ADS-B Technology in the Electronic Flight Bag World
In the last article we looked at the important feature of displayed traffic on your EFB moving map display. This feature is designed to provide us with additional information we might not otherwise have, however it is not designed to take the place of standard “see and avoid” principles of visual flight. In this blog we go one step further to look at ADS-B technology and how a receiver can be linked to your EFB to provide a greater volume of traffic information.
In the age of EFB it is becoming more common to place too much dependence on standard traffic information. Remember the EFB traffic feature relies on mobile data plus numerous other factors such as traffic service options being toggled “ON”. By adding an ADS-B receiver to the mix and linking it wirelessly within the cockpit to your EFB device, you immediately gain a greater volume of traffic information to assist with Situational Awareness. As a matter of interest, ADS-B traffic icons appear dark blue within OzRunways when sourced from a linked ADS-B receiver, as opposed to the standard light-blue icon. This is designed to allow the user to differentiate between the source of the traffic information.
There are a number of ADS-B receivers on the market which range in price and functionality. Some allow dual-band ADS-B IN, although in countries like Australia only the single 1090MHz Frequency is used. Interestingly in the USA where data coverage is much less reliable on cross-country flights, many pilots possess a Wi-Fi only EFB device, and an ADS-B receiver which also receives meteorological information on the second 978MHz Frequency. This weather information is relayed to the EFB through Wi-Fi.
Common device options include:
- uAvionix Ping: The smallest, and most affordable receiver. Requires a power source and is applied to the windshield using a supplied suction-cup.
- Appareo Stratus 3: Has an accurate external GPS receiver, plus Gyroscopes & Accelerometers allow AHRS function and a back-up Attitude Indicator on your EFB. The most expensive of the listed units.
- SkyEcho2: With an intermediate price tag, this unit is the only one classed as an “Electronic Conspicuity Device”, meaning it can provide both ADS-B IN and OUT. It’s a 20-watt device designed to make you visible to those with ADS-B receivers. It is NOT a transponder and does not respond to SSR or TCAS interrogations. Having one does not replace the need for having at least a Mode C Transponder to access Class C airspace in a VFR Aircraft. It is also not for IFR aircraft; those must have full ADS-B out. For IFR, having a Mode-C transponder plus SkyEcho does not meet the requirement, although those flying IFR will still benefit from purchasing a receiver. The unit includes GPS and a built-in barometer used for ADS-B altitude (not useful in pressurised aircraft).
So which one should I buy?
It really depends on your use-case and budget. We recommend the Ping device for those on a budget, the Stratus 3 for aircraft already equipped with full ADS-B, and the SkyEcho2 for all VFR aircraft without ADS-B. The latter advice is simply because the SkyEcho unit allows you to see and be seen by transmitting your position, altitude, course, and speed to surrounding aircraft with an ADS-B receiver.
Some other information sources may suggest to simply use an EFB application which links itself to an “ADS-B feed” and avoid a receiver altogether. The issue with this approach is that it still depends on Mobile Data Coverage. As soon as you lose 4G due to position or altitude, no more ADS-B traffic icons will appear on your EFB. By using an ADS-B receiver in your cockpit, you overcome this limitation and will see ADS-B traffic on your EFB even at those times where no Mobile Data Coverage is present.
Stand-Alone ADS-B Applications
While we’re looking at ADS-B technology it would be rude not to discuss the technology involved with applications like Flight Radar 24 or Flight Aware. When using these applications in flight, the same dependence on Mobile-data coverage as described above exists. Both sites differ slightly in their collection of data prior to its distribution as seen by the end-user, however sources can be summarised as:
1. Network of Ground-Based ADS-B receivers (Limited to 250-450km). While coverage can be quite good for higher altitudes, to see traffic at circuit height the receiver would need to be within approximately 30nm, or preferably at the airport in question, which can limit the usefulness in the circuit. That said, see and avoid as well as a solid “Rx/Tx” should be the “go-to” in this phase of flight.
2. Satellite ADS-B pick-up
3. Multilateration (MLAT) – Mode S Transponders between 3000- 10,000ft
4. ATC Data (Flight Plan Interpolation)
Some other information sources may suggest to simply use an EFB application which links itself to an “ADS-B feed” and avoid a receiver altogether. The issue with this approach is that it still depends on Mobile Data Coverage. As soon as you lose 4G due to position or altitude, no more ADS-B traffic icons will appear on your EFB. By using an ADS-B receiver in your cockpit, you overcome this limitation and will see ADS-B traffic on your EFB even at those times where no Mobile Data Coverage is present.
A primary VFR example of where fleet-wide fit-out with ADS-B receivers would be advantageous is with the high volume of fire-fighting aircraft we see in close proximity to each other at this time of year. Guaranteed traffic information on your EFB regardless of mobile data coverage if all were equipped with a SkyEcho2 for example. That being said, a quality lookout (see & avoid), situational awareness, task prioritisation, decision-making, and of course communication all take precedence over the EFB traffic feature.
The teams at Airspace Flight Solutions & OzRunways can provide guidance right across the board with any of the above information. Visit the OzRunways website at www.ozrunways.com to purchase any of the ADS-B receivers noted, and email support@ozrunways.com or andrew@airspaceflightsolutions.com.au with any questions.
Safe Flying!