« Back to Full Story

Are You Ready To Copy?

  • E-Mail this Article
  • View Printable Article
  • Text size:

    • A
    • A
    • A

Revised clearances are a way of life in the IFR world. Techniques to handle them requires forethought.

Recently I flew from Northern California to an airport I’d never been to in the Los Angeles area. The flight was uneventful until about 35 minutes from the destination when I received an amendment to my clearance. Amendments aren’t unusual in or around congested Class B airspace, but with modern electronic navigators, dealing with route changes can be challenging aviating. In this article we’ll examine the amendments received and some of the ways they could be resolved.

I was using Garmin’s G1000 but consider your nav equipment and how you might have handled the problem. The original clearance was:

Cleared to Rialto (L67) via the Watsonville 2 Departure, radar vectors SNS (Salinas), V137, HESPE, L67.

After entering the route into the G1000 we were soon level at 15,000 feet on V137. Approximately five minutes before reaching AVE (Avenal) and about 40 minutes from the destination, Center revised the clearance as follows:

After AVE, Direct GMN (Gorman) LHS (Lake Hughes) V459 to intercept V186 PDZ (Paradise) Direct.

Setting The Priorities

Because of mountainous terrain the MEA on last segment of V137 is 10,700 feet, yet it’s only about 12 miles from HESPE to the 1500 foot MSL Rialto airport, so I’d expected an amended descent routing. In the revised clearance, except for the destination everything after the next waypoint (AVE) was new. This was a whole new ballgame. Immediately entering the initial change to the routing was key to being able to meet the clearance as I was due to cross AVE in four minutes.

By entering only GMN, the next waypoint after AVE, I was at least prepared to navigate the first leg of the amended clearance. If the clearance had been to change to a different airway, entering the airway and its endpoint on would have only taken a minute or so longer. If I hadn’t had time to enter any waypoints, asking for a heading to GMN, setting the heading bug, and changing to HDG mode on the auto-pilot would have provided time for reprogramming. I could also have switched to VOR navigation using either AVE or GMN.

Locating The New Route

I cleared all of the remaining waypoints through to L67 so I could start with a clean slate. I then entered LHS, which was also the entry waypoint for V459. The challenge then was to determine where V459 intercepted V186. After a cursory review of the map on my iPad I couldn’t find V186. But there is a V386 intersecting V459 so I asked Approach if I misunderstood the airway—nope. I was told there is a V186, so I followed V459 until I saw the airways intersect roughly 32 miles from LHS. It turns out if I’d simply looked further down V459 I’d have seen V186. Or, if I’d followed V386 looking for PDZ, I’d have seen that it wasn’t on that airway.

But I was so focused on locating the intersection of the two airways to complete the routing before having to navigate it that I did neither. To quote my young son, “My Bad!”

I could have used ForeFlight’s search feature to find V186—but ForeFlight displays the full airway that is being searched for and it also deletes the existing route. Truly not what you’d desire; although it’s easy enough to reload the original flight plan.

An iPad Hiccup?

As neat as the iPad is, paper sometimes work better because when the iPad’s display is zoomed out to show more map the text sometimes gets illegible, yet when the text is legible the area displayed can be relatively small. I wonder how difficult this will be with an iPad Mini? 

Finding V186 or PDZ would have been much easier with a paper chart and so I’ll carry paper Terminal Charts in the future. Planning the transition between V459 and V186, I initially thought I might switch to navigating by VORs rather than GPS. Sometimes old technology is simpler to use because it doesn’t require programming and I knew the probabilities were good for getting another amendment to my clearance.

My next thought was to continue to navigate V459 using GPS and use a VOR set to PDZ to identify V186. Then, either press DIRECT TO PDZ or switch to VOR nav to establish the flight on V186. I could even use the G1000‘s RMI-like Pointers to identify the intersection. Set a pointer to the PDZ VOR and when the head of the needle reaches the appropriate airway course, you’re there. Start the turn early to roll out on course. It turns out there’s an easier answer. At the intersection of V459 and V186 is a closed triangle indicating the intersection of the two airways. It’s named DARTS, so I entered that as the end waypoint on V459 and selected V186 as the next airway. Finally, I selected PDZ as the end-point on V186. I pondered why the clearance didn’t include the name DARTS? The reason is probably that for those navigating solely by VORs, knowing DARTS has no value.

The Approach

With an undercast covering the LA Basin, I requested the NDB GPS-A approach. Nearing PDZ I was cleared to depart PDZ on the 045 degree radial. I set the heading bug on 045 degrees as a reminder, with the plan to push the OBS button and adjust the CRS knob to 045 degrees as I crossed PDZ to proceed outbound on the radial. I could also have pressed the HDG button and then arm NAV to intercept the final approach course because it’s a short distance. I could even have changed to VOR navigation but I’d have to change back to intercept the approach course. Seconds before arriving at PDZ, I was told: “Fly heading 043 degrees to intercept the final approach course. Cleared for the GPS-A approach.”

A quick two degree adjustment to the heading bug and pressing the HDG button when crossing PDZ initiated the intercept. The approach setup options with the G1000 are to choose the approach procedure and then select the entry method, either entering at an IAF, FAF, or selecting Vectors for the approach. Even if being vectored, the best choice is usually to select the appropriate IAF transition and Load rather than Activate the approach. If you Activate it, the G1000 immediately makes the IAF the active waypoint and that isn’t necessarily the best option when being vectored. If you select Vectors, the G1000 loads an abbreviated version of the approach— often minus some intermediate waypoints. That can make for a stressful situation if you are then cleared to a waypoint that isn’t included in the Vectors profile. Loading an IAF transition is the most flexible option.

When you Load the procedure, its waypoints are appended to the end of the flight plan. Once the approach clearance has been received, either select and enable the appropriate leg or select the waypoint you’ve been cleared to and the G1000 will continue the approach. The rest of the approach was straightforward, breaking out 300 feet above the MDA and completing a circle to land on Runway 24 with a reasonably strong crosswind from 200 degrees.

Two Take-aways

First, remember that if you receive a clearance to the crossing of two airways, look for a waypoint that identifies the intersection. If there is one it simplifies programming.

Second, reroutings have to be dealt with as a matter of course and it’s important that in the middle of the semi-stressful environment that you’re able to quickly think through what needs to be done to follow an amended clearance. The more ways you can think of to resolve any single navigation requirement, the more likely you’ll be able to come up with the best solution when you receive a daunting clearance.

This article appeared in the September 2013 issue of IFR Refresher magazine.

« Back to Full Story