ATM Modernization, Business & GA, Commercial

In-Flight Cell Phones

By George Marsh | October 1, 2005
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At A Glance

European advocates of onboard
cell phoning hope to obtain licenses in 2006. In this article we examine the state of play regarding:

  • Certification challenges and
    interference mitigation technologies such as picocells and frequency sensitive surfaces;
  • Airborne servers, telco challenges, and fees and costs.

European air passengers are just as keen as their American brethren to continue talking on their mobile phones while flying. In a survey of 1,200 international passengers conducted at London's Heathrow and Gatwick airports, nearly half said they would prefer to travel with airlines that allow the use of mobile phones in flight. Almost a third of respondents said they would be willing to pay $3 to $6 per minute for in-flight mobile service, while more than half would send and receive text messages. The survey was conducted last summer by the UK consultancy, In-flight Management Development Centre (IMDC).

It looks, on the northeast side of the Atlantic at least, as though passengers might be close to satisfying their phone hunger. Under the plans of the two main European in-flight connectivity players--OnAir, a SITA/Airbus collaboration, and ARINC/Telenor's AeroMobile--service could start as early as next year. The two partnerships have demonstrated their technologies.

Change, moreover, is in the air. Whereas up to a year ago the current bans on in-flight use of mobile phones appeared virtually immutable, regulators may now be softening their stance. Full approval, though, depends on the safety authorities' (particularly, in Europe, the European Aviation Safety Authority's [EASA's]) being satisfied that in-flight cell phone technology will not affect safety-critical aircraft systems. At the same time, telecommunications companies (telcos) want to be sure that onboard equipment will not interfere with ground cellular networks by "splashing" disruptive emissions across several base stations.

In short, there remain significant concerns over safety, social management and security (August 2005, page 65). And these can only be fully addressed by accumulating in-flight experience. Given those concerns, it behooves the industry, safety authorities, telephone companies (telcos) and regulators to move forward with hope and determination, certainly, but also with caution. It is in everybody's interest that this technology comes to be seen as an enhancer rather than a disrupter.

Airborne cell phone use certainly can, for example, disrupt the solitude many passengers seek from air travel, granting them time to simply read a good book. Flight attendants are wary of having to police the use of cell phones in the cabin. And U.S. agencies have raised the prospect of terrorists' using cell phones to coordinate a hijacking or attack. But perhaps the biggest safety concern is radio frequency (RF) interference to both the onboard avionics and to the terrestrial base stations, should a cell phone seeking a connection over a long distance boost its emission--by as much as 10,000 times, according to one telco.

Mitigating Danger

Technologies to mitigate these dangers continue to be developed. The most widely favored solution is to have passenger phones "surrender their autonomy" to an onboard wireless base station, known as a picocell. This device takes control of the handsets and commands them to operate at power levels below those that could cause interference to critical avionics. Passenger phones that are enabled for international roaming log on to the onboard wireless network and communicate with it at low power. The picocell base station then transfers digital call content to terrestrial networks at controlled power levels.

A picocell not only limits the power that individual phones can emit, but also enables the cabin crew to interrupt or reduce connectivity. Service could be discontinued, for instance, when an aircraft is flying over a country that has not granted a license for overflying cell phone operation, or when cabin safety or other announcements need to be heard. Communication can be restricted to text only during sleep interludes or other allotted quiet times.

OnAir and AeroMobile both have developed picocell-based solutions. And Honeywell has followed suit, primarily targeting corporate aircraft. AeroMobile also has adopted a fallback protection system. Intended to maintain safety should the primary picocell system fail to operate as intended, the backup protector works by raising the white noise threshold in the cabin sufficiently to block any rogue, high-power transmissions from passenger phones. Roke Manor Research in the UK (owned by Siemens) is developing such "noise lifter" technology.

Another possible mitigation is to incorporate within the aircraft structure windowpanes and panels that block selected frequencies. Researchers at the University of Warwick, UK, have been developing such frequency-selective surfaces (FSS), primarily to enhance information security in commercial premises but with a possible aviation spinoff.

Ericsson recently launched a picocell called the RBS 2708 base station. While the Swedish company is loath to divulge the exact nature of its technology, simply referring to it as an "electromagnetic screening device," it is confident in the base station's ability to prevent interference with both aircraft avionics and terrestrial networks. Part of Ericsson's overall "GSM on Aircraft" solution, the picocell appears to a telecom operator as just another network cell. Operating in the 1800-MHz band, which supports the GSM protocol used in much of the world outside North America, it can handle up to 60 simultaneous calls to and from passengers at cruising altitude. Involvement needed from the cabin crew to operate the system is said to be minimal. Housed in an ARINC 600 box, the base station should be easy to install and maintain.

Ericsson has sought to future-proof its product by making it compatible also with the next-generation Enhanced Data Rates for GSM Evolution (EDGE) protocol and the General Packet Radio Service (GPRS) already available for Blackberry-style, portable e-mail devices. Both of these protocols have higher data rates than present GSM. It also may be possible to upgrade the unit for the future 432-Kbit/s Universal Mobile Telecommunications System (UMTS) standard.

Thus the system should, in due course, be able to support a wide range of wireless communication solutions offering e-mail, Web, Intranet and other broadband benefits from a variety of personal electronic devices (PEDs). Company spokesman Peter Olofsson is confident that present regulatory issues will be overcome and says that early examples of the system should be ready for installation on aircraft in late 2005.

Cell phone service proponents accept that certain objections to in-flight usage may have been justified, but they argue that the mitigations now becoming available will be fully effective in preventing interference. They are well aware, though, that acceptability will vary from region to region, according to social, political and regulatory factors. For instance, in certain areas--North America, particularly--cabin staff have objected to the prospect of passengers' using their own phones in flight.

Cabin Staff Concerns

Flight attendants not only fear disruption to aircraft systems, but also have health concerns and worry that phone usage could disturb passengers who view air travel as an escape from overheard cell phone conversations. Extra demands in cabin management and diplomacy are likely issues, too. Keen interest exists in a report from an International Air Transport Association (IATA) medical committee on health and safety of flight attendants. The committee is investigating whether working close to a picocell could constitute a health hazard over time. (Aspiring service providers say this is unlikely, since emission levels from picocells will be well below those accepted as safe for cell phone users.)

OnAir and AeroMobile have both sought to allay flight attendants' fears about social factors, arguing that properly engineered picocell solutions give cabin staff all the control they could possibly need to restrict or discontinue connectivity according to conditions on board and company policy. Others have pointed out that such systems should actually be safer than present arrangements under which passengers are simply asked to keep their phones turned off and cabin staff have no control over them. In any case, it is argued, pricing levels will tend to inhibit frivolous phone use and limit the number of calls taking place at any given time.

Monitoring RF

Another technological safeguard under consideration is to provide the crew with an indication of picocell serviceability. This should help prevent passenger phones from reverting to high-power operation if there is a picocell failure. A report from the European Organisation for the Safety of Air Navigation, issued last December, suggested that the overall radio frequency (RF) field strength within an aircraft should be monitored. This would both alert the flight crew to any undue rise in the RF level that might affect aircraft systems and gauge the volume of passenger use of the onboard cell phone system.

Various demonstrations have shown encouraging results for mitigation technology. During a key European Commission-sponsored wireless cabin demonstration program that took place on an Airbus A340-600 during 2003 and 2004, a Siemens picocell used in conjunction with software from German company TriaGnoSys provided all the protection necessary, along with the capacity to support telephone voice and text service. According to Axel Jahn, managing director of TriaGnoSys, "Our software will provide fully automatic control of all GSM services, including voice, data and SMS [short messaging service], in all phases of flight."

OnAir Prepares

OnAir has selected the Seimens and TriaGnoSys elements, along with an airborne server from Miltope, as the basis for its airborne GSM architecture. It is working to have a complete onboard system ready for integration with its ground infrastructure, preparatory to full, end-to-end testing, by mid-2006. OnAir will then have to demonstrate to EASA and Europe's terrestrial wireless telecommunications interests that its technical solution is airworthy and non-interfering.

Airbus is taking the lead in integrating and certifying the onboard system, largely through its German subsidiary, Airbus KID-Systeme. "We're focusing on certification through our shareholder, Airbus, which can do the necessary tests in a way that few others can," Andrew Charlton, OnAir's director of regulatory affairs, told interested parties at a recent London briefing. "The next step is an agreement with EASA on what exactly needs to be tested, as part of the certification procedure."

"Ours is certainly not a cheap and cheerful approach--far from it," Charlton adds. "But the work is continuing smoothly, and we expect to see it concluded by the middle of next year."

KID-Systeme first will develop a GSM system, including the necessary picocell, server and cabin antenna, for A320 aircraft operating on west-European routes. Part of the onboard equipment will be a control panel that the cabin crew will use to select the required service mode and monitor the system. Inputs of position, altitude and other parameters from the aircraft avionics will help flight attendants maintain awareness of the prevailing flight phase, serving as a guide for their mode selections. After A320 integration, the system will be implemented on other Airbus types, supposedly before the end of 2006.

Boeing, Too

OnAir's chief executive officer, George Cooper, emphasizes that, notwithstanding the Airbus integration lead, its solution will be equally suited to Boeing aircraft. "Voice and data, Airbus and Boeing, long and short haul," is the company's boast for its technology. Airbus has announced its intention to make the OnAir service available as a standard option to its aircraft customers.

OnAir incorporates the e-mail messaging strengths of the former Tenzing Communications, having absorbed that organization at the time of its own incorporation in February 2005. Although OnAir has its headquarters in Geneva, Switzerland, much of its expertise resides in Seattle, where Tenzing was located. The telephony and short messaging services developed by SITA are also part of the joint portfolio.

OnAir decided early that its service at first will be offered only during cruise flight and will be discontinued during takeoff, climb, descent, approach and landing. This will, it hopes, both facilitate early certification and avoid antagonizing current providers of service to aircraft at gates and taxiing.

Telco Challenge

While airworthiness certification is a major issue, an equal challenge is satisfying multiple telcos that existing terrestrial services will not be adversely affected and then persuading them to grant licences. A Spectrum Engineering Working Group of the European Committee of Posts and Telegraphs (CEPT) administrations is studying the interference issue and due to publish a draft decision based on its findings for public comment.

In theory it would be necessary for every airline intending to offer in-flight cell phone service to seek approval from the national telecom licensing authority for each country that will be overflown. Given that there are 42 such bodies across the European land mass, this could become a bureaucratic nightmare.

OnAir is trying to circumvent this by pioneering a more rational regulatory approach that will operate at regional level. The idea is that operating licences will be issued to compliant airlines by the states in which their aircraft are registered. Other countries that are overflown will recognize these licences. Those countries will, in turn, have their licenses recognized reciprocally. The 42-nation CEPT has begun to form the harmonized, regional framework that would make this possible and, according to Charlton, this should be ready by spring of 2006.

"As soon as one nation has licensed one airline," asserts Charlton, "there's no reason why we should not begin to offer service." Similar arrangements are in the early stages for other regions, in particular the Gulf and Asia-Pacific.

OnAir has letters of intent from three airlines to purchase its GSM solution and expects to finalize these and other deals over the next few months.


Having officially launched their joint AeroMobile brand earlier this year, partners ARINC and Telenor likewise aim to inaugurate onboard GSM in 2006. Like OnAir, AeroMobile intends eventually to expand this to include Web browsing and other high-data rate features. Both providers will utilize Inmarsat satcom to underpin their services on long-haul aircraft, a prime target for onboard connectivity.

Inmarsat geostationary satellites provide service that is near global, excluding only the polar regions. Airlines whose aircraft already are fitted with classic Inmarsat Aero I, H and H+ equipment will be offered GSM service permitting up to half a dozen phone calls to be made at the same time. However, advanced payloads on the fourth-generation satellites now being orbited will, within a year or so, support Inmarsat's intended 432-Kbit/s SwiftBroadband service, and this will raise the potential number of simultaneous calls to about 30. It will enable users of advanced cell phones to avail themselves of other broadband benefits, as well. Terrestrially based ground-air link options will be offered for short-haul operations.

AirMobile has selected a picocell base station from IP Access of Cambridge, UK, for its system. Connectivity specialist AltoBridge will provide the controlling software. (This Irish company also supplies the software for Honeywell's onboard cell phone solution.) AltoBridge says its proven AM (aeronautical/marine) gateway platform is hardware-agnostic and can support two-way wireless communications via both terrestrial and satellite systems, as well as a variety of user phones, laptops and other PEDs. Running on a cabin server, the software controls the operation of the picocell and provides the gateway between the airborne communications system and the ground network.

Initially AeroMobile, like OnAir, is concentrating on providing GSM service during cruise, on the basis that it will not at first be permitted for other stages of flight. However, it intends to show that service can safely be extended to other times, such as during pre-landing holds and at the upper levels of climbs and descents. Voice and text messaging will be supported, on single-band or multiband phones.

Fees and Costs

In acting as an aeronautical mobile operator to enable cellular roaming between aircraft and ground mobile networks, AeroMobile aims to allow passengers to use their mobile phones exactly as they would on the ground. Bills will be presented in the normal way by existing network operators. Although the partners have mentioned price targets of $3.50 per minute and $1 per outgoing text message (incoming free) for use of the service, their stated policy is to allow airlines to set the rates. In any event, charges probably will be much less than those currently levied for using airline-provided in-flight phones (typically $10 per minute). This should help breath life back into onboard telephony. Costs for typical hardware--one or more picocells, a server, a cabin control panel and an optional cabin antenna--are estimated to be less than $100,000.

Earlier this year the company AeroMobile demonstrated its GSM solution at the new Crawley offices of partner ARINC near London. Visitors to an event hosted by ARINC were able to try out a prototype installation, which used Telenor's ground infrastructure operating with Inmarsat Aero H and H+ satcom systems. AeroMobile's GSM technology flew in prototype form on a Boeing B777-200LR Worldliner that was seen at this year's Paris Air Show and went on to make a demonstration world tour.

Now that a standard for interference has been developed by Europe's GSM/EDGE Radio Access Network (GERAN) group, system design can be further refined. AeroMobile expects its definitive system to fly on several aircraft in the near future. According to program director, David Coiley, a number of potential customers are in the advanced stages of negotiation, and the first airline retrofits should take place soon.

While differing in their estimates of the difficulties involved in achieving the necessary regulatory framework, the two service players see eye to eye on key aspects and are dovetailing their campaigns, focusing particularly on CEPT and the Federal Communications Commission (FCC) in the United States. A divergence in market approach arises, however, over the corporate aviation sector, which AeroMobile, unlike OnAir, plans to target at an early stage. For this reason, it intends to include in its technology provision for the code division multiple access (CDMA) cellular standard used in North America. It appears undismayed by the prospect of competing with Honeywell in this sector.

Mid-2006 launch?

Both communications providers, along with their suppliers, appear confident that regulators will give their services the green light and the necessary licenses will be obtained before late 2006. Both also are convinced that there is firm demand for the service.

As OnAir's George Cooper has commented, "We know there's a strong market for onboard passenger communications, and we have seen interest from airlines across the world. The letters of intent we hold show that our predictions are correct, but it's great to have that validation."

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