Monday, June 06, 2011

Is Cross-Country Flight Planning Passé?


The widespread availability of sophisticated GPS receivers, digitized aviation charts, and internet-based weather information is changing the way student pilots are learning cross-country flight planning. The introduction of new technology and techniques always raises questions: Should student pilots be taught to use paper charts, plotter, pencil, and a slide rule E6B or encouraged to switch entirely to electronic charts, calculators, GPS and computer-based weather briefings? Don’t throw out that plotter and slide rule just yet because the best approach to learning the complicated process of cross-country flight planning involves combining old school with waay cool. Here’s the first installment of a multi-part series on the revolution in VFR cross-country flight planning, written with student pilots and their instructors in mind.

Drawing the Line

One of the first steps in cross-country flight planning is to get a rough idea about the general direction and the distance involved. With a current paper chart, just plop your plotter down and draw a course line between your departure and destination airports with a pencil. Sounds easy enough until you need to plan a route that begins on one side of the chart and continues on the other side, which actually provides a good scenario for comparing paper and digital charts.

FAA VFR charts include instructions for extending a course line from one side of a chart to the other using a pencil and a spare sheet of paper, but it's a Catch 22: You determine the magnetic course by drawing a line between the two points, but you can’t draw the course line because the points are on opposite sides of the chart.



One solution is to purchase a World Aeronautical Chart (WAC), which covers a larger geographic area at a scale of 1 to 1,000,000 as opposed to the sectional chart scale of 1 to 500,000. Good luck finding a WAC anywhere but on-line. One could purchase two versions of the same sectional and piece them together, being careful to account for the 2 minutes of longitudinal overlap on each side. You could cut the Gordian Knot by using Victor airways or choosing a landmark that appears within the overlap on each side of the chart. Or you could use your current chart and an expired chart that you just happened to have saved, just don’t mix them up!

Or simply combine paper with plastic: Use a handheld GPS or any of a variety of web sites to determine the magnetic course between the two airports, then use your pencil and plotter to replicate that course. Which approach is best? That's really up to the pilot. The goal in teaching student pilots is not to preserve hallowed aviation traditions for their own sake. Whether a student is using paper or plastic or a combination of the two, the goal is for them to understand what they're doing and why they're doing it. Using a combinational approach with old and new products may actually end up teaching the student to a correlative level of knowledge.

Digitized charts provide a big, mostly seamless chart and you'd think that would make plotting a course line on a digitized chart easier, but plotting a digital course line can be less flexible and more abstract than doing it by hand with pencil and paper. EFB apps like Skycharts Pro and ForeFlight Mobile as well as online planners like FltPlan or FlightAware will draw a course line representation, but your choice of waypoints may be limited to the VFR reporting points, intersections, navigation aids, and airports contained in the application’s navigation database. Some products allow you to define your own waypoints using lat/long, but that's not terribly convenient.

VFR Sectional and Course line using FltPlan.com

Doing the Coursework

With the course drawn on a paper chart, you use your plotter to measure the true course, locate the nearest isogonic line and apply the magnetic variation shown (subtract Easterly variations, add Westerly variations) to determine the magnetic course. If your destination or departure airport has a VOR on the field, get the magnetic course from the compass rose surrounding that VOR. Either way, with a bit of care and attention will provide the magnetic course on a paper chart within ±1˚, though simple arithmetic errors can result if you’re in a rush.

Old school pilots and instructors rightly claim that never drawing a course line on a paper chart can rob student pilots of an important learning experience about Magnetic declination. Yet with the right input data, computers tend to do a faster and more accurate job with arithmetic and geometry than humans: Waypoints entered, the digital course line drawn, determining the magnetic course is a foregone conclusion. A good approach for student pilots is to plan first on paper, then check your results using a digital source.



Go the Distance

Plotters offer a variety of scales and if you mistakenly measure using the wrong scale ... you won’t be the first pilot to do so. So look carefully, choose the correct scale for your chart and line up the correct marks.

Getting the distance on a digitized chart is a forgone conclusion, but errors are still possible. You can enter the wrong waypoint or misspell the waypoint. One tipoff is a digital course line that makes a sudden, severe turn off the edge of the map you're viewing.

If the digital product you are using provides recently assigned ATC routes, remember that these are instrument flight rules (IFR) clearances and these routes may involve altitude requirements that are beyond capability of the average GA aircraft. If you will be flying IFR, remember that there may not be any recently assigned ATC routes for the departure and destination airport that you have chosen.

Some EFB apps are better than others at drawing a course line that is visible, yet doesn't obscure important information.

FFM course line obscures airway radial

SCP course line is more ... subtle


Overcoming Obstacles

With a preliminary course line drawn, consider the appropriate altitudes one could fly. You'd think that pilots would know and apply the hemispheric rule, but it's surprising how many pilots (intentionally or unintentionally) fly WAFDOF (wrong altitude for direction of flight).  Whether you remember "Odd birds fly East" or simply refer to the diagram etched into many kneeboards, do other pilots a favor: Fly the correct altitude for your magnetic course.

Minimum elevation figures are shown on VFR charts and these provide the lowest altitude that will clear the highest charted obstacle within a specific quadrangle by 300 to 400 feet. Depending on how close your route is to that highest obstruction, flying at or just above that altitude may be the safe thing to do or it may be hopelessly foolhardy. I don't know of any app that will make the assessment of a safe altitude for you: You're going to have to use your little gray cells.

Whether you are using paper or digital charts, a nifty course line that goes to your destination won't necessarily keep you clear of special use airspace. One cool feature in SkyCharts Pro is the ability to get information on special use airspace by tapping. Locate the red circle next to an MOA, prohibited, or restricted area and tap twice to get the effective times, altitudes and the frequency of the controlling agency.



ForeFlight offers a similar feature, but it requires more taps to get the same information. ForeFlight does offer a quick way to create or change course lines by tapping and dragging.



Acquire, Combine, Conquer

Paper chart adherents often claim that paper is foolproof because paper charts don’t require batteries, they can be folded and handled, and are less intimidating to pilots who may be less computer savvy. True, but paper charts have some serious disadvantages: They can be torn, damaged, lost, or hopelessly riddled with marks from previous flight planning efforts. Last, but not least, all paper charts eventually expire and become obsolete.

Even before the FAA changed the structure for chart retailers, it was often difficult to get a paper chart unless you planned ahead. With a reduced number of chart retailers, your odds of acquiring a current paper chart at the last minute from a local retailer is tantamount to winning the lottery. A chart subscription is obviously the best bet, but that’s not much help if you’re away from home on a longer trip, need an oddball chart, or you lost your chart a week before it was set to expire.

The chart retailers who remain have to deal with unsold, expired paper charts. Charts have to be printed and physically shipped which adds to the cost and carbon-loading. Old school pilots are familiar with the various paper chart subscription services available through Aeronav or a variety of on-line retailers, but they may not be up-to-speed on the various options for digital charts.

Digitized charts, whether viewed on-line or on an iPad, tablet, laptop or desktop computer can be acquired at a lower cost (some are available on-line for free), they are easy to update, and they can cover large geographic areas without folding, flipping, or ripping. There’s no physical shipping required and no paper to recycle. The disadvantages of electronic charts basically boil down to all the possible failures to which electronic devices are heir to, including screen readability in bright light, software/hardware failures, and drained batteries. There are also some problems with how digitized charts are stitched together, but that really just reflects the limitations with how the FAA generates the charts. Hopefully that process will continue to be modernized and soon we'll see seamless VFR and IFR charts become a reality.

FAA VFR charts can be downloaded to your computer as raster files for free, and a simple, free, and platform-independent solution for viewing them is Google Earth. Follow the instructions in this WikiHowTo  and overlay sectionals and terminal area charts in Google Earth. While this approach has limitations, it does offer pilots the ability to view charts for large geographic areas at little or no cost. You can even do some rudimentary flight planning activities, like determining the course and distance between airports.

Several products are available for the iPad that allow you to access VFR charts, including ForeFlight and Skycharts. The cost of these products varies from $20 per year to $80 per year or more. Like all cockpit resource management issues, one size does not fit all. Both of these apps allow you to create flight plans that will draw course lines on the digital charts and give you magnetic courses, but old school paper chart planning provides more flexibility and, dare I say it, precision.

If you are a Mac user, MacGPS Pro provides another option for importing FAA raster charts. MacGPS Pro lets you define user waypoints, integrate with an external GPS receiver, and measure distances and courses. Similar solutions probably exist for the Windows world, but not being a Windows user, well ...

Paper and Plastic

After a student pilot has been through the flight planning process a half dozen times using paper charts, it's not clear that any more learning is likely to take place by restricting them to old school planning. While I do believe that a students' primary experience should involve pencil, plotter, and paper chart, that doesn't mean they should be discouraged from branching out to the high-tech solutions once they understand flight planning basics. Looking at the strengths and weaknesses of paper and digitized charts it’s easy to conclude that the best approach is to understand and use both. Having a paper back-up strategy in flight is the prudent advice offered by the FAA’s AC on Electronic Flight Bags.

Some pilots may still resist using digitized charts for the understandable reason that they simply prefer holding a chart in their hands. Nothing wrong with that, but charting and flight planning is changing. Time waits for no one, not even old school pilots, so don't be afraid to explore and experiment.

In future installments, I'll discuss how technology is changing calculators, navigation log preparation, and in-flight diversions.

1 comment:

David Cheung said...

Bruno's tangent last week was quite inspiring, no?

It would be interesting to devise a lesson plan that revolved around XC planning using digital products alone.

I'll get right on that. ;)