Road to Nowhere

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)

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)

VNY

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)

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.

Figure 5: Load Full Approach with a transition other than
Vectors and Edit flight plan. Here, removing ELMOO (IAF)

Okay, so now that you know loading VECTORS can be a bad thing especially when needing to be linked with a STAR what can you do to mitigate this? Load the approach using a transition other then Vectors, in this case the only option is ELMOO the IAF. Then come back and edit the Flight Plan to be VNY DARTS BEVEY et al. (Figure 5) 

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!

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.