Wednesday, June 03, 2009

Dreaming and Paper Cuts

Apologies for the delay since my last post, but I was working on some projects that actually generate income. If more of my readers would contribute a little cah-ching using the donate button in the upper right corner, well ...

The idea of an electronic flight bag is an easy sell to anyone who has endured the agony of filing Jepp revisions, pilots who have struggled to buy charts for an area they are passing through, or those who have had to lug 30 pounds of paper on a cross-continent trip. EFB solutions are out there, but many of them cost a couple of thousand dollars just to get started and can end up costing several hundreds of dollars each year in subscriptions.

This got me, a humble flight instructor on a limited budget and a Mac aficionado, thinking (perhaps dreaming is a better word) about a low-cost, home-grown EFB. In this installment, I'll be looking at how the FAA defines EFBs, what regulations govern their use, and part of NACO's Digital Terminal Procedures Publication or d-TPP product. I'm planning for this to be an on-going topic that I'll revisit as time and budget allows because frankly, I'm committed to an electronic solution to the mess of paper charts.

As usual, the FAA has provided several disparate sources of guidance regarding the approval and use of EFBs:
  • AC 91-78: Use of Class 1 or Class 2 Electronic Flight Bag
  • AC 120-76: Guidelines for the Certification, Airworthiness, and Operational Approval of Electronic Flight Bag Computing Devices,
  • Order 8900, volume 4, chapter 15, section 1: Electronic Flight Bag Operational Authorization Process

  • The FAA divides EFBs into three types, prosaically named Class 1, Class 2, and Class 3. And no government system would be complete without a bunch of acronyms thrown in for good measure, so let's cut to the chase. A Class 1 EFB is an off-the-shelf (OTS) portable electronic device (PED) for electronically displaying charts that may or may not be connected to an aircraft power supply and sits in your lap without being attached (even temporarily) to the aircraft or the pilot. In the wrong hands, Velcro is obviously a very dangerous substance.

    Class 2 EFBs utilize a yoke mount, seat rail mount, or attach to the pilot via a kneeboard. Why the distinction between Class 1 and Class 2? Ya got me! And for completeness, Class 3 EFBs are permanently installed in the aircraft, which raises the question "How you can call a Class 3 EFB a 'flightbag' when it can't be removed from the aircraft?" While the EFB data may portable, you can't exactly stack a Boeing flight deck onto your wheeled suitcase and drag it behind you through the airport terminal.

    The above-mentioned sources state that no approval is required for Class 1 or 2 EFBs when operating under part 91. The FAA would like you to carry current charts and apparently they don't care whether those charts are printed on paper or stored and displayed electronically. Speaking of PEDs, the other relevant regulation is 14 CFR 91.21, which requires the pilot in command or operator to ensure the EFB "... will not cause interference with the navigation or communication system of the aircraft on which it is to be used."

    A complete EFB solution provides the ability to view both terminal procedures, the Airport/Facility Directory (or an equivalent), and IFR and VFR charts, but I was wondering if I could cook something up for a lower cost even if it would just allow me to display terminal procedures. Low cost is important because ideally a pilot would have access to a second EFB as a backup.

    Well the FAA's aeronautical charting division offers the Digital Terminal Procedures Publication for a fairly reasonable price of $184.60 per year or $14.20 for a one-time purchase. That's only a little more than my Jeppesen paper chart subscription for California. The main issue with d-TPP is that you get everything - all terminal procedures for the conterminous 48 states, Alaska, Hawaii, and US Territories in the Pacific and Caribbean. This just cries out for re-packaging, I'd say into six regions at the very least: Western US, Central US, Eastern US, Alaska, Hawaii & Pacific Territories, and Caribbean. Re-packaging would not only reduce the size of each product's PDF repository, it would open up the possibility of on-line purchase and download rather than having to physically ship out a DVD.

    Why would someone purchase d-TPP on DVD when they can get the same thing for free at the NACO website? The problem with the "for free" part is it requires you to have an internet connection and as of this writing, that's not practical in flight. So I snagged a one-time DVD to give it a test drive and here's what I found.

    The d-TPP DVD (try saying that fast three times) package contains a passle of PDF files, one for each terminal procedure or airport diagram, and each cleverly named in a way that encodes the name of the airport and some other data. The file naming convention allows most any computer's filesystem to access those files using one or more indicies: A poor-man's database if you will. The d-TPP package provides two mechanisms for accessing procedures; one HTML-based (using a web browser) and the other a Java-based application. This sounds pretty cool since HTML and Java should provide platform-independent solutions, but the charting division has managed to screw-up what could have been a good system. In this installment I'll just be covering the HTML interface.

    Before you get your feathers ruffled about my being a Mac user, let me just say I've programmed for a living using a bunch of different operating systems in my lifetime, including IBM 360/370/390 mainframes running VM, MVS, and UTS; Harris mini-computers; HP-UX, SunOS, and a few other versions of Unix; and various versions of Windows. Luckily I have forgotten most of these experiences and that's probably why I enjoy using a Mac. It's simple and it mostly hides the complexities of the underlying OS. I am still forced to use Windows systems on a regular basis in some situations, but I just hold my nose.

    The operating system discussion is germane because the HTML/XML implementation used in d-TPP relies on non-standard features (available only in Internet Explorer) to provide search and filtering features. It's not that NACO couldn't provide a system that would work with most any browser, they simply chose not to do so. Having just enough programmer brain cells left, I was able to quickly hack some of the XML files to provide basic look-up of procedures using Firefox and even (gasp!) Safari under MacOS X. It seems the programmers wrote the HTML/XML one way and then they (and their managers) were apparently too unmotivated or under-funded to fix it. If you don't believe it, here's a comment from their own code.

    As decided on 12/30/2003, if the user uses Netscape for this software they are not going the entire gamut of items that is possible with IE. [Aside: Although IE and Netscape both adhere to DOM, there are a few crucial differences between the two. One of them is that IE allows a loose reference to DOM elements ... The same code would work in IE also implying that to make all of this cross-browser compatible write all the code following DOM principles. As originally, none of it was written that way (everything was written using IE's looser syntax) we decided it was best not to rewrite everything from scratch. The concept of the data island is Microsoft specific, hence that brings up a really big problem ...

    A big problem indeed, but at least they documented their code. The thing is, it would be relatively simple to provide an installer that would do what I did by hand to the XML files and then there would at least be some basic cross-platform support.

    Now back to my EFB dreams. Here's what the hacked d-TPP interface looks like on my Mac.

    You can click on a state or territory, but then you get a list of all the airports for that state or territory: You can't look up a specific airport and that makes it not very usable in flight.

    The charting folks really need to provide an interoperable version that provides all the filtering or, at the very least, the ability to look up a specific airport. If you use Windows then you will have access to all the filtering functions found on-line at the NACO website, but you'll need lots of free disk space or you'll need to have the d-TPP disk loaded so you can retrieve files off the DVD.

    A problem with a Mac-based EFB mainly has to do with the form factor of your basic MacBook, but there is a solution I hope to be exploring in a future post. And I'd be remiss if I didn't mention that there is also an issue with conventional hard disk drives used in many laptops, notebook, and tablet PCs. Hard disks have moving parts and among those parts is a set of heads that sit above a disk surface that is spinning at 5400 RPM or faster. This design relies on a thin cushion of air to provide separation between the heads and the spinning disk. At altitudes above 9,000 to 10,000 feet, the air gets too thin and can result disk crashes. The solution is to use a solid-state disk drive and while these drives are available, the cost per gigabyte is much greater than with conventional disk drives. Hmm ... looks like my proposed budget just grew again.

    Some of you might observe that it would just be easier to buy a tablet PC, use commercial EFB software, and be done with it. Well that would require the use of Windows, something I'd prefer to avoid and besides, I did say I was dreaming, right?


    gmedina said...

    You might try going to the following web site where someone has already packaged all the NACO data into PDFs for each state and/or region. I hate the "one plate at time" (single PDF) approach of NACO.

    The web site also had complete PDFs of the AFDs, by state and/or region.

    I've taken all this data and placed it a ASUS netbook with an internal SSD drive and a large SD card to create my own very cheap EFB. My total cost for the hardware (running LINUX) is less than $250, and I have neat little laptop to use for flight planning in the FBO, etc.

    Email me for more details if you'd like. By the way, I LOVE your blog; I've been following you for a few years. Is your freight dog blog still accessible??

    Thanks. Gary

    Ron said...

    Interesting topic. I would think a smaller and cheaper netbook computer, with its solid-state storage, would be idea for this application. You can get those from Dell for just a couple hundred dollars. Maybe put the electronic charts on a USB stick or use that to transfer them to the netbook, and off you go.

    J said...

    The ModBook would be an interesting choice. It's available with an SSD. But definitely not cheap: $2300 with an 80GB SSD.

    John Ewing said...


    Thanks for the pointer to NACOmatic. That's a great find!

    Glad you enjoy the blog and no, the Freight Dog Tales blog is closed. I've been working on turning it into a book ...


    I know I said I was on a budget, but I'm really trying to avoid the Windoze route. Still, your suggestion sounds pretty darn cost effective.


    D'oh! You let the cat out of the bag with regard to the ModBook. I actually have a 207 MacBook that I'm thinking of having converted, which would cut the cost in half, provide a pen-based interface, could still be used with a bluetooth keyboard, and would keep me out of the Windoze arena. I need just a little more cash ...

    Come on readers, click that donate button!

    John said...

    A dell Mini9 with a dual boot windows/OSX works real well. But the Mini 9 has just been discontinued. Try for how to.

    Anonymous said...

    Sounds like you're just gearing up in preparation for the fabled apple tablet :).

    A question- sure you don't get Internet mid-flight but what's to stop you from pre-downloading the necessary charts (or geographic range of charts) beforehand? I've not been on the NACO site for a while but if the PDF files are stored in some pretty logical fashion, you could rig up some kind of automatic downloaded to grab bunches of PDFs all at once?


    Dave Starr said...

    John, you've hit upon a pretty fascinating subject here. And I can certainly see why you're leaning so hard towards the Mac platform ... I've been a relauctant Wondows guy for years who swears at least three times a week I'm going to buy a mac next time.

    But could you be ignoring another, almost made to orer candidate ... the Amazon Kindle? Especially the larger screen DX model seems also as if it were speced out for the charts/approach plate task. Thin, compact form factor, fully self contained, long battery life, outstanding screen resolution/visibility, automatic portrait/landscape screen presentation switching and native .pdf storage/display ... I don't know how many NACO .pdf's the memory capacity would translate to, but with a ~3500 full length book storage spec I am sure it can hold quite a few.

    John Ewing said...


    Thanks for the pointer to the Dell Mini 9. It looks interesting and I might be able to snag on ebay or Craigslist. Not sure the form factor would work in a plane, but the price is right.


    The Kindle DX is interesting, but my research revealed that there is no easy way to load PDFs onto it. My understanding is that you must send the PDFs in and have the converted. Perhaps converting one of the TPP and A/FD PDF bundles from would work. The Kindle display looks darn near perfect for displaying approach charts.

    Dave Starr said...

    Cheecked already, I didn't read wrongly. The Kindle DX ships with "native .pdf" support (as opposed to 'conversion support' in the standard Kindle) and the interface includes:

    USB Port: USB 2.0 (micro-USB connector) for connection to the Kindle DX power adapter or optionally to connect to a PC or Macintosh computer.

    Battery life with the 3G wirelss turned off is in the sevral weeks range, and the DX screen is larger and nicer looking it seems than the base Kindle. At $489 list it isn't exactly free, but it looks eminently usable

    gmedina said...


    It's actually VERY easy to copy PDFs onto a Kindle DX. It has native PDF support now. You connect the Kindle DX to a host computer via USB and drop-n-drop PDFs to the device. The first two Kindle devices from Amazon required that you convert the files, but NO more!!! I'm thinking about using a Kindle DX with Nacomatic and to load flight manuals and various aviation gouge.

    Jeffrey Synk said...

    In (or around) June 2008, SkyWest installed very big, cumberson EFB into a few airplanes in order to get approval by the FAA to use them. Since that time the effort has stalled because of paperwork, installation costs, and implementation.

    Until yesterday I had never been in an airplane that had them installed. It wouldn't necessary be in my way, but the smallness of the CRJ flight deck, now with a non-working EFB installed made my working area just that much smaller.

    Personally, I would like to see it in action. I understand that one of the bonuses to this particular EFB is that you can plot you taxi route and know specificially where you are at any particular airport. That might be useful when fog or snow is making it difficult to taxi and your 10-9 just isn't cutting it.

    Anyway, great article. I thought this post was very useful and insightful.

    I'll come back for future visits.

    Best regards,

    Jeffrey Synk

    Adam said...

    I've been searching for something similar for quite a while now, and do believe I'm going to end up writing it myself. My goal is something closer to an EFIS, though. The plan is to do it with libraries that already exist and are well vetted, and just write the glue. It will likely end up using a datastore powered by PostGIS, a geospatial extension to PostgreSQL. Data access and updating will be via GeoDjango and Python. The moving map portions will likely come from QGIS via a custom plugin. I've not approached the display portion, but have the backend data pieces working very well at which is a playground of sorts.

    You're not alone in the desire for a good system, and not alone in thinking there's nothing out there. My primary / development machine runs OSX, and I have all the pieces working there, though I'm pretty sure by the time I'm ready (and have built the homebuilt airplane for it to go in) it will be running on Linux, and am already running everything I have thus far there too.

    I need to get the NACO DVD you mention, but it was sold out when I looked a month or two ago. I do have the georeferenced TIFFs of sectionals the FAA makes available (at least the ones near me, will expand later once things are working).

    Anonymous said...

    About a year ago I "acquired" the source to the Java version of the TPP viewer (not trivial since they moved to Java 1.5) and got it running nicely on Linux modified with larger buttons, etc. appropriate for a tablet interface.

    I had plans to integrate enroute charts and the digital A/FD but I scrapped the project when I realized that NACO refuses to release the data in the necessary formats. A talk with the NACO director at the time revealed they are leery of digital distribution, particularly in the case of the A/FD because of the loss in revenue from their paper business. That is in part why the digital enroute charts are provided in a crippled format (scanned PDFs with no georeferencing), no meta data is available for the A/FD to make searching it reasonable, and neither of them are available on DVD. When I asked why a government agency that is funded by our tax dollars has to make money he didn't have a good answer.

    Incidentally, I discovered that NACO's Java viewer is in violation of the GPL software license since they included a GPL (not a LGPL) library and all requests for the official source code have fallen on deaf ears.


    Russ said...

    At you can get full TERP volumes for a Kindle DX. Not just the "one plate at a time" thing that gmedina mentioned above.

    Michael said...

    Hi John,
    I recieved your email about the MAC changes to my downloadplates perl script and I made the changes. New version is up for you.