The G1000 Invisible
Route-Discontinuity Gotcha!
By Jeffrey Robert Moss “MossY”
One of the biggest gotchas in flying the Garmin G1000 occurs
when the Arrival (STAR) and Approach link up together at the same
waypoint. These scenarios commonly occur in major terminal areas at the satellite airports, which we Citation drivers tend to frequent. The procedure designers try
to design the Arrivals to terminate at or near where the approach begins in an
attempt to make the workload for the pilot and the controllers to be as minimal
as possible. That being said when it comes to avionics this can create quite a
pickle if the approach is loaded into the flight plan the wrong way.
A few weeks ago I was flying with a CJP member in his new
Mustang. We were en route to Santa Monica, CA (KSMO) to pick up the infamous Cyrus
Sigari of JetAviva on our way to the CJP regional event in Dallas. The pilot
new to arrivals (he transitioned out of a Cirrus SR22) was cleared to Santa
Monica via the Avenal Transition and the Fernando Five Arrival (AVE.FERN5) (Figure
1)
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| Figure 1: Fernando Five Arrival |
The last waypoints of the Arrival in the Flight Plan look
like this: VNY DARTS KSMO.
With the weather being reported as SCT015 the pilot elected
to the load the approach. (Figure 2) Santa Monica
interestingly enough only has one approach, a VOR-A. The reason for the –A
(Circle to Land only) is that once you cross the step down at CULVE (the twin high
rises in Century City) the final step down is too steep to allow for a
straight-in landing. Pilots can still get conduct a straight-in landing if they
make it down to MDA in time to land within the normal parameters laid down by
the regs.
 |
| Figure 2: KSMO VOR-A Approach |
Now pay attention! The pilot got into trouble by loading the
approach using the VECTORS transition. With older software versions the VECTORS-to-Final
feature would only give pilots the final approach fix (FAF) as the active
waypoint once activated. Pilots for years lobbied Garmin to give us all the
waypoints on the approach so if given a crossing restriction at an Intermediate
Fix we could elect to make that fix the active waypoint and thus have better
situational and positional awareness. Last year our wish was granted. However
the new feature has reared a new bug.
 |
| Figure 3: KSMO VOR-A approach loaded using vectors transition. Note the auto-edit deleting DARTS fromthe Arrival. |
Upon loading the approach using the VECTORS transition, the
G1000 auto-amended the flight plan to read (Figure 3)
APPROACH VOR-A
DARTS
BEVEY
CULVE
SMO
One would expect the aircraft after
VNY to sequence to DARTS BEVEY etc., right? WRONG!
The Garmin inserts a ROUTE
DISCONTINUITY after VNY. The pickle being the ROUTE DISCONTINUITY is invisible
in the flight plan. CJ pilots flying with Collins FMS3000 are aware of Route
Discontinuities because Collins inserts a ROUTE DISCONTINUITY data line in the
flight plan to warn pilots the flight plan sequence will terminate. The only
way for G1000 pilots to detect the Route Discontinuity is by doing a Map
Integrity check on the MFD. Here the pilot will notice that the thin-white
feeder line from VNY linking to DARTS is missing. (Figure 4)
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| Figure 4: KSMO VOR-A loaded using Vectors Transition. Note: after VNY there is a gap on the moving map showing no connector leg to DARTS. This is the “Invisble ROUTE-DISCONTINUITY”. |
In this scenario (loading
Vectors) the situation is compounded because the G1000 does an Auto-Amend and removes
DARTS from the Arrival. DARTS is still displayed but as the first waypoint in
the Approach sequence. So I’ll ask you this question. What will the G1000 do
when it gets VNY when the next item in the Flight Plan is a Route
Discontinuity?
The roll annunciator GPS (nav)
flashes in AMBER several times and then is replaced by ROL mode. Yes, that’s
right, ROL mode. Sorry Charlie, no more GPS/NAV mode for you! This occurs at a
very busy time during the approach as ATC will either tell you upon reaching DARTS
proceed RNAV own-navigation to BEVEY and cleared for the approach or they will issue
Radar Vectors to the final approach course. Failure to recognize the mode
change into ROL mode at this crucial moment and the pilot might find themselves
hugging the KLAX 24-R final approach course and trust me from experience ATC will
have a phone number for you to call.
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| Figure 5: Load Full Approach with a transition other than Vectors and Edit flight plan. Here, removing ELMOO (IAF) |
Loading
the full approach avoids the Invisible Route Discontinuity. (Figure 6) So next
time you have an Arrival that ends at the same waypoint as where an approach
starts raise your threat level and be sure to load the approach using a
transition other than Vectors. It will keep the leg less exciting and the
flight more enjoyable!
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| Figure 6: KSMO:FERNS5 STAR wiht VOR-A Approach loaded. Note the white connector line from VNY to DARTS. |
Jeffrey Robert Moss “MossY” is the 2010 National CFI of the
Year, Master CFI and an Instructor/Mentor Pilot on the Citation Mustang, M2 and
CJ Series. He is widely regarded as a subject matter expert on Garminology and
transitioning single-engine piston pilots directly in single-pilot jets. His
company FlyingLikeThePros.com has online video courses for pilots on the G1000
and iPad.
