Cross Country Planning

So, you want to go someplace. It may be only 50nm away, or it may be across the country. In both cases, there are a lot of things you should consider when putting together your plan. You should be able to answer all of these questions as you make your plan

  1. What will the route be?
  2. What sort of departure would we make?
  3. What altitude(s) are desirable or necessary each direction?
  4. How long it will take?
  5. What would we need to avoid?
  6. How far out would we need to descend?
  7. What runway would we be likely to use at our destination?
  8. What pattern entry would we expect at our destination?
  9. If you couldn’t land at your destination, what might be good alternates nearby?
  10. Once we land, where are we going?

Route planning

In my ground school, route planning can be a 2 hour lecture on its own. As in many parts of flying, there are lots of ways to approach it, but many common themes. For your initial training, you will need to learn to do this manually with chart, plotter, E-6B, and paper navigation log (there are many on-line, but the Dauntless Version A is a good start). I will, however, illustrate the route selection procedure using some electronic tools for clarity sake (students must do the measurements manually and understand that the tools usually give you magnetic course initially instead of the true course you should use for calculating wind correction angles). In deciding on a route (or several route options) you look at charts, airspace, terrain, obstacles, points along the way, possible emergency landing spots, as well as weather to come up with a route.

So, let’s start with the direct route. You mark from one airport to the other and see where it lands.

You could fly this route, given the right altitudes and/or clearances and flying very precisely. I wouldn’t recommend this route however. First, it’s not realistic. You don’t take off from the middle of the airport and end up immediately on course. Second you’ll notice it comes very close to the LAX Bravo airspace that is down to 2500′ MSL There’s no reason to get that close for this trip. Let’s look at an alternative that gives us some easy checkpoints along the way and is more realistic:

This route has the following advantages:
  • It reflects more realistically what our departure looks like
  • It gets us a little further from the LAX airspace
  • It gives us a visual target for our turn (the Rose Bowl or the 210/134 intersection)
  • After the turn it follows the general route of the 101/134, giving us confirmation of where we are
  • It has check points to gauge our progress
  • It has a point that represents where we might want to start our descent to the destination
  • It is only a few miles longer than the direct route

This route can be flown at 4500′ MSL westbound, if we talk to SoCal before entering Burbank’s airspace. If we can’t or don’t want to talk to SoCal (I recommend you do talk to them), this could legally be flown at 6500′ MSL.

You could however plan for a route that uses VORs to get you there. It might look like:

This is also a valid route and is easy navigation via the VNY and CMA VORs. It has the downside that the it follows the typical jet approach route into Burbank. Flying at 4500′ westbound, you are likely to be vectored around Southwest 737s heading into Burbank (notice the jet notation on the LAX TAC in that area).

Flight Calculations

What I covered above is defining the line you would like to follow (aka a course). When you measure the course on a paper chart using a chart ruler/protractor, you get a true course (since the “grid” on the chart is aligned with true north) and distances for each leg (make sure you use the right scale). In the example above, the online tool gives me good distances, but actually give magnetic course – use that for calculation and you’ll be off by quite a bit…

In most cases, we take this true course, the winds aloft forecasts, and an estimate of our true airspeed and crank them through our E6-B to come up with ground speed, wind correction angle, and a true heading. This corrects our progress through the air for any combination of cross-wind (which we need to correct for to stay on course) and head/tail-wind (which either speeds up or slows down our progress). For true airspeed, we start with performance information in the POH, but through experience may come up with more accurate estimates for a plane we know well.

Knowing ground speed and distance for each leg allows us to calculate the time required for each leg. Knowing time allows us to take fuel burn information (also from POH or experience) and calculate our fuel usage.

With our true course, we can correct for magnetic variation (the difference between true and magnetic north poles). That value can be read from the chart (dashed magenta isogonic lines). The E6-B has a cheat sheet to show when to add or subtract, but a memory aid is “East is least” (subtract easterly variations from the true heading to get the magnetic heading). Lastly, we correct for the errors in the compass in our airplane (taking a picture of the compass correction card will help you do this at home) – we call these errors deviation. When we correct for deviation we get a “compass heading”, normally just known as a heading.

Common mistakes
  • Confusing winds aloft and surface wind. We don’t use surface (METAR/TAF) winds for our calculations – use winds aloft forecasts at nearby locations and appropriate altitudes. If you are between locations and/or altitudes, make an estimate (interpolate) of the correct value
  • Using the wrong scale for distance measurement. If you use the sectional scale when measuring a terminal chart, you’ll be off by a factor of 2.
  • Adding when you should subtract (or vice versa) on either variation or deviations. Draw a picture if you need to
  • Coming up with E6-B calculations that make no sense – you can easily tell if winds should be a left or right cross-wind and a tail or headwind. Make sure the answer you calculate agrees.
Notes:
  1. Flight instructors have a habit of changing plans on students in order to get them ready for Area of Operation VII (Navigation), Task C (Diversion) of the Practical Test Standard
  2. Many airports have “gotchas” and instructors have a habit of selecting airports to illustrate this. Take a look at the configuration of the runway and any “displaced threshold” at Camarillo. Where can we land if we are landing to the west?

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