E-Cabin: A workplace in the sky


A workplace in the sky

By Jim Sparks
Photo By Jim Sparks

November 2001

E-CabinAircraft have often been recognized as one of the primary achievements in making our world smaller. It is now possible to travel virtually anywhere on the globe within a 24-hour time period. When this phenomenon first came into existence, it was a real challenge for the airlines to figure out how to keep the passengers occupied for extended periods of time. If nothing else, people could settle back and listen to the drone of the engines while staring into the vastness of what is the world of aviation.

A workplace in the sky
In the past, a day of travel meant reading the paper or a good book along with AMT Magazine, then taking a nap or getting a deck of playing cards from the flight attendant only to be disturbed by a first-class food service, and then resuming the nap until landing. Today, air travel means not interrupting business as usual. Both airlines and manufacturers of business aircraft have adjusted to this fact. The pomp and elegance associated with lounging and relaxing is rapidly making way for a workplace in the sky.

Noise control
Cabin noise control is often an issue where enhancements are needed over and above standard insulation packages. Generally, the larger the cabin, the greater the ability to naturally dampen sound. In smaller aircraft, this can be achieved through vibration damping interior attachments. Still, some passengers are sensitive to elevated decibel levels and may require special techniques such as "Black" or "Negative Noise." This is most effectively provided on an individual basis through a "Noise Canceling Headset," a device that senses ambient cabin noise in specific frequency ranges and then produces a frequency the same as the offending sound — only 180 degrees out of phase. This effect will negate the noise. In addition to the standard audio input, this specialized device requires a dedicated power supply, typically accomplished by supplying a separate electrical plug that installs in a receptacle located within close proximity to the audio jack.

Communications capabilities and challenges
Communications capabilities are most often the paramount factor in maintaining a successful business. This one factor is with out doubt recognized by airlines and business aircraft manufacturers alike. It has been possible now for some time to place telephone calls from an aircraft to virtually any other telephone on the ground or in the air. This capability has posed many challenges to system designers. First of all, a high speed aircraft operating six or seven miles above the earth at nearly any point on the globe will not be conducive to the standard cellular telephone technology. Satellite Communications (Satcom) provides one answer. Inmarsat (International Mobile Satellite Organization) operates a series of four operational communications satellites operating at high altitudes over the earth’s equator.
The principle here involves the aircraft locating and then establishing communications with a satellite within the same quadrant of the hemisphere as the aircraft. A link is in place from each satellite to strategically located ground stations. Once the downlink is complete, the ground station couples the communication from the aircraft into the local ground based telephone system. The first challenge is for the aircraft to locate the appropriate satellite. This requires the use of computers that can calculate the satellite’s coordinates. Once this is achieved, the aircraft needs to know where the target is relative to the aircraft and involves the onboard navigation systems coordinating with the satellite communication equipment and then positioning a directional antenna to locate and then lock on to the satellite transponder. When a lock on is established, transmissions can occur. The high altitude trajectory of the satellite requires the aircraft to communicate with a high power amplifier. This type of communication is rather costly on a per minute basis and up until recently, the data transmission speeds were such that it was not an economical means of retrieving email.
Inmarsat has just announced that by the end of the year, a high-speed data transmission service will be available. Users will now be able to access the Internet on Satcom-equipped aircraft at 64,000 bits per second now and up to 432,000 bits per second by 2004. Although this system will work using existing equipment with minimal change, an onboard computer server may be required. There is still some concern that an abrupt maneuver of the aircraft may cause a disruption of the data link with this type system.
In addition, Honeywell Avionics has teamed with Thales Avionics to produce a new seven channel Satcom system. It is advertised to produce enhanced long range voice and data communication with the ability to interact with alternate satellite constellations. This includes the future Aeronautical Telecommunications Network (ATN) — a segment of the plan to prevent overtaxing communication radio frequencies by replacing voice communications with digital messages.


Magnastar Airborne Receiver Transmitter Unit

Another device allowing air to ground or ground to air communications is MagnaStar®. In contrast to Satcom, this system works on a principle that is actually similar to a cellular telephone network. Presently, this system is limited to flights over the Continental United States with fringes in Canada and Mexico. A group of well over 100 ground stations wait to establish a connection with an appropriately equipped aircraft. This type system can support several telephone conversations at any given time along with a data link to update the AirShow system, which will give passengers up-to-the-minute stock reports, weather briefs or breaking news reports along with Internet connections. At the same time, MagnaStar can provide a dedicated fax line. When outfitting an aircraft with this technology, it is essential to make sure that existing fax machines that will be used to communicate with the aircraft are compatible with the MagnaStar system.
The principle here requires the fax sender on the ground to dial the aircraft number and initiate the communication. Once the aircraft receives the signal, the onboard fax machine dedicated telephone line calls back down to the transmitting ground station. It is only then that the two fax machines can actually begin communication. The main problem in establishing a link is to allow adequate time for the connection before the timeout occurs resulting in disconnect.
Data link is another feature available with several Air/Ground communication systems. Although the baud rates are relatively low system, manufacturers are forecasting high-speed connections in the near future. Yet, current baud rates can provide significant distress. When someone plugs a laptop computer into an aircraft data port and initiates communication with a ground-based computer server, the laptop modem tries to communicate at the highest speed available. If it can not establish a link, it will try again at a lower rate. By the time the computer gets down close to the rate at which the aircraft can communicate, a timeout occurs and the connection is lost. Some frequent fliers have computers that are set to communicate deliberately at slower speeds so as to provide fewer disconnects.
DeCrane Aviation recently announced capability to provide a truly high-speed Internet access. The 512,000 bit per second (512 KBPS) data transfer is possible by using an Integrated Service Receiver (ISR) interfaced with the ViaSat Ku-band satellite system.
Honeywell has also announced that they plan to bring to market an In Flight Mail system using a high speed Inmarsat Satcom link. The plan is to be able to send large email message attachments at the new 64kbps. The system is designed around Honeywell’s Total Aircraft Information System (TAIS). This consists of an onboard server and router. Presently, the system is being tested using the Iridium low earth orbiting satellite system. Although the Iridium service transmits at a rather low 9.6 kbits, text messages can still be sent through with only about a 30-second phone call to pass the data. One benefit of the TAIS server is the ability to work with a variety of different email systems, which means additional user software is not needed. Plus, the system is capable of data compression as well as encryption to ensure fast yet secure transmissions. Along with some additional aircraft equipment, TAIS requires operational software running in a ground-based center. The Honeywell Data Center (HDC) is in Phoenix and contains a number of servers connected to communication links and allows the operation of email from the Internet or corporate networks. This data center provides the capability to connect a persons email account and the on board computer server.

Power sources
Using personal computers on aircraft require the availability of operating power. A battery pack is not always a good plan when an important project completion is planned while on an airline journey. Plan for job obstructions. If necessary, take along a spare battery or two. Also save data frequently. Many business aircraft have onboard power that conforms to that available at the home base. In the United States, this often involves the installation of an Inverter capable of producing 115 Volts AC at 60 Hz. Many airlines even provide power outlets at business class seats. One drawback is they usually do not provide the adapter cable to go from the outlet to the computer. Often these can be a real value for those of us that travel frequently and end up using travel time to complete assignments.
Like many other frequent fliers, I have spent countless hours banging away on the keyboard of my laptop computer while winging my way to some far off destination. I have witnessed my fellow passengers having coffee spilled on their keyboards along with having their batteries go flat after hours of work without saving the data. Good, bad, or otherwise, the concept of the office in the sky is here to stay. For those of us who like to recline the seat, turn off the light and listen to the drone of the engines, it means despite of all the electronic cabin amenities, we still may get a nice rest.