phones. Passengers don’t.

Once inside the plane, most airlines allow use of cell phones on the ground up to a certain point. This point varies from airline to airline but that doesn’t mean some are getting it wrong; it simply means airlines need to decide on a clear point that is easy for cabin crew to instruct passengers to switch off. Common times to give this instruction are when doors are closed or when the engines start.

The particular concern with cell phones and other personal electronic devices is their use at critical stages of flight: that is at take-off and landing, with landing being the most crucial.

Leaving a phone switched on means it will start searching for a signal as the plane takes off, and so will go into high power. At other end of a flight, as the plane descends it will again power up as it comes into range of ground-based cell phone towers or mobile phone masts. There is a large amount of anecdotal evidence from airplane crews of interference with equipment. How much interference occurs can depend on a number of factors, including where the cell phone is and how the wiring of the plane is routed. In a plane with wiring running close to overhead lockers, a phone in a locker could cause interference, whereas one below the seat might not. However, the wiring of a different plane might take a different route, so you can’t assume it’s okay to leave a phone in a seat pocket and switched on!

In October 2012, a report in USA Today stated that, “The FAA found no reports of cell phones interfering with navigational equipment in its study of their use abroad on foreign airlines.”

However the CAA (the UK Civil Aviation Authority) sees this a little differently. In 2009 it published research findings that showed mobile phones could affect navigation and communication systems, leading to errors on instrument panels and creating background noise on pilots’ radios. Some instances they noted were:

• false notification of unsafe conditions – for instance warnings of smoke alarms in the baggage compartment when no warning was in fact given;
• disrupted communication because of noise interference in crew headphones.

Why the difference in these two perspectives?

The CAA’s research was into airplanes that were not fitted with the mini-cell. The aircraft studied by the FAA were fitted with the mini-cell.

The world-wide recession, the increase in cost of aviation fuel and the decrease in cost of airfares has had an impact on earnings for many airlines. One reason many of them are keen to install mini-cells in their aircraft is because these are a way to generate extra income. Virgin Atlantic charges $1.29 per minute, and some companies charge considerably more.

Even in countries where the use of mini-cells in aircraft is allowed, the use of any personal electronic device during take-off or landing is prohibited. Even though some people argue that phones have been left on during take-off with no serious consequences it is extremely unlikely that authorities will ever allow this. Part of the challenge facing airlines is that the trials so far have been fairly small scale. There could be big differences between a few people using a cell phone while the plane is safely in the air, and 180 people using their phones during take-off or landing.

With so many unknown factors and no compelling reason to allow it, airlines are likely to err on the side of caution. For landing in particular, if conditions are poor, pilots rely on instruments to guide the plane safely onto the runway.

An airline captain's perspective:

My husband is an airline captain with over thirty years experience of flying, and this is what he says: “ During an automatic landing onto a 45 meter wide runway at 150 miles per hour in zero visibility, the last thing you want is unpredictable interference."

With thanks to my husband, Jerry Thomas for sharing his expertise for this article.