Sunday 30 December 2012

Flight planning on the Raspberry Pi (!)

This is not a New Year wind-up. So, please keep reading. Having bought a Raspberry Pi for my 11 year-old son for Christmas, I couldn't resist trying it out with iNavCalc for flight-planning.

If you don't know what a Raspberry Pi is (an ARM/Linux computer for $25), visit this link for an intro.

Here it is, ready  to be connected-up to my TV, ethernet hub, and USB mouse/keyboard (shown beside a $10 bill to show the scale!):

...and here's how you connect it up (image courtesy of

When you power it on, you get the unix (linux) command-prompt: almost magical breath of fresh air in this day-and-age! If you don't agree with that comment, abandon this post. It is not for you. If you do, read on...

The whole point of the Raspberry Pi is to provide a sensible "bare-bones" platform for teaching kids how to write software, uncluttered by all the fancy stuff that comes pre-packaged with a modern consumer-oriented device such as a Windows or Mac desktop, Android tablet/phone,  iPad/iPhone or other such tablet/smartphone.

In terms of programming languages, the Raspberry Pi comes with Python pre-installed, so this is the natural starting point for code-development. However, I will leave that for another day. Instead, for now I'll simply fire-up the Chromium web-browser to test out the iNavCalc web-app interface. Note: Chromium (basically a flavour of Google Chrome which is suitable for the Raspberry Pi) doesn't come pre-installed out-of-the-box on the Raspberry Pi, but it is easy to install. I first tried the Midori browser which does come pre-installed, but the GoogleMaps (used by iNavCalc) didn't seem to load correctly...

Here, then,  is the iNavCalc web-app successfully rendered on Chromium on the Raspberry Pi showing a simple straight-line sample route from EGNS (Isle of Man) to EGPF (Glasgow):

...and here is the corresponding "Get detailed PLOG" pop-up...

...and here is the response email (via Gmail, also rendered in Chromium on the Raspberry Pi)...

...demonstrating the full functionality of the iNavCalc web-app, just like on a Windows PC or iPad, etc.

Of course, this only demonstrates that the Raspberry Pi browser works as desired when rendering the FlyLogical website. But it's a start: and it gives me yet another device to use for flight-planning when all the "real" computers in the house are taken-up (for games and shopping, etc.)

On a more serious note: since I've written the iNavCalc software suite to make extensive use of web-services from the ground-up, it represents a fun and feasible challenge to build a client app (e.g., using Python)  to "consume" these web-services on the Raspberry Pi. I'll leave that for another day...and hopefully convince my 11 year-old to help me.

Wednesday 26 December 2012

Garmin 795 Flight Plans now supported

Update 18 April 2017: completely re-written iNavCalc mobile apps with streamlined command-line interface for iOS, Android, and Windows 10

Update: the desktop browser version of the iNavCalc web-app now supports import & export of gpx and fpl files, making it simple to transform between the two formats in any either direction.

Update: with Version 3.0 of the iNavCalc mobile app on Android, you can now import an ".fpl" (or ".gpx") file by clicking on the file (within the Android file-system, e.g., on the SDCARD). Export to ".gpx" (or".fpl") is still carried-out via the iNavCalc email functionality, described below.

Update: see recently-added Route Viewer which further extends the route-sharing capabilities of iNavCalc...

I have now added support for Garmin AERA 795/796 (and Garmin 1000) flight-plan files (".fpl" format) to the FlyLogical iNavCalc flight planning email- and web-apps. This allows you to conveniently import/export routes to/from your Garmin device (via the SD card) to your other software tools and devices.

Why did I do this ? Simple: because I own a Garmin 795 and find it to be a fantastic piece of kit. Far better (in terms of usability, system stability, robustness) than the iPad for use in the cockpit environment. All that was missing was a convenient means of sharing my routes with the solved. See step-by-step examples below.

Usage Example 1: Exporting a route from the Garmin 795 into iNavCalc and beyond

First create and save a route (known as a "flight plan") on the Garmin (refer to the Garmin user guide for instructions on how to do this). The screenshot below shows some example routes in my AERA 795, with the "EGQL-EGSF" route selected in the list (highlighted). We will use this in the export example.

To prepare for export, you need to save the route to the removable SD card in the Garmin (required for all data transfers to/from the Garmin). Make sure you have an SD card inserted in the device, select the desired route for export (as highlighted above, "EGQL-EGSF" in the example) then  press the menu options button on the FPL List page. You will see the following options:

Click "Export Flight Plan" (the last item in the menu). You will receive the following acknowledgement:

which confirms that the route has been successfully exported on to the SD card, under the file name "EGQL-EGSF.fpl". Click "OK", shut-down the Garmin, remove the SD card, insert it into a PC (via a built-in SD card slot or via a portable USB SD card-reader peripheral), then browse the contents of the SD card. You should see the directory list as follows:

You should see your exported route in the root (top level) of the directory-listing, as highlighted in the above screenshot.

The exported ".fpl" file  is simply an XML file, structured in accordance with Garmin's own "legacy" schema. If interested, you may open the file with a text-editor to review the contents which are human-readable and generally intelligible, but not very useful until transformed. So, the next step is to transform this ".fpl" file into a portable ".gpx" format which can then be used in wide range of third-party software tools and devices. 

The FlyLogical iNavCalc app does all the grunt work of transforming the file from ".fpl" into ".gpx". Simply prepare an email to recipient with the ".fpl" file as an attachment. The subject-line and body of the email can be left blank. The screenshot below shows such an email, ready to be sent.

Send the email. In a few seconds you will receive a response, with four attachments, as shown in screenshot below:

Three of these files are the familiar products delivered by iNavCalc's email-based flight planning calculator. Namely, the "ROUTE_....gpx" file, the "PLOG_....pdf" file, and the "MET_....pdf" file. Of specific interest to the current task is the "ROUTE_...gpx" file which is the transformation of the original ".fpl" file into the open-standard GPX format which is supported by many apps such as, for example, SkyDemon, AirNavPro, Memory-Map, as well, of course, as iNavCalc.

The fourth attachment, the "GARMIN795_...fpl" file, is a new feature in iNavCalc. It is a version of the route,  formatted in the ".fpl" format for ease-of-import to the Garmin device. More on this in the next usage example below.

Usage Example 2: Importing a route into the Garmin 795 

Now let's go the other way. Let's create a route outside the Garmin, and import it so it becomes available as a Flight Plan in the 795. For this example, I will create the route using iNavCalcs's email interface which enables you to define the waypoints in a "natural" manner rather than having to pick them from a list or from a map view (as per popular map-centric software utilities such as SkyDemonAirNavProMemory-Map, etc). Specifically, I'll use as an example, the route prepared in my previous post "Flight route-planning the old fashioned-way -- almost...". Simply specify the waypoint ICAO names and/or navaid radials as desired, separated by spaces, on the email subject-line, and send to

That's it. A few seconds later, you will receive a response with the following attachments:

For present purposes, the file named "GARMIN795_...fpl" is the one of primary interest. This contains the desired route, encoded in Garmin's ".fpl" format. Simply download the attachment from the email, and save it in the root (top level) location on the Garmin SD card ( via a built-in SD Card slot on your PC or via a portable USB SD card-reader peripheral), as highlighted in the screenshot below:

Now insert the SD Card into the Garmin, power it on, go to "FPL List", select the options menu, and you should see the following list (from before):

Click "Import Flight Plans" (the second-last item in the menu). You will be presented with a list of  ".fpl" files available on the SD card, as follows:

Select the desired entry, in this case the "GARMIN795_a0aa2........fpl". The route will be imported. If successful, you will receive the following acknowledgement:

where, in this case, the route has been imported under the title "EGPK-EGQL 1". Click "OK", then return to the "FPL List". You will see your imported route in the list, in this case under the heading "EGPK-EGQL 1", highlighted in the screenshot:

Now click on the entry, and you will see the route in the 795 ! Job done !...

Implementation Notes

When iNavCalc carries out the conversion from of  the ".gpx" file to the ".fpl" file format:
  • All blank spaces and non-alphanumeric characters are removed from the waypoint names since these would cause those waypoints to be omitted during the Garmin import process. 
  • Since the ".fpl" format expects (essentially) NAME, LAT, LON, TYPE and COUNTRY for each waypoint, but the ".gpx" (in it's minimal, most general version) specifies (essentially) only NAME, LAT, LON, then iNavCalc  attempts to "back fill" the missing TYPE and COUNTRY fields via the following matching algorithm:
    • A search is made against iNavCalc's internal database looking for the geographically nearest entry which has the same NAME as the waypoint in question.
    • If a match is found, then the TYPE and COUNTRY are taken from the iNavCalc database, Note: the TYPE is mapped to those supported by the Garmin ".fpl" schema, namely: "AIRPORT", "VOR", "NDB", "USER WAYPOINT", "INT", which is a subset of the categories available in the iNavCalc's internal database.
    • Otherwise, the TYPE is defaulted to "USER WAYPOINT" (recognized by Garmin), and a search is made against iNavCalc's internal database looking for the geographically nearest entry, regardless of NAME. The COUNTRY of the result of the search is used. 
During the ".fpl" importation process carried out by the Garmin device, the following rules apply:
  • If a waypoint from the ".fpl" file happens to share NAME, TYPE, and COUNTRY with a waypoint already present in the Garmin devices's internal database, then the Garmin internal LAT and LON take precedence over those passed-in via the ".fpl" file. In this way, the location of waypoints in the Garmin internal database are unaffected by any alternative values passed-in for the same waypoint identifier.
  • If a waypoint from the ".fpl" file is not recognized as a pre-existing entry in the Garmin devices's internal database, then a new waypoint with given NAME (and of type "USER WAYPOINT") is created on the device. This waypoint thereafter automatically appears in "User WPT" listing.


I've successfully tested the functionality described above on a Garmin AERA 795 with software version 3.0.0 (since this is the device/version I own). I have not tested on any other device or version (e.g., Garmin AERA 796, Garmin 1000 etc), but as long as the same ".fpl" format is supported via SD card media (which I understand to be the case for the Garmin AERA 796 and Garmin 1000), then it should all work fine. If you happen to try on other such devices, please let me know how it works out, and I will update this post to reflect those experiences, accordingly.


By making use of this functionality on your Garmin device, you do so at your own risk. FlyLogical assumes no responsibility, either with regard to the functionality of your Garmin device, or with your usage of the information generated via FlyLogical.

Saturday 22 September 2012

Greetings, SkyVector !

Update 18 April 2017: completely re-written iNavCalc mobile apps with streamlined command-line interface for iOS, Android, and Windows 10

Update 23 September 2015: now supports the recently-modified SkyVector URL (exported link) format

Update 15 March 2014: iNavCalc: a complete nav planning solution for SkyVector

Update: iNavCalc V3.0 mobile app now released

Update: iNavCalc now includes NAVCOM frequencies

Update: iNavCalc now includes NOTAMs

Update: related, see recently-added Route Viewer which further extends the route-sharing capabilities of iNavCalc...

Always on the lookout for fun flying apps, I recently came across SkyVector . This is a very cool, free, web-based application which provides vectorised aviation charts with global coverage. You can define your own route via a simple waypoint entry dialog. At present, there is no flight-planning capability beyond the basic route-entry. However, you can simply copy-and-paste the list of waypoints from the SkyVector dialog into the subject-line of an email and send it to . A few seconds later you will receive a full VFR nav plan by email (click here for an introduction to this free service, and here for a detailed example).

Here's a worked example...

First open the SkyVector web-page (I used Chrome on a Windows 7 PC, in this example). Then specify your desired route as a sequence of space-separated waypoint identifiers in the Flight Plan dialog. In this example, I've specified the route from Newcastle airport (EGNT) to Isle of Man airport (EGNS) via Carlisle airport (EGNC) and the Dean's Cross VOR (DCS):

Press "Add". This will produce the following route in SkyVector:

To generate your Pilot's nav LOG (PLOG) -- including automated wind & weather, magnetic deviation, sunlight etc, copy-and-paste the list of waypoints into the subject-line of an email and send it to

In a few seconds you will receive an email with your PLOG as an attached PDF file. Here's the first two pages of the PLOG you will receive:

That's all there is to it !

Click here for another detailed example of using our free email nav planning service.

Enjoy !

A trip to Garmin's Toy Shop...

I was in Chicago on business a couple of weeks ago and happened upon the Garmin store. It's on the corner of Michigan and Erie...

What a fine place. The upstairs is best: full of aviation kit on display....

Knowledgeable and friendly staff. Took the time to describe and demonstrate all the devices I cared to look at.  As a result, I am now the happy owner of a 795...

A rock-solid unit, tons of features. Helped me through some nasty weather on the way back from Leuchars airshow last weekend. Perfect size. Fits tidily in my Bulldog cockpit via the versatile hefty clamp supplied in the box. Goodbye iPad (at least as a moving-map)...

Tuesday 18 September 2012

Bulldogs and Red Arrows in Newcastle

When we arrived at Newcastle (EGNT) on 16 September due to weather diversion from Leuchars, we taxied-in and parked adjacent to the Red Arrows, who also happened to be there overnight (following their display at The Great Northern Run)...

Video of Bulldog return flight from Leuchars

Video clip of Bulldog (G-BZFN) return flight from RAF Leuchars on 17 September 2012. I actually departed Leuchars on 16th, but had to make a weather diversion with overnight stop at Newcastle (EGNT). The next morning, I completed the return home (EGNS) from EGNT. This clip shows the cruise over the Irish Sea  at 10,200 feet with the Isle of Man just visible on the horizon...

Bulldogs at Leuchars

Our Bulldogs (G-BZFN aka XX667 and G-WINI aka XX546) on static display at RAF Leuchars Airshow, 15 September 2012.

Sunday 2 September 2012

Programming routes into SkyDemon and AirNavPro on the iPad via email

In my previous post, I described the main steps I follow when planning a VFR flight. As an example, I planned my upcoming route from Prestwick to RAF Leuchars where I'll be exhibiting my Bulldog on the static display in the 2012 Airshow.

In my VFR flight planning, I use a mix of "the old" (map, ruler, etc) and "the new" (automated PLOG computation via iNavCalc, plus other internet resources for NOTAMs, etc., all accessed via my Samsung Galaxy S2 smartphone).

A notable omission from that post was the use of my iPad in the cockpit. I'll cover that topic now.

Like most private pilots these days, I use my GPS device as my primary nav reference on-board. Specifically, I use my (IFR-approved) Garmin GNS 430. Owing to the inconvenience of programming non-standard waypoints on this device, I tend to use the "Direct-To" function between successive major (standard) waypoints to monitor the progress of the flight, and mostly to ensure I avoid controlled airspace. Even when monitoring progress on the Garmin 430,  I fly the nominal headings as prescribed by my pre-planned PLOG (see STEP 2 in previous post), making ad hoc corrections for wind (that differs from the forecast in the PLOG), and making routine visual reference to my physical chart (line on map, STEP 1 in previous post). I also routinely look out the window for the corresponding relevant ground features (it is VFR, after all).

That said, there are some powerful, feature-rich VFR flying apps available on the iPad. Notably, SkyDemon and AirNavPro, which are two of the most popular apps (at least here in the UK and Europe).

...but first, a couple of caveats

 I do not use the iPad as a primary nav reference in-flight, owing to the fundamental lack of robustness of the iPad (very much a consumer media device, not a true avionics device). I do, however, use the iPad flying apps for specific functionality that is very handy but not absolutely essential i.e., I can continue flying my route even if my iPad falls over (as it tends to do, every so often).

Also, a non-insignificant consideration is that there is simply no room in my Bulldog cockpit to accommodate my iPad in permanent view throughout the flight. Instead, I have to store it between the seats and take it out to view on occasion. 

What I use SkyDemon for

I use SkyDemon on my iPad for the following:
  • Getting a list of frequencies for my route when I'm confident I will not require any IFR materials (in which case, I use full JeppView trip-kits). Although I find the SkyDemon export to be slightly clunky (since it does not render directly in PDF format), it is more convenient than JeppView for quickly retrieving a list of comms frequencies for purely VFR purposesI do not use SkyDemon for airfield plates since it provides only the relatively crude AIP files.
  • Vertical nav sanity-checking. The "virtual radar" function is visually slick, and helps me to verify that my planned altitudes do, in fact, avoid CAS and terrain, as intended. 
  • A backup GPS-enabled moving-map when in-flight. I basically "play" with this in-flight, but do not rely on it due to the fundamental non-robustness of the iPad. That said, SkyDemon helped me considerably on my recent flight from EGNS to EGPK (see opening paragraph to previous blog post) when Prestwick approach asked me to "report Dalrymple". I couldn't find "Dalrymple" on my physical chart, it wasn't on my Garmin 430, but it was on the SkyDemon map, so I quickly adjusted my heading and flew direct to Dalrymple using the SkyDemon moving-map.

What I use AirNavPro for

I use AirNavPro on my iPad for the following:
  • A backup GPS-enabled  moving-map when in-flight. Again, I just "play" with this in-flight, but do not rely on it due to the fundamental non-robustness of the iPad. However, because AirNavPro incorporates the UK CAA 1:500k charts, I find it helpful for increasing situational awareness since I can quickly compare "one-to-one" with my identical physical chart. I somehow find this more natural than the SkyDemon vectorised charts (visually very attractive and appealling, as they are). That said,  AirNavPro wouldn't have helped me in locating Dalrymple !

Loading routes on to the iPad

Assuming I've already generated my route via iNavCalc's email interface, I will have received an email with the following attachments (as described in detail in the previous post, repeated here for convenience):

In the previous post, I described in detail the "PLOG_....pdf" and the "MET_...pdf" attachments. I'll now describe the "ROUTE_....gpx" attachment. 

As the filename suggest, this is just an XML file (in the open-standard GPX format) which encodes the route.  It is almost trivial to load this file into the iPad using either SkyDemon or AirNavPro. Here's how:

Within the iPad email app, click on the "ROUTE_....gpx" attachment. The GPX content will be displayed in the main window (human-readable XML script), and, moreover, can be "opened in" any supporting installed app (as per the usual iPad functionality for embedded email attachments), as shown below:

Selecting SkyDemon, will load the route as follows:

Likewise, selecting AirNavPro, will load the route as follows:

That's really all there is to it !

In summary

So, to recap from the start of the previous post to the present:

Starting with a simple iNavCalc email:

I can construct an entire route based on a list of waypoints (specified in a natural manner i.e., reading-off from the line I've drawn on my paper chart), then import the route in to my chosen (GPX-compliant) iPad flying apps in a couple of clicks. Viewed in this way, iNavCalc can be considered as a natural, efficient, shorthand way of creating routes for your favourite iPad flying apps. 

Leuchars airshow, here we come !

Flight route-planning the old-fashioned way -- almost...

Update 18 April 2017: completely re-written iNavCalc mobile apps with streamlined command-line interface for iOS, Android, and Windows 10

Update: iNavCalc V3.0 mobile app now released

Update: iNavCalc now includes NAVCOM frequencies

Update: iNavCalc now includes NOTAMs

Update: all described functionality now available via mobile app...

First, a big thank you to Prestwick Flight Centre for looking after our Bulldogs in the lead-up to the RAF Leuchars airshow where we will proudly exhibit them in the static display. We positioned the aircraft at Prestwick in August so we can maximize our chances of actually getting to Leuchars on 14 September 2012, given the vagaries of the British autumn weather (EGPK being considerably closer to EGQL than either of our home bases EGNS and EGSF).

I now need to plan the (VFR) route from Prestwick to Leuchars. I'm going to use a mix of old and new technologies, demonstrating the power of iNavCalc (and it's interoperability with other apps) along the way. Here goes...

STEP 1: Draw a line on the map 

Call me old-fashioned, but I find the very best way of panning a route is to have the physical chart spread out on the table in front of me. In this case, the UK CAA 1:500k chart for Scotland. Also, I will need this the ultimate nav reference in the cockpit, in case the GPS fails or gets messed-up by jamming trials (an albeit rare but nevertheless possible occurrence). In case the weather is sub-optimal, I want a reasonably direct route which avoids Glasgow and Edinburgh Controlled airspace, avoids the most significant terrain, and which gives me some practical diversion opportunities along the way -- just in-case the weather closes-in. Inspecting the map, here's the set of waypoints I've come up with.

Navaid Altitude
1 EGPK (departure)
2 Road junction, south of Kilmarnock GOW188/16 2000
3 Strathaven microlight strip GOW139/16 2500
4 EGPG (overfly) 2500
5 Road junction west of Dunblane PTH237/26 2500
6 EGPT (overfly) 2500
7 EGQL (destination)

Importantly, I've included the radial(magnetic)/range(nm) of each waypoint from an appropriate radio navaid: again, in-case the GPS fails. I simply eyeball these from the chart using a protractor and a ruler (the CAA chart conveniently has magnetic compass-roses centred on each VOR, making the task of eyeballing the radials very simple). I've also shown nominal altitudes (in feet) which avoid CAS and terrain, again, derived from inspecting the chart.

STEP 2: Generate a PLOG ("Pilot's navigation LOG")

Let's recap. So far, I've used very old technology (map, ruler, protractor). With these, I've got a sensible route drawn on the chart which I will use in the cockpit as an essential nav reference if my GPS and radio navaids fail. I now want a PLOG which I can print out and use in the cockpit to monitor my progress with regards time, fuel (primarily) and diversion-planning. I will also use this PLOG (in combination with a stopwatch and chart) as my primary nav reference in the event that my GPS and navaids fail.

Rather than doing the calculations by hand (the old-fashioned way with whizzy-wheel etc), it is appropriate to now switch to using new technology. Nothing very fancy, however -- just my Samsung S2 Galaxy Android smartphone equipped with email. No other apps required.

Specifically, I now send the following email (via my smartphone):

You can see that I've simply specified the waypoint ICAO names and/or navaid radials from the above list, separated by spaces, on the email subject-line (i.e., Subject: EGPK GOW188/16 GOW139/16 EGPG PTH237/26 EGPT EGQL). That's it. A few seconds later, I receive the following response with the following attachments:

The first of these file attachments (named "ROUTE_..."), I'll discuss later. Let's focus on the second (named "PLOG_...") which contains the desired PLOG (our goal in this step of the planning). I'll extract and describe the pertinent sections from the PLOG PDF document below.

The first section is the FLIGHT SUMMARY, shown below:

This contains the key information summarising the flight at-a-glance. Importantly, it shows that as long as I depart on full tanks (32 UK gallons in my Bulldog), I will have plenty of margin (approximately 3 hours / 250 nm) in case I need to divert. It also shows that the expected flight time is 48 mins. Given that RAF Leuchars has specified a precise arrival slot time (12:20 local), this suggests I should aim to depart Prestwick at 11:20 local, giving 10 minutes margin (can always hold for 10 minutes if I arrive early).

The next section in the PLOG PDF doc is the NAVIGATION page, as shown below:

This contains the essential navigation information required for conducting the flight (headings, timings, fuel consumption for each leg). This would be essential for continuing to fly the route in the event of failure of GPS or navaids. Winds aloft are automatically retrieved from internet-based forecasts (valid at the point in time when the PLOG email was sent) and accounted for in the heading computations. Also, importantly, the "ETA/ATA" column has space for writing in (by hand) the actual times observed in flight so that the ETA's can be updated accordingly. Finally, the "Diversion available" column gives the (still air) range and endurance available from each waypoint along the route, should it be necessary to consider a diversion at any point along the way.

The next section in the PLOG PDF doc is the WAYPOINT DETAILS section, as shown below.

This contains the coordinates (latitude and longitude) of each waypoint, expressed in all common formats. This is useful for transcribing the non-standard waypoints into a built-in GPS device such as my Garmin GNS 430 (which, being IFR-rated, does not permit automated electronic upload of user data). Also displayed is the magnetic variation at each location.

The next section in the PLOG PDF doc is the ALTIMETRY section, as shown below.

This shows the QNH (and QFE) computed for each waypoint location, computed via MET reports automatically retrieved from the internet (valid at the point in time when the PLOG email is sent). Importantly, the "Freezing altitude" column shows the (approximate) altitude when the outside-air-temperature  drops to zero degrees centigrade. The lower half of the page contains the TRANSITION LEVEL computations (note: requires the user to specify the appropriate transition altitudes along the route, defaults to 3000ft if not explicitly specified).

The next section in the PLOG PDF doc is the PERFORMANCE section, as shown below.

This shows density altitudes (at ground level and at flight altitude) computed for each waypoint location,  using data from MET reports automatically retrieved from the internet (valid at the point in time when the PLOG email is sent). This is useful for assessing the expected engine performance (especially important for takeoff and climbs). The lower half of the page shows the TAS (and Mach Number) along the route (for the user-specified IAS) computed for each waypoint location, using data from MET reports automatically retrieved from the internet (valid at the point in time when the PLOG email is sent).

The next and final section in the PLOG PDF doc is the SUNLIGHT section, as shown below.

This shows the sun position along the route, useful for determining if the given part of the route is in daylight or darkness. If daylight, the sun direction (as viewed from the cockpit) is shown, enabling the assessment of the potential for glare (and thus preparing for the associated hazards). The computations are based on the user-specified departure date/time (defaults to the point in time when the PLOG email is sent, if unspecified). The lower half of the page shows the sunrise, sunset, and hours-of-daylight for the date of the flight, computed for each point along the route.

STEP 3: Check the weather

Now let's turn to the third of the email file attachments (named "MET_..."). This is a PDF document containing the TAFs and METARS along the route, automatically retrieved from the internet, as shown below.

You can see that the MET stations in the report are automatically chosen based on their proximity to the route. There is no need to manually specify them.

STEP 4: Save the route 

Since I am pre-planning this route a couple of weeks before the date of the actual flight (on 14 September 2012), I want to save it so I can recall it on the day, and, more importantly re-compute based on the then-current weather.

It is simple to save the route in the FlyLogical database by sending an email as follows:

Note that the route specified in the previous email will be remembered (since I haven't updated it with a subsequent PLOG email request with different waypoints in the meantime). Now I am simply requesting that this previously-defined route gets saved in the database under the name "PRESTWICK TO LEUCHARS VIA PERTH". A few seconds later I received the following response:

The URL contained in the email ( ) is a link to the saved route in the FlyLogical database. 

STEP 5: Re-compute PLOG on the day of flight

Let's recap. So far, the only actions I've taken were to (i) draw my desired route on my map; (ii) send a simple email to create a PLOG based on my desired waypoints; (iii) send a follow-up email requesting to save the route to the FlyLogical database for later use. Everything else has been done for me by the iNavCalc servers.

Now let's imagine we fast-forward to the 14 September 2012, the day of my flight to Leuchars. I want to re-compute my PLOG given current weather. To do so, I could simply carry out STEP 2 again (i.e., re-specify the waypoints on the email subject-line).
Alternatively, I can retrieve the previous email response and click on the link ( ) to open the iNavCalc web-app (in the web browser on my smartphone, iPad, or PC etc), and load the previously-saved route into the GoogleMap interface, as shown below:

Opening the "Route" tab (left-hand-side) and clicking the "Get detailed PLOG..." button, opens a window from which the re-computation of the PLOG can be triggered, as follows:

Clicking the "Get PLOG by email" button will generate a PLOG delivered by email, as in STEP 2. 

The "PLOG_....pdf" (and "MET_....pdf", though less-compelling) file(s) from the email attachment can be printed-out for carrying on-board. I can also archive them on my smartphone (and/or iPad). Note: I find the Kindle app (from Amazon) to be particularly good for this, on both my Android phone and my iPad. I can simply email the PDF files to my Amazon Kindle account, then sync them to my portable devices, free-of-charge since the files are already in PDF format and do not need to be converted (for which Amazon would charge a small fee). I also use this approach for other PDF documents such as checklists, approach plates, airfield plates,  and whatever other useful references I wish to carry along without having to carry piles of paper.

STEP 6: Comms frequencies, airfield plates, approach plates

Now that I have my route and PLOG computations ready for flight, I need the list of relevant comms frequencies (radios and navaids), airfield plates, and approach plates (in case I find myself  in IMC and have to carry out an IFR approach). In my opinion, the best and most comprehensive source for these is Jeppesen JepView since they provide complete VFR and IFR coverage. I therefore prepare a Jeppesen trip-pack for the route, print it out "as PDF"  (using the excellent and free  Bullzip PDF printer app), and archive it (via the Kindle app) on my smartphone and iPad. I also take a physical printout of these just in case. However, I also have all the relevant frequencies within easy reach via my Garmin 430. They are also printed on the UK CAA chart. So, plenty of redundancy in this regard.


My favourite source of NOTAMs for the UK is via the website, a sample screenshot as shown below.

The reason I find this so useful is that it provides an at-a-glance view of the whole country, and I can zoom-in on the areas of interest, not just my nominal route. The SkyDemon iPad app (more on this in a later post) also has a powerful (and visually slick) NOTAM facility, but it is limited to the route in question, and it is therefore not very convenient for gaining a general overview e.g., when considering diversion pre-planning, etc.

STEP 8: Load route on to iPad

See my next post which covers this topic.

Saturday 1 September 2012

VFR flight plans: are they worth filing ?

I recently posted this very question on the PPRuNe pliots' forum. Here's the thread. Bottom line seems to be that VFR Flight Plans are not considered very useful in the UK, but may be better elsewhere. Then again, given the ease with which they can be filed nowadays (e.g., ), probably worth doing. You never know, might be a useful 'get out of jail'...

Friday 17 August 2012

From wherever to Timbuktu....

Ever wondered where Timbuktu is, and how far it would take you to fly there from your home base ? Simply send an email to  with the following subject-line:

EGNS Timbuktu

For example, via gmail

...and you will receive a PLOG with all the associated navigation route calculations  (as long as you have previously registered your email address with I've used EGNS (Ronaldsway, Isle of Man) as my starting point since this is my home base, but you would specify whatever you like. The distance for me would be 2244 nm, and would take me 20 hours 56 minutes flying time in my Scottish Aviation Bulldog, requiring 6 fuel stops.

This (meant to be a fun) example demonstrates the combination of the latest powerful updates to iNavCalc. Namely, (i) the further-simplified email subject-line parser; and (ii) the addition of a global aviation waypoints database (courtesy of which conveniently happens to include GATB (Timbuktu airport in Mali, Africa!).