Post lockdown engine blues, Rotax SMD ignition modules

mags before

Our Rotax 912UL has never started as well as it does now, but that wasn’t always the case!



Our aircraft had the post lockdown blues and so did we! The first time starting her and she would turn over, but not firing, there was simply nothing there. Others offered the normal advice, you know the normal things people say; make sure the throttle is fully closed, pull the choke fully out and run the electric pump for a couple of minutes! well yes, I had done all of that, next comes the offers to start her for me, they tried and failed too.  I remembered an article which said to warm the ignition modules with a hot air gun if you are having trouble starting. Hot air gun in hand I warm the modules for a few minutes, hastily getting back in and pressing the start button and the engine sprang into life! I warmed the engine before shutting down and putting the cowling on. Others experienced similar issues starting her over the next few flights when the engine was cold.

Then the battery gave out,  low voltage of a failing battery could cause the issue so this was probably the cause. After replacing the battery we could not start her due to the weather and the next day Gary Masters was due to do a service. Service done, it was time to do a ground run, I hit the start button and she turned over but didn’t fire! Gary came over and poured very hot water over the mags and she starts and runs perfectly. Gary then confirmed our suspicions that the Mags aka ignition modules have both failed! 


mags before


These Ducati modules have a reputation for failing and being expensive to replace, circa £1,500 a pair. In a BMAA magazine I had read of some recently approved modules from a company called Light Flight who are selling IGNITECH modules, I text the number on their website and shortly after had a phone call from a very helpful Andy Buchan. Andy told me the modules were approved for use by the BMAA and have been in use across Europe for some time. We purchased two modules with long leads and a simple bracket for £320.00 inc P&P, quite a saving, especially as they claim to be longer-lasting due to being mounted within the cockpit away from heat and vibration. The Modules have an option to boost the spark via a 12V feed taken from the starter solenoid switched positive. The boost ensures a full-strength spark at the low starting rpm. There is also a soft-start software option which we have not enabled currently as it doesn’t seem to be necessary.

Now with the new battery and the new spark boosting mags our Rotax starts effortlessly on the button. We could view it as we had to spend £320 or the way we see things is we saved £1,180!

The fitting is not difficult, but not straight forward either, as they are fitted inside the cockpit on the back of the firewall. This means drilling a hole of approximately 25mm to enable the pre-made cables to pass through, we then closed the hole by placing a piece of split pipe over the cable, thus protecting them and filling the hole. The wiring for the boost is simple, consisting of connecting 1 wire from each module to the switched solenoid terminal (Warning, ensure the battery is disconnected before connecting). 

We added a backing plate to the bracket to ensure airflow around the modules, they run warm to the touch the manufacturer says up to 50 degrees C. The 2 white blocks are voltage regulators for the supplemental supply and come with the modules pre-wired.

Would I recommend these modules? It’s early days, but with the ease of starting we now have and the fact they have a proven history in Europe, I think it’s worth the extra effort to fit these, not only because of the saving, but they have a spark boost and hopefully a longer life too!

What is EC or should I say Electronic Conspicuity or even ADS-B In and Out?


What is EC or should I say Electronic Conspicuity or even ADS-B In and Out?

And why do we care anyway!

In today’s world of aviation, technology is becoming the norm and if that helps to increase safety then I for one am in favour of it and I hope you are too.

It was not long after I got my NPPL that I was using and EC in the form of the then beta product of an upcoming technology called Pilotaware. Fast forward a number of years and Pilotaware, SkyEcho 2, Stratux, Power FLARM and more are all affordable in cockpit EC devices. Add to these the traditional transponders which have various modes A, C and S as well as ADS-B Out and some systems having ADS-B In and then there is weather reception, TCAS and secondary surveillance radar (SSR) too!

So as a member of both the UK Microlight and GA community what is best for me and what do all the TLAs (Three Letter Acronym) mean?

ADS-B stands for Automatic dependent surveillance-broadcast, for your starter (yes I know that is a four-letter acronym).

But first to set the scene, I would not consider myself an expert, but I do have some knowledge having researched the subject to enable me to write my transponder decode application which is available for free download from this site.

The short version of this blog is that I remain happy with my current combination of devices, which consist of ADS-B Out, and Pilotaware for ADS-B In and Pilotaware device reception including OGN (Open Glider Network) when near a ground station that is up-linking and all displayed on SkyDemon.


The Transponder

The transponder is a powerful device and comes with various modes depending on its age and capabilities. Older aircraft have Mode A & C with newer Aircraft/transponders having Mode S also

Mode A: In response to Mode A interrogation the transponder transmits an identity code for the aircraft in the octal range 0000-7777 the Squawk code.

Mode C: Transmits the aircraft’s pressure altitude automatically and augments mode A hence sometimes called mode A/C

Trig Transponder

Mode S: Mode S has over 17 million unique 24-bit aircraft addresses known as the ICAO number or mode S address allowing the unique identification of every aircraft, altitude reports in 25 feet increments and the call sign (or tail number) is transmitted along with other information also.

Unlike traditional Secondary Surveillance Radar (SSR) stations which elicit multiple replies containing the same information from all aircraft within their range, Mode S makes selective (Mode S is abbreviated from Mode Select) interrogations of each specific aircraft. ‘All call’ interrogations are also made to identify new aircraft to be interrogated. Mode S transponders are backward compatible with Mode A/C radars.

Civilian Mode S supports a number of different messages Each message has a particular purpose. The formats DF0, DF4, DF5, DF11, DF16, DF20, DF21 and DF24 are used in civil aviation at present.

Number Message
DF0 Short Air to Air ACAS
DF4 Surveillance (roll call) Altitude
DF5 Surveillance (roll call) IDENT Reply
DF11 Mode S Only All-Call Reply (Acq. Squitter if II=0)
DF16 Long Air to Air ACAS
Comm. B Altitude, IDENT Reply
DF24 Comm. D Extended Length Message (ELM)


Location Reporting

Now some people think as they have a mode S transponder it transmits their position and that their exact location is displayed to other aircraft, but this is not the case. Location information is transmitted in the ES (Extended Squitter) messages DF17 and DF18.


DF17 1090 Extended Squitter
DF18 1090 Extended Squitter, supplementary


For a mode S transponder to transmit ES DF17 (we will come to DF18 later) the transponder must be connected to a position source i.e. a GPS, and these come in different levels of certification from uncertified up. This configuration is known as ADS-B Out.

It is DF17 (and DF18) that devices like Pilotaware and SkyEcho use to show the exact location of other Aircraft. For non-ADS-B Out aircraft, they use the signal strength only to show proximity but, not location and they show altitude received too.

If only ADS-B Out gives the position how does Flight Radar 24 and 360Radar work their magic and show position of the other aircraft without ADS-B Out? Well, this is done by a system called MLAT which is out of scope for this blog as it requires multiple ground stations.

So DF18, this is essentially the same as DF17, however, it is the message used by a new breed of EC devices which are low power and low cost. They are regulated under CAP 1391. CAP 1391 (First published 2016) specifies Electronic Conspicuity devices that have the ability to signal their presence to other airspace users, thereby turning the “see-and-avoid” concept into “see-BE SEEN-and-avoid”.

It must be noted that CAP1391 states that they must not transmit if carried in an aircraft equipped with a Mode S transponder as this will result in mode S messages and DF 18 being broadcasted.

A system receiving DF18 implicitly knows it cannot interrogate that device, hence no aircraft can transmit DF18 if it has a mode S transponder as it will block or confuse SSRs (CAP1391 6.35). You cannot switch your mode S transponder off due to SERA.13001.

SERA.13001 requires the pilot of an aircraft equipped with a serviceable SSR (Mode S) transponder to operate the transponder at all times during flight.

Additionally, these new devices are intended for UK Annex II aircraft; non-complex EASA aircraft of <5700kg MTOM and for gliders and balloons. (CAP1391 Executive summary 7).

Lastly, they do not allow access to TMZs.



Mode S sends more information then just the location received from the location source, it sends information about how reliable that data is and if it were to fail, the size of containment that is required and more.  The data that most advertisers quote is the SIL value but, this is just one of the parameters.

Much is made of some of some of the new devices having a SIL1 GPS  in their ads, however, most have an SDA of 0 which means they are not trusted!

SIL (Source Integrity Level) field is used to define the probability of the reported horizontal position exceeding the radius of containment defined by the NIC value. 0 is unknown integrity or untrusted!

SDA (System Design Assurance) field defines the failure condition that the ADS-B system is designed to support.

NIC (Navigational Integrity Category) is reported in conjunction with the SIL, NIC of 0 is unknown integrity or untrusted!


Can I be seen on TCAS?

Yes, if you have a mode C transponder because most TCAS system utilises an aerial array to determine the position of other aircraft using mode C transmissions.

TCAS II has to be linked to a mode S transponder if fitted so its presentence is encoded in the mode S messages. But TCAS systems below version 7.1 don’t use the ADS-B out messages from other aircraft.

TCAS II Hybrid Surveillance does use Mode S messages but currently has limited adoption.

Hybrid surveillance is a method that decreases the number of Mode S surveillance interrogations made by an aircraft's TCAS II unit. This feature, new to TCAS II version 7.1, may be included as optional functionality in TCAS II units. TCAS II units equipped with hybrid surveillance use passive surveillance instead of active surveillance to track intruders that meet validation criteria and are not projected to be near-term collision threats. With active surveillance, TCAS II transmits interrogations to the intruder's transponder and the transponder replies provide range, bearing, and altitude for the intruder. With passive surveillance, position data provided by an on-board navigation source is broadcast from the intruder's Mode S (ADS-B Out) transponder. The position data is typically based on GNSS and received on own aircraft by the use of Mode S extended squitter, i.e. 1090 MHz ADS-B, also known as 1090ES. Standards for Hybrid Surveillance have been published in RTCA DO-300. The intent of hybrid surveillance is to reduce the TCAS II interrogation rate through the judicious use of validated ADS-B data provided via the Mode S extended squitter without any degradation of the safety and effectiveness of TCAS II.


What to buy?  

Should you buy a CAP 1391 device such as a SkyEcho 2? Well that’s up to you but, if you have a Mode S transponder you will need to disable the only feature it has over Pilotaware, which costs less and has mode compatibility with other systems.

If you don’t have a Mode S transponder then Yes, it is an option and will increase your visibility, but not to most TCAS equipped aircraft including military jets and helicopters as they are looking for mode C transmissions.



Finally, for me a proper transponder with ADS-B Out (certified GPS or uncertified) is also essential in the increasingly busy skies for your visibility and Pilotaware as your ADS-B In device gives you the best low-cost solution currently.

Today I was told a story of an instructor doing a PFL and they got a Mode C alert on Pilotaware but, at first could not see the other aircraft. Then at a low level saw a chinook below them. The instructor’s aircraft also had a transponder with Mode A/C and S also with ADS-B out, so the TCAS in the Chinook would have been going off too. “see-BE SEEN-and-avoid” in action.



ApproBASE Review

I got a tweet from this AviationLOGIC asking if I would review their app ApproBASE so I decided to take a look!

For more information on the app visit their website at

About the ApproBASE App
Version 1.1.1

ApproBASE Is a simple but useful app if you are new to flying or like me a student pilot about to venture away from my local field while learning navigation. It collects via a few screens you approach heading and details of the circuit you want to fly. It then generates a nice animated graphic showing you the circuit and headings, helping you to visualise the circuit removing any uncertainty.

The first page you see when ApproBASE loads is the Welcome screen which contains the disclaimer also. I understand why the disclaimer is here and why its is shown every time you run the app, however it would be nice if the “Agree” button could be hit without scrolling down!

I’m not sure I would try and use it inflight (but that’s just me!), unless I was using an iPad for navigation anyway. I would however use it to review how I intend to join a circuit I had never flown, before setting out.

This leads me to the first enhancement I would like to see, that is an option to print out the circuits for my navigation notes. Yes the wind direction may change and I might need to re plan; using the app in advance of joining, then using it in flight maybe an option I would consider.

What would make it of use for me in flight is the option of entering an airfield (or farm strip) in a directory or a favourites list by longitude and latitude and maybe the radio frequency too. When you select this airfield and enter the runway and approach direction it could display the radio frequency together with the distance and direction, allowing me to make the call that I’m X miles south (or wherever), this together with the animation on a single screen would be of great help!

The graphics are clear and the animation is simple to understand, but I’m not sure I would pay the £3.99 for ApproBASE, I would have paid 69p without thinking about or even 99p, over that I tend to want to make sure it meets a need I have and to be honest I have never thought about this or the need for an app to show me how to fly a circuit. However with the enhancements above I would  buy the app at the asking price or even a little more!

I showed ApproBASE to my instructor thinking he would say it was not necessary, but instead he said it maybe a good teaching aid, he proceeded to enter an airfield we use for out landings as follows:
Runway 27 RH, overhead join from the south, unfortunately the animation shows an approach from the north! I will feed this back to AviationLOGIC and up date this review with any response.

Currently ApproBASE is only found when you search the app store for iPhone only and not iPad, it does run on the iPad, but within the iPhone compatibility display not as a native iPad app.

If you have used this app why not let me know what you think below.