The promise of in-flight connectivity (IFC), or in-flight Wi-Fi, that seamlessly provides passengers with an experience and capabilities near-equal to what they are used to receiving on the ground has yet to be fulfilled.
Why is this?
There are two conditions that must be met for a technology to become widely adopted:
- The technology must enable a large number of people to do something they want to do, often.
- The technology must be affortable.
To date, IFC systems have missed the mark on both counts, neither meeting customer expectation nor offering affordable prices. . However, if IFC service providers were to make significant improvements, airlines could consider offering free in-flight Wi-Fi to their passengers, as Delta CEO Ed Bastian said at the 2020 Consumer Electronics Show (CES) in January. Bandwidth may be a luxury item for older generations, but it is a necessity for younger flyers, who represent future airline demand. Significant IFC improvements would give an airline a competitive edge in the pursuit of frequent travelers. As the COVID-19 outbreak subsides, airlines will be in a position to turn some focus to IFC.
What do flyers want to use IFC for when they’re in the sky? An annual assessment of Internet traffic provided by Sandvine, a leading authority on global and regional internet traffic, provides a point of comparison. According to Sandvine, the top six applications and associated percentage of web traffic are:
- Video streaming at over 60%
- Web browsing at 13%
- Gaming at 8%
- Social networking 6%
- Filesharing at 4%
- Shopping at 2%
For an IFC service provider to be successful, the service must enable passengers to use the most popular Internet application — streaming video — but current IFC systems lack the capacity. It’s akin to an electric utility prohibiting customers from running their air conditions or turning on their lights; why would a customer pay for that service?
For IFC to fulfill its promise, it must provide each airplane with sufficient bandwidth to enable a substantial fraction of all passengers to access their preferred video streaming service. A service which enables most or all passengers to access Netflix or any other streaming video service would most likely have sufficient bandwidth to support other popular Internet applications, such as web browsing, e-mail, texting, and shopping. An IFC system designed with the end-users in mind would benefit not only the passengers, but also the airlines and IFC service providers, as shown in Figure 1 below.
Affordable IFC that enables video streaming and the favored applications of younger passengers makes for happy passengers, which tend to be loyal customers: good for passengers, airlines and IFC service providers.
To implement an IFC service that airline passengers desire, it is important to take into account the bandwidth requirements for an individual video streamer, which is dependent on the device being used; data rates are lower for smaller screens than for large HDTVs.
Netflix and Amazon Prime permit their customers to download movies and TV programs to a smartphone or tablet for later viewing. Table 1 below contains a sample of some of the programs that are available, the size of the associated video file, the duration of the video program, and the data rate associated with the program. The programs listed in the table were downloaded to an Apple iPad.
Table 1 shows that an episode of “Better Call Saul,” available on Netflix, had file size of 245 MB (mega-bytes) and estimated program duration of 53 minutes, which works out to an average data rate of 0.62 Mbps. The average data rate was derived from:
An episode of “The Tunnel,” available for download on Amazon Prime, had a file size of 347 MB and program duration of 47 minutes, which corresponds to an average data rate of 0.98 Mbps. The average data rate for Netflix programs varied between 0.55 Mbps and 0.7 Mbps, and for Amazon Prime varied between 0.92 Mbps and 1.27 Mbps.
In addition to downloading files, we did some experimenting with video streaming to a 15” Apple MacBook Pro for various service providers, and Table 2 contains summary results. Several hours of HD movies and television programs were streamed to the MacBook Pro from Netflix, Amazon Prime, and Hulu; homemade how-to videos were streamed from YouTube. The data rate results provided in the table were obtained by looking at the volume of data that was received by an application, as indicated in the MacBook Pro’s Activity Monitor for Network activity, and the amount of time the applications were run. Average Data Rate is the amount of data that the application received divided by the duration of application operation.uration of application operation.
Returning to the original problem of how to make IFC more popular with airline passengers, we can see from Tables 1 and 2 that average data rate for an individual video streamer is about 1 Mbps. So, to provide video streaming to each passenger on a 100-seat airplane, the entire plane must be fed with a data rate of approximately 100 Mbps. Required data rate for a plane would be proportional to the number of passengers on the plane, so larger planes need a higher speed connection than smaller planes. Table 3 below contains approximate seat count estimates for a variety of Airbus and Boeing aircraft.
If the average data rate for video streaming for a passenger is 1 Mbps, then data rates of 150 and 166 Mbps would be sufficient for a (full) Airbus A320 and Boeing 737-800 airplane, respectively. These figures provide airlines and IFC service providers with an initial estimate of the data rate that must be provided to an aircraft to satisfy passengers’ IFC needs. More sophisticated traffic models may be developed to account for other Internet applications, such as web browsing, e-mail, and texting. The key is to base the capacity supplied to an aircraft on the level of demand that passengers generate.
Now that we understand the required capacity, let’s turn our attention to IFC implementations. Satellite is the most common delivery system for IFC and is used by major providers such as Panasonic, Gogo, Viasat, Thales, Inmarsat, and Global Eagle. Figure 2 depicts an overview of a satellite serving a region with multiple spot beams, each of which is represented by a colored hexagon. As a plane flies across the satellite service area, its IFC service is transitioned from one beam to an adjacent beam. A satellite may have 10s or 100s of spot beams, whose diameter may range from 100 – 800 km, and serve a region that spans 2000 km or more.
Figure 3 depicts the general concept of satellite based IFC. A gateway station for the satellite is connected the Internet, and the satellite relays signals from the gateway to an airplane terminal, and end-user devices on board the airplane connect to the terminal via Wi-Fi. A satellite beam may provide service to multiple airplanes and multiple devices on board the aircraft may connect to the airplane Wi-Fi system.
Though not as common, terrestrial based IFC systems have been deployed in the US and Europe by SmartSky, Gogo, and Inmarsat. SmartSky is implementing a system in the US that uses unlicensed spectrum in the 2.4 and 5 GHz (Wi-Fi) bands; Gogo implemented the first US nationwide IFC system for Internet access using the 800 MHz band; and Inmarsat is implementing a system in Europe that uses S-band.
Whether implemented with satellite spot beams or terrestrial base stations, multiple beams or base stations are required to provide IFC service across large areas, such as the US, and Figure 5 depicts a representation of the service areas of multiple satellite spot beams or multiple terrestrial base stations (the orange hexagons) imposed on an estimate of flight routes over the US. The figure shows that some satellite beams or terrestrial base stations may have more flights and be more heavily used than others.
The best IFC systems will be designed to provide sufficient capacity for a substantial number of passengers to use the Internet on an airplane for their preferred applications, including streaming video, and the most cost-effective systems are designed such that the supplied capacity in the individual service regions meets the estimated level of demand in that service region. Such a system may not provide uniform levels of capacity across its service area. Some parts of the system, for instance over busy airports, must be designed to provide high levels of capacity, as there are many airplanes in the vicinity of the busy airports, while other parts of the system, may be designed to provide low levels of capacity. Contouring the system supply to match demand should result in a cost-efficient system.
With these measures, IFC can meet its original promise: enabling a wide population to engage in activities that make them happy (or productive) at a price they are willing to pay. The price may be low enough that airlines, like Delta, are able to fulfill their desire — or perhaps customers’ desire — to offer the service for free.