by Larry Anglisano
There are two sides to every argument but in the world of higher-end airplanes, ship-based weather radar is still considered required gear; Stormscopes are often considered accessories. Lots of vintage radar systems are still in service, sporting older monochrome cockpit indicators or early color displays.
A vintage black and white radar display in an otherwise modern panel is usually the last piece of gear considered for upgrade, depending on the airplane and mission. The advent of modern, multi-color and multi-talented replacement displays for older radar systems seems to have solved the dilemma for many owners who would like to upgrade the old stuff but dont want a display that does only radar.
In this article, well address the market offerings for multi-function displays as replacement radar indicators.
But our advice up front is to query an experienced radar repair facility to determine if your existing radar guts are of sound mind and body for long-term service. Given the costs, theres no point in putting lipstick on a pig.
What You Have
Ask many owners which radar system they have and most will be clueless. If youre buying a used airplane equipped with radar gear, get a firm grasp on the service history of the radar because fixing a beat-up, barely functioning system is breathtakingly expensive.
Far too often, new owners are stuck with inoperative radar systems and learn of the problems during their first encounters with nasty weather. Chances are, when you test-flew your radar-equipped Centurion or Baron before purchase, it was a local flight and in decent weather. The test comes when you need the radar most and nothing is worse than to have the system not work right or at all.
While the newest MFDs do indeed display radar in radiant color, theyre only as good as the front end driving them, specifically the antenna system and magnetron or receiver/transmitter section.
While ship-based radar is relatively simple, most have quite a few mechanical and electronic parts that wear out and must be replaced. Know this before buying an airplane equipped with radar and/or replacing an indicator.
Any of the radar-driven MFDs will require a heading interface. The heading information thats fed to the map display ensures that the radar images overlaid on the map are in proper orientation with the actual position of the aircraft. In most cases, if the heading synchro data fails and is not supplied to the MFD, the radar capability of the MFD is useless.
So to start, youll need a reliable compass system or HSI with proper heading output to drive your MFD/radar combination. The most common general aviation heading synchro label is XYZ heading data-an analog signal that is generated by most modern HSI systems, such as the Bendix/King KCS55A and the STEC HSI system. If you arent equipped with an appropriate HSI, you can use a directional gyro that outputs bootstrap synchro and the most common and perhaps the only game in town might be the SIGMA-TEK with synchro.
If your aircraft is radar equipped and youre making the jump to an MFD with radar capability, chances are you are already HSI equipped.
Other than the heading interface, the connections between the MFD and radar system are straightforward and some manufacturers provide an interface cable appropriate for connecting the MFD to your compatible radar guts.
Since some MFDs, such as the UPSAT MX20/i-linc are physically larger than most radar screens, some panel space issues might arise. Appropriate room for cooling should be considered, so you might not have as much available space as you think.
Once youve qualified your radar guts for use with a new MFD display, the market choices are relatively few but what is available is highly capable, if not cheap.
Avidyne was the first on the block to offer a radar/MFD interface and to this day they still offer the most radar interfaces of any of the manufacturers. The Avidyne set-up is appropriate for aircraft of all sizes and types and this company leads the league in overall compatibility and flexibility.
The Avidyne model EX500 MFD is already a proven winner with its long list of standard features including integrated satellite datalink weather. Its 5.5-inch diagonal size and crisp colors make interpreting weather on this display, as well as accessing its other features, intuitive.
The display weighs 7 pounds, including mounting tray and sits 4.35-inches high in the panel. Previous model radar replacement MFDs from Avidyne required a heading converter for the synchro interface we mentioned above.
But Avidyne listened to our groans and designed the EX500 to accept analogue XYZ heading data without the need for conversion. Previously, the XYZ needed to be converted to ARINC 429 for the heading to work.
Satisfying the installation facilities is half of the game; Avidyne knows how to play it and has from the beginning. The connectors and mounting hardware for the EX500 are robust and durable and the EX500 display looks good in any application, in our view. Its set-up is intuitive, too. We were able to configure the first EX500 we installed with little reference to the manual and Avidyne can answer any questions that come up.
This process is the most important in the radar interface and the EX500s soft keys and on-screen prompts take all the guesswork out of the equation. For example, you can set the system so that on shutdown, it parks the radar at full tilt up, full tilt down, centered or in the last position.
Radar functions are on logically labeled soft keys and a simple round rotary knob controls tilt. With the integrated datalink, you can easily play the datalink NEXRAD images against the radar data with little effort-a necessity when flying in nasty weather. And as with any of these radar replacement MFDs, the enhanced colors of the radar makes interpreting weather much easier than it is with monchrome indicators.
UPSAT MX20 I/O
As we go to press, the world has learned that Garmin plans to purchase UPSAT, a sale thats supposed to be finalized in September.
Although Garmin pledges to maintain the UPSAT product line, we dont know how or if that will impact the UPSAT MX20, one of the flagship MFDs and soon-at least, we hope-to be a serious contender in the radar replacement indicator field.
Heretofore, UPSAT marketed the MX20 to its own customers and supplied a version of it called i-linc to L-3, which bought the old Goodrich line of avionics. (Confused yet?) About the only thing missing from the MX20 and L-3 i-linc display was weather radar replacement capability. But thats changing.
The MX20 I/O supports the replacement of the Honeywell RDR2000 series vertical-profile digital radar and as we go to press, weve learned that a new interface with the Bendix RDS82 series radars will be doable with the MX20 software version 5.0. This upgrade also allows interface with the WSI datalink weather system which WSI has just certified as we go to press. With a 6-inch diagonal display, a physical weight of only 3 pounds and screen with 65,000-color combinations, the MX20 I/O paints a nice picture of weather as well as terrain and obstructions, Jeppesen Chart View approach plates, WX-500 Stormscope, Skywatch and TCAD traffic data and TAWS.
Its not as versatile as the EX500 when it comes to replacing old radar gear, however. We find the MX20 and i-linc intuitive with radar functions accessed through the radar soft key. Range up/down as well as tilt are controlled with soft keys as are the rest of the RDR2000s functions.
The radar controls with these soft keys take getting used to but like anything else, this is easy once youre accustomed to the button pushing. The MX20 was once our product of the year and we still like it. We do wish there were more radar interfaces, which would benefit larger aircraft that need ship-based radar.
However, with the WSI datalink weather interface to the MX20 and i-linc, we suspect many owners of smaller aircraft will find little need for ship-based radar mainly due to budget considerations.
Well see. Well also see what Garmin plans for it. After all, Garmin owns the rights to the old Bendix/King/Narco KWX-56 radar front end and could tie it into the MX20. (Garmin says it will redo the KWX-56 as a new product, the GWX-68.)
Bendix/King has gone great guns with its integrated hazard avoidance system or IHAS. This is a modular approach to datalink weather, traffic, terrain avoidance, radar and sferics. Part of the IHAS8000 system, the KMD850 MFD replaces the display of the Honeywell RDR2000/2100 digital radar systems.
The KAC501 weather radar module-which plugs into the KMD display-allows control and display of this radar system and differentiates between the IHAS5000 (the non-radar version of the display) and IHAS8000 (radar replacement) systems. The base MFD is known as the KMD540. The KMD540 is a 5-inch diagonal color display weighing about 5.5 pounds with the KAC501 adapter card and will display WX-500 Stormscope, Skywatch and KTA870 and TCAS I traffic systems as well as Honeywell terrain systems, such as the KGP560 EGPWS system.
If equipped with the KAS503 FIS (Flight Information System) module, the display will also play the Honeywell datalink system, a real-time, ground-based weather and flight advisory system.
The mechanical installation of the KMD540 follows Bendix/King tradition, which is to say connectors, mounting hardware and accessories are rugged and communication between the radar RT (receiver/transmitter) and indicator is accomplished via ARINC. The KMD540 is, in our view, the most robust of any of the displays weve covered in this round-up. The buttons are solid and have a positive feel and the joystick command knob/pointing device is intuitive and makes menu hopping easy.
The RDR2000 radar controls are accessed via the WX function select key on the front of the unit and if the unit is connected to the WX-500 and FIS system, a submenu allows the user to select the radar functions.
The joystick pointer controls the radar tilt angle and track. Radar gain is controlled with the inner and outer control knobs, located at the bottom of the unit.
Initial calibration and set-up of the radar via the KMD540 takes focus for the installer and this is an important step-particularly the R/T calibration and radar scan set-up. We think that this set-up is easier than that required for an RDR2000 with its standard display. This is important only to the installer but set-up and calibration of any new gear can delay delivery after installation-which, in the end, trickles right down to the owner.
If you dont have room for a separate radar display and want the accuracy and situational awareness of multi-color, ship-based radar data, our first choice is the Avidyne EX500.
With its versatile radar replacement list, integrated datalink system and ease of use and installation, this system is a paradigm of what modern-day weather awareness has become and should be. Avidyne has the most experience in radar indicator replacement and it shows.
If your panel consists of a partial Honeywell IHAS set-up, the addition of the RDR2000 radar and KMD540 display is probably most appropriate. You wont get the Jeppesen Chart View, which can be added to the MX20 or i-linc, but the radar features are excellent.
Where does that leave the MX20/L3 i-linc? A good question. The MX20 is a terrific, capable MFD but versatile radar display may or may not be in its future.
We wouldnt expect Garmin to orphan such a capable box but well just have to wait and see where it goes under Garmins stewardship. We dont know enough to offer any advice.
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-Larry Anglisano is Aviation Consumers avionics editor. He works at Exxel Avionics in Hartford, Connecticut.