With years of experience providing its G3000 and G5000 integrated avionics suites for new light and midsize jets, Garmin has leveraged that capability into supplemental type certificates (STCs) for suitable jet platforms in the aftermarket. Of course, Garmin’s King Air G1000 STCs have been highly successful, but few avionics manufacturers have developed modern integrated flight deck STCs with new autopilots for Part 25 airplanes. The Citation Excel/XLS is a good example of a jet that is still in production, has a loyal customer base, and has hundreds of examples flying, many with old avionics that can't be upgraded.

Garmin’s first G5000 aftermarket upgrade was for the Beechjet 400, and 57 of those have been accomplished since it was FAA approved in mid-2016. But in just two years since the approval of the Excel/XLS STC, Garmin dealers have already done 68 G5000 upgrades. And there are about 700 of these models that qualify for the upgrade, according to Garmin retrofit sales manager Dave Brown.

The G5000 avionics suite replaces the original Honeywell Primus 1000 avionics. Some Excels had Universal Avionics flight management systems (FMSs) while others, particularly those operated by NetJets, were equipped with Honeywell FMSs. The Excel/XL panels had what now seem like ancient CRT displays, while XLSs were fitted with LCDs. The only models that don’t qualify for the G5000 STC are current-production XLS+ models with Collins Pro Line 21 flight decks.

Garmin invited me to fly its G5000-equipped Excel recently, and we set up a short trip that would give me a good taste of its capabilities. We flew from New Century AirCenter (KIXD) in Olathe, Kansas, where Garmin has a flight-test facility, to Ponca City (KPNC) in Oklahoma, an airport known for the excellent Mexican food at Enrique’s Restaurant.

A feature that makes the XLS STC unique is that it not only replaces the displays and FMSs but also the autopilot, which is pretty much all of the original avionics. While a lot of weight is removed during the upgrade—old avionics are bulky and heavy—some of that has to get added back in with ballast in the nose to keep weight and balance within limits. Another unique feature of Garmin’s business aircraft avionics is that there is no FMS control display unit (CDU); instead, the FMS resides in software inside the avionics, and the pilot interface for G3000/G5000 is a touchscreen controller that is far more user friendly than a traditional FMS control display unit.

One element that is not part of this STC is the jet’s pressurization system, which remains in its original configuration instead of being controlled by the Garmin avionics. Thankfully, the STC does away with the crew alerting system (CAS) light panel and incorporates CAS messages onto the center multifunction display (MFD).

The upgrade replaces the existing avionics and autopilot with all-Garmin equipment (except for the Mid-Continent Standby Attitude Module), including three 14-inch displays (two PFDs and one MFD), two touchscreen controllers mounted in the console, two PFD controllers, and an autopilot controller fitted just below the glareshield, where the CAS panel used to be installed. Thrust reverser lights and engine fire bottle switches remain on either side of the autopilot controller.

Invisible to the pilot are the rest of the new avionics, such as the GWX 75 digital radar (12-inch antenna), remote audio panels, GPS navcom, air data computer, engine-airframe interface unit that delivers engine information to the displays, SiriusXM weather datalink, dual ADS-B transponders, and TAWS A.

Garmin also offers options for G5000 STC buyers. The Awareness & Protection Package includes synthetic vision, Surface Watch runway monitoring, underspeed protection that also adds coupled go-around capability, and Flightstream 510 wireless gateway. In addition, buyers can select options such as Jeppesen charts, radar ground-clutter suppression and turbulence detection, GRS 56 Iridium satellite phone with Garmin Connext weather, domestic FAA Data Comm capability, and, for overseas travel, FANS 1/A+ with ACARS.

Finally, the options list also offers takeoff and landing data (TOLD), Garmin’s GRS 79 AHRS (which costs less to repair than the Litef LCR-100 AHRS or replaces the obsolete Litef LCR-93, according to Garmin), GTS 8000 TCAS II, and GRA 5500 radar altimeter.

Inside the XLS

The Garmin XLS is equipped with all the above options, and the STC is a vast improvement over the original flight deck. All controls, buttons, and knobs for systems operation remain in their original locations, so those will remain familiar to Excel/XLS pilots. Those with experience flying with Garmin avionics, even without a G3000/G5000 background, will find that making the avionics do what is necessary is intuitive and easy to figure out without cracking open a pilot’s guide. Not that pilots shouldn’t study their avionics and understand them completely before taking off, but a little poking around on the touchscreen controllers and with the display buttons quickly reveals the G5000’s secrets.

(Although Garmin’s pilot guides are comprehensive and full of detail, some pilots might find it easier to study the go-to book for Garmin pilots: Max Trescott’s G3000 and G5000 Glass Cockpit Handbook.)

I climbed into the left seat next to Garmin test pilot Scott Wheeler, and he fired up the auxiliary power unit (APU), one of the features that make the XLS so popular. It was warmer than normal at KIXD, but having the APU to run the air conditioning made us quite comfortable. Before starting the engines, Wheeler plugged in our flight plan to KPNC via Wichita, requiring just a few taps on the touchscreen. He pulled up the TOLD page, which uses the local weather to calculate takeoff distance and speeds, and that was it for pre-takeoff preparation.

Starting the Pratt & Whitney PW545B turbofans isn’t completely automatic as the engines have electronic engine controls (EEC), not Fadec. All I had to do after pushing the start button, however, was advance the power lever to idle, and the rest was handled by the EEC. (The XLS+ does have Fadec.)

Garmin’s facility at KIXD is conveniently located next to the runway we would use for takeoff, and it was a short taxi to Runway 18. Once lined up, I pushed the power levers to takeoff power, the third indent in the throttle quadrant, and the 3,975-pound thrust Pratts spooled up quickly and launched us down the runway. As is normal for the XLS, I had to pull back fairly briskly on the yoke to rotate the nose, then back off a little to avoid pitching up too steeply.

I pulled the power back soon after retracting the landing gear and flaps and beginning the climb to try to stay below 200 knots; otherwise, the XLS’s two-position stabilizer can get stuck in the midst of repositioning after flaps retraction. I was a little late on pitching up and got close to 200 knots, a reminder that it’s necessary to keep trimming this jet, otherwise the pitch control gets fairly heavy.

Data Comm Demo

With the autopilot on, we climbed to FL200 for the short flight to Ponca City, using flight-level-change mode to set the climb speed to 220 knots. Once we were level, Wheeler switched on the GWX 75 radar and demonstrated the ground-clutter suppression feature, which can be turned on or off. It did a good job of removing most ground clutter, and Wheeler pointed out that once engaged it made it easier to spot weather returns.

There were some large thunderstorms west of Wichita, but they were near the range limit of the radar, so we could see only the edge of the storms on the MFD. However, it was useful to be able to overlay the radar imagery on the moving map. And we also were able to see the storms’ footprint by overlaying the SiriusXM weather radar image on the moving map, although that information is delayed and not for tactical maneuvering. The turbulence detection feature will display targets within 40 nm, but we weren’t close enough to see anything from that weather.

While en route, Wheeler sent a sign-on message via controller-pilot datalink communications (CPDLC) to Kansas City Center, letting the controllers know that we were able to communicate via CPDLC. This was my first time seeing a live, in-flight CPDLC Data Comm exchange. Although it does share some characteristics with text messaging, FAA Data Comm—the official term for en route CPDLC—isn’t quite the same.

After signing in and confirming contact with one of the three air route traffic control centers that offer en route CPDLC (Kansas City, Indianapolis, and Washington), controllers can communicate with pilots via CPDLC messaging. During our flight, this was just simple frequency changes, but it could include route changes, new altitudes, and so on.

For the frequency change, or any new message, there is an audible “ding” and the message pops up on one of the touchscreen controllers. We were told “Contact Kansas City Center 134.900,” and the message included a time stamp. The screen offered responses such as “wilco” or “standby” and Wheeler selected "wilco" then pushed the send button.

Unlike text messaging with a smartphone, CPDLC uses canned messages, and although “free texting” can be done, it’s discouraged to avoid confusion. The best part of CPDLC is that complex messages like route changes can be loaded straight into the FMS/avionics. Of course, pilots need to double-check that the correct information is loaded before accepting the altered flight plan, but it saves a lot of the writing and button pushing that is typical with radio voice communications.

During our flight, once we acknowledged the frequency change, a new message popped up, asking which radio we wanted to tune with the new frequency. Wheeler selected Com 1 active, and the new frequency automatically went to the correct Com 1 field, moving the current frequency into the standby field. This was much simpler than typing in the new frequency and helps eliminate potential keystroke error; it also reduces the amount of voice radio traffic.

After the frequency change, Wheeler did have to call the handoff controller on the radio because he wasn’t instructed to check in via CPDLC. “They’re still working that out,” he said. Although the avionics allow the pilot to make canned requests to ATC via CPDLC, Wheeler has not often seen that work. “I’ve had mixed luck getting them to answer me that way,” he said. “Usually it’s the frequency changes that they’ll play ball with you on. I’ve sent a message before, and he just calls me on the radio.”

We didn’t get to try a route change but seeing how CPDLC works was interesting, although when it is more widely deployed, it will be strange not to hear all the radio chatter.

The XLS G5000 avionics suite has all the latest Garmin bells and whistles, such as heading sync mode, which keeps the heading synchronized when turning on autopilot and in nav mode. I like the HSI map, which is like a mini-MFD and HSI, with lots of overlays available.

Ponca City Arrival

We planned a straight-in ILS approach to Runway 17 at Ponca City. Wheeler showed me how to split the screen on the PFD, then pull up the approach chart on the left third next to the two-thirds primary display. The 14-inch display is large enough to see the entire approach chart, but if needed the joystick on the touchscreen controller can be used to pan and zoom the chart. We also placed the vertical situation display on the bottom of the MFD’s moving map, then selected 3,000 feet at Pioneer VOR as a VNAV waypoint.

Wheeler plugged in the landing information, and the Garmin avionics calculated the actual landing distance as 3,144 feet, leaving us plenty of margin on the 7,201-foot runway. Our approach speed was 121 knots while the landing reference speed was 114 knots.

The controller, back on voice now, cleared us to 16,000 feet, and I switched the autopilot to vertical speed mode and set a descent rate of 1,800 fpm, pulling the power back to keep the speed below redline. Cleared to 6,000 feet as the XLS neared 10,000 feet, I managed power to slow down below the 250-knot speed limit and continued the descent. After being cleared to 3,000 feet, our magenta jet symbol crept onto the top of the approach plate on my screen and I slowed below 200 knots so we could begin deploying flaps, then the landing gear, as the glideslope indicator showed one dot above the center.

It was hazy, warm, and the gusty wind was nearly straight down the runway, which was easily visible as we trundled down the glide path. The autopilot flew perfectly smoothly while I adjusted the power levers to set the speed, and at about 400 feet agl, I switched off the autopilot and yaw damper. Keeping the G5000’s flight path marker aimed at the touchdown zone, I eased the power back and pulled the nose up just a tiny bit, and the XLS touched down relatively smoothly, aided by the trailing-link landing gear.

With a bit of reverse thrust, speed brakes actuated by Wheeler, and moderate braking, I was able to turn off by the third taxiway, leaving about 2,500 feet of margin. I probably could have stopped shorter by more aggressively applying the brakes.

The G5000 upgrade adds many modern capabilities to the Excel/XLS. At about $475,000 to $525,000, this is a significant upgrade, and installation at a Garmin dealer takes about 1,500 to 2,000 hours of labor. Buyers can also get the G5000 upgrade through the CitationPartners Excel Eagle refurbishment program. For an airframe and engine package designed to last for decades, an STC like the G5000 upgrade brings a lot of utility and value.