Thursday, November 24, 2011

Jepp, Aeronav and You

Active instrument instructors are frequently asked by their students, "Should I use Jeppesen charts or Aeronav charts?" The easy answer for career-oriented pilots is to use Jeppesen because that's probably what you'll be using once you land your dream flying job. For non-career pilots, the cost-effective answer is Aeronav (at least for the time being). It's fascinating to see pilots become attached to one brand of chart or the other in a Chevy/Ford, Honda/Toyota sort of way. Instrument instructors should ideally be adept at using both types of charts, but even non-instructor pilots may find themselves confronted with a brand of chart with which they aren't accustomed to seeing. Here's an overview of just how different Jepp and Aeronav are, the advantages each has to offer, and some tips for moving back and forth between the two formats.

Name and Version

All approach charts start to look alike when you're tired or stressed, so before briefing an approach it's a good idea to first verify the name and version. Both Jepp and Aeronav put the approach name in the upper right corner, but Aeronav also puts the same information in the lower right corner. Jepp puts the city/state in the upper left corner while Aeronav uses the upper and lower right corners. Locating the city and state on a chart may seem unimportant, but it's a surefire way to be sure you have the right chart given the tradition of assigning multiple names to an airport (e.g. John Wayne/Santa Ana/Orange County or Charles M. Shultz/Sonoma County/Santa Rosa).

Jeppesen Naming Conventions

Aeronav Naming Conventions

The airport identifier on Jepp charts is in the upper left corner and includes both the FAA and ICAO format. Aeronav charts show the same information (sans the ICAO identifier) in the right corner. Aeronav really needs to standardize on ICAO format for airports: It would certainly remove the common confusion between GPS waypoints representing an airport and those representing a VOR with the same name as the airport.

Flying an approach with an out-of-date chart is ... well, stupid. Jepp puts the revision and an optional effective date on the top of the chart in day-month-year format. This is inherently problematic because by themselves, these dates are meaningless. They tell you when the chart you are reading became effective, but they don't tell you if a more current version is available. The assumption is that you've applied any Jepp updates that have been released and while this works fine for electronic charts, you know what happens when you assume ... Jepp also has a proprietary indexing schema that you can memorize if you wish and they may put an amendment number on the lower left edge and the reason for the revision at the bottom of the plate. This stuff may be interesting, but it doesn't really answer the question "Is this chart the current one?"

Jepp Revision and Effective Dates

Aeronav prints a valid date range for the chart on both the left and right edge of the plan view. If today's date isn't in the range shown on the chart, the chart is out of date. Simple, straightforward, and (dare I say it?) fool proof.

Aeronav Valid Dates

Briefing Information

The BriefingStrip™ was a Jeppesen innovation designed to provide the essential information for the approach in a consistent format. Many pilots begin briefing an approach by reading this strip, though I find this technique can overlook some important information. A few years back, the Aeronav (nee NACO) folks began incorporating a similar feature they named Pilot Briefing Information. Whether you call them strips or information, they mostly contain the same stuff in a slightly different order.

Jepp Briefing Strip™
Aeronav Pilot Briefing Information
Jeppesen's Briefing Strip starts with the radio communication frequencies, then the WAAS channel or navaid frequency and approach course. Aeronav puts the WAAS channel or navaid frequency and the approach course first. Jepp includes the minimum altitude at the final approach fix and the minimum descent altitude or decision altitude. The missed approach descriptions are virtually identical. Aeronav charts display the minimum safe altitudes on the plan view. Jepp puts them in the briefing strip, except for RNAV approaches that have a terminal arrival area where Jepp also shows the MSA sectors on the plan view: There's not a lot of difference between the two products, until you consider the Notes section.


Jepp, being an internationally oriented product, starts the Notes section with the units used for the altimeter setting and the transition altitude (where the flight levels start). In the US this information is superfluous, but outside the US it is indeed important. Jeppesen prefixes each note with a number, which increases readability.

Jepp Notes Format

Aeronav charts add an inverse T to indicate when non-standard takeoff minima are present or to indicate that a charted departure procedure is available for the airport.

The inverse A indicates when an approach has non-standard alternate minima. And to be consistently inconsistent, the N/A suffix can be used with the inverse A to indicate that an airport is not authorized for filing as an alternate. Jepp buries the fact that the airport can't be filed as an alternate on the separate airport info page, which is also where you'll find the airport's obstacle departure procedure. Not too handy, but it kinda makes sense.

Jepp Airport Diagram, Alternate and ODP info
Aeronav may include an inverse W on RNAV approaches to indicate that WAAS NOTAM service is not available for an airport. Translation? WAAS may not be available at all times, you may only get LNAV precision, and there won't be any WAAS service NOTAM to warn you during pre-flight planning.

Consistencies between both brands of charts in the Notes include (but are not limited to):
  • Procedure is not authorized at night
  • Visibility reduction by helicopters not authorized
  • Required equipment or when simultaneous reception of two navaids is required
  • Alternate altimeter settings
  • Approach course out of alignment with runway
  • Visual glide slope and descent angle or electronic glide slope not coincident
  • Conditions under which a visual descent point is not authorized

Pilot-Controlled Lighting:
  • Jepp lists lighting limitations in the notes section
  • Aeronav depicts it with an inverse L in the communications section

Circling Restrictions:
  • Aeronav puts circling restrictions in the Notes
  • Jepp puts them in the minima section, which makes a whole lot more sense

One maddening convention both charts follow is that if a different airport's surface weather is to be used, they don't provide that ATIS, ASOS, or AWOS frequency. In an age of electronic cross-referencing, this is simply criminal.

Aeronav uses the Notes section to tell you how many feet to add to the DA or MDA when using a different altimeter setting, but Jepp courteously does the math for you in the minima section.

Jepp Circling Restrictions and Minima with Alternate Alitimeter Setting

Plan View

Both charts have a North-up plan view depicting information a pilot needs to get established on a segment of the approach. Relevant obstructions are depicted on both types of charts. Note that there seem to be some discrepancies in obstruction heights on the Jepp and Aeronav charts.

Jeppesen Plan View

The highest obstruction are designated with a bold black arrow on Jepp charts and with a bold, black dot on Aeronav charts. One advantage of Jepp charts is that the Morse code for all navaids is shown, but Aeronav just gives you the navaid identifier.

Aeronav Plan View, missing some Morse Code ...

Profile View

Once established on a segment of the approach, the profile view depicts approach fixes (waypoints) and crossing restrictions for each fix. Both charts follow the convention of showing the profile from right-to left for final approach courses between 360 and 179 degrees, otherwise the profile moves from left-to-right. Given that the English language is written from left-to-right and English is the official language of aviation, changing the flow of the profile view to fit the magnetic course has always seemed a bit strange to me. Whatever ...

Neither chart product shows the profile view to scale. Aeronav just shows a diagonal line for each segment. Aeronav depicts glide slope intercept with a lightning bolt arrow and in this example, puts the graphical depiction of the missed approach procedure in a more logical and intuitive location since it is near the graphical depiction of the missed approach point on the profile view. And for those occasions when you need to conduct a circling approach, the inset map is a very handy feature.

Aeronav Profile View and Minima Section

Jeppesen clearly depicts step-downs with a level-off. Crossing restrictions are shown above the profile line, which is much more user friendly. The graphical depiction of the missed approach is located below the profile view, which is less intuitive. And when multiple minima are possible, Jepp does a thorough job of depicting those on the profile view.

Jeppesen Profile View and Minima Section

Approach Minima

Another area where these products differ is in the minima section. Jepp clearly depicts the changes in the minima when approach lighting or other components are out-of-service. With Aeronav, you must reference the Inop Components table in the front of the approach booklet - This is a really bad arrangement and one that most GA pilots hope they seldom have to deal with. Having to locate the Inop Components table when using electronic charts is B-A-D for single-pilot operations.

Jepp provides a wider range of speeds, timing from the FAF to the MAP (if appropriate), and descent rates than the Aeronav counterpart. Jepp will also depict the approach lighting that is installed, if any.

STARs and SIDs

Minor differences exist in charted arrival and departure procedures, but they aren't that big of a deal. Jepp scores some extra points by putting crossing altitude expectations next to the fix on the plan view while Aeronav buries it in the narrative.

Airport Diagrams

Aeronav provides a single airport diagram. Jepp may provide several pages of information in addition to the airport diagram, such as low-visibility taxi routes. On the airport diagram, Jepp may include Lat/Long for various parking gates, which is helpful to airline flight crews. Both products depict Hot Spots - areas where pilots historically have become confused or where runway incursions have occurred.

Extra Cost Justified?

Jeppesen has claimed that the extra cost for their product is a result of the quality control/assurance functions they perform, but the claim seems a bit hollow given how Jepp was tardy in including current RNAV approach charts for several smaller airports in California. Most recently, Jepp published an ASOS frequency for the Rio Vista airport before it was certified. I pointed this out and they removed the ASOS from the two approach charts. Then, when the ASOS was officially put into service, Jepp was one cycle behind in adding the frequency back to the charts. On several occasions I've notified Jepp about errors in their charts, but they never told me I was part of their QA team.

For their part, Aeronav makes their share of mistakes and does some weird things, too. In the case of the Rio Vista approaches, even though the ASOS frequency is published on the chart, the notes tell you to use either the Vacaville or Concord surface weather (and of course they don't give you that frequency). I've also found errors in Aeronav charts and like the Jepp folks, they are generally very receptive to feedback. After a jet blast encounter with a wayward biz jet crew a few months back, I suggested to the Aeronav folks that the depiction of one hot spot on the Oakland airport diagram wasn't in the best location. Lo and behold, they listened and changed it!

I've said it before and I'll say it again: Jeppesen is much more expensive than Aeronav. Of course, if/when Aeronav products pricing structure is modified, this could change.

Keeping it All Straight

If you're an active instrument instructor or a pilot who needs to occasionally use both types of charts, you've got your hands full. Your best bet is to practice using both types of charts on a regular basis. And you don't need to be in a real aircraft to practice: You can fly any approach in your arm chair or in a simulator for little or no cost. It's certain that I haven't covered all the differences, advantages and disadvantages of each brand of chart product. If you think I have missed something important or have your own tips and tricks to share, I'm all ears.


JohnOCFII said...

Really nice breakdown of the two charting systems. Thanks.


Ron said...

I agree. I'll refer people here in the future when they ask that hard-to-answer question about Jepp vs. government charts.

I wonder how the FAA's elimination of free electronic charting data access will affect people's preference for one over the other...


John said...

Nice comparison. My experience has been that Jeppesen seems to have better quality control in translating the TERPS forms prepared by the specialist to an accurate representation than I find with AeroNav. Often, when a discrepancy on an AeroNav comes up, one of the first things I do is to compare it with the Jeppesen chart for the same approach. Frequently, I find the Jeppesen chart correct.

John Ewing said...


Hmm ... So you have access to the TERPs forms and compare them regularly to Aeronav and Jepp plates? Interesting ... You must work for the FAA instrument approach procedures division?

I'll cite some more examples. A few years ago the OAK ILS 27R approach was changed. The CASES outer marker at 5 DME from OAK had been the final approach fix, but the FAF was moved to a 5.5 DME fix named FITKI. Jepp depicted FITKI at 5 DME and had the wrong location for glide slope intercept. The Aeronav (then NACO) chart had it right. I emailed Jepp and they acknowledged and fixed the error.

When Jepp first introduced their VFR+GPS charts, I found three airspace depiction errors within 10 minutes of looking at the San Francisco chart.

That's not to say that Aeronav doesn't make errors: They do. As to who makes the more accurate product, I don't know of any available metric that answers that question. We certainly do know which product has a significantly higher price tag.