In-flight Internet access...and mobile phones too?

By Paul Parkinson

I read a business article in The Economist ('Mobile Phones on planes - Your call') during the Christmas holidays about the current developments in passenger in-flight systems, specifically the provision of Internet data access and the potential to support mobile (cell) phone voice calls during flight.

The article reports on trials of a Wi-Fi (Wikipedia) data service by JetBlue and Quantas, and a forthcoming mobile phone voice call trial by Air France (which follows on from the mobile phone SMS text messaging described in this Air France press release); it then goes on to discuss the social impact and acceptability of Internet data access and mobile voice calls during flight, which makes interesting reading.

The Internet, mobile phones and satellite communications have all been around for quite a while now, so you could be forgiven for wondering why we haven't seen these technologies rolled out across airline fleets before now? Well, maybe we are only just reaching the tipping point for technology (cost), and passenger demand (revenue)?

At present, the use of mobile phones in-flight is banned in the US by the Federal Communications Commission (and similarly by regulatory authorities in other countries) due to the potential for electromagnetic interference with aircraft avionics. If you perform a Google search, you might get the impression that this is a somewhat controversial subject with polarized views, but there is an example of hard experimental data to support the position on the UK Radiocommunications Agency website EMC Awareness page. There's also the problem that mobile phones passing over ground mobile networks at high speed could cause disruption as the networks struggle to perform handover from one cell to the next.

These new in-flight systems make use of a miniature base station on board the aircraft, known as a picocell (Wikipedia), which connects to a satellite communications network to avoid both of these problems. This works because mobile phones transmit on increasing levels of power until they get a response - the concept is that if they receive a response from a nearby picocell they continue to transmit on low power levels, which will not interfere with aircraft avionics or reach ground-based networks thousands of feet below.

Despite this technological advance, I have to admit that I would try to avoid being on a flight where mobile voice calls were possible. This has nothing to do with the safety aspect, but because of the disruption. People tend to talk more loudly on mobile phones than on land lines because the sidetone on mobile phones is less than on landlines (sidetone is where the speech from the microphone is redirected to the speaker at a lower level, so that the person can hear what they are saying). If you now factor in the noise from the air-conditioning and jet engines, you've got a recipe for loud background chatter. The Economist article doesn't mention if these systems will support in-coming voice calls, but I certainly wouldn't welcome the sound of ringing mobile phones either, especially on a transatlantic flight, especially when I am trying to get some sleep! Maybe the reason why the airlines are being cautious about the introduction of voice calling is because they are wary of adverse passenger reaction?

On a positive note, I would very much welcome in-flight Internet data access, as it enable me to catch up on my email backlog, especially on long transatlantic flights. As an aside, my view on this isn't affected by the news story 'FAA: Boeing's New 787 May Be Vulnerable to Hacker Attack ' (Wired.com) which was posted earlier this week and was rapidly seized upon and somewhat sensationalized by the wider media. The Wired article, includes mention of "multiple networks", "isolation" and "air gaps" (i.e. physical separation) but doesn't really explain the concept of aircraft networks, which would have provided some useful context.

Basically, aircraft have a number of different type of networks, or domains, which connect systems which perform different functions; these typically include Flight Deck, OEM, and Passenger Systems. The networks have different networking requirements and are separated by firewalls for safety and security reasons (see ARINC 664 for more details) - one aircraft design already in-service is reputed to use a hardware diode to only allow the flow of data in one direction only between networks. In any case, so I don't think this story should be a cause for concern for 787 passengers. Back to in-flight Internet access, I wonder if other laptop users would be trying to use Skype to make Voice-Over-IP (VOIP) calls? If so, I hope they don't sit near me.

So Is it finally time for take-off for in-flight Internet access?