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The Source Code conundrum

Updated: Mar 29, 2022


A few years ago while at a customer’s site one of our partners was asked to “take a look” at an EASA qualified A320 FTD; the device was functioning well, it was well designed and well put together. The trouble was that the manufacturer of the device had long gone into liquidation, the device was way behind the then current Airbus standard and desperately needed a new visual system/models. Logging into the host showed there was no source code on the device or the tools required to create a new load. After failing to find anyone with access to the source the partner was asked what could be done. Sadly the only way of updating it would have been to throw away the host, re-compute it and replace the interfaces to the hardware; worse, the cost of doing so would have exceeded the cost of obtaining a new device.

A sobering tale, without source code you are tied to a Flight Simulator Training Device’s (FSTD) Training Device Manufacturer (TDM) for updates. If that TDM is no longer trading and has not been subsumed into another TDM your FSTD’s usefulness may be time limited.

It used to be very different. It was not that many years ago that all FSTDs were all delivered with source code on them, indeed it was in some cases the only location where a complete load existed. However now all the TDM’s restrict or deny operators access to source code, protecting their Intellectual Property as well as that of the aircraft and avionics OEMs, thus limiting the degree of change an operator can make. This week we look at this complex issue.

Why the change?

As always there are multiple factors in play here.

Back in the day, the TDM used to produce the complete simulation, perhaps using a few stimulated as aircraft Line Replacement Units (LRU). But in the 1990s, with the advent of more advanced aircraft types, that changed. First, we had the move toward re-hosting or re-targeting of the software in these LRUs and the subsequent Integrated Modular Avionics (IMA) hosted Loadable Aircraft Software Parts (LSAP). This was closely followed by the intrusion of export controls associated with dual use technologies, first manifesting itself with controls on Electronic Engine Control (EEC) systems. Finally, the aircraft manufacturers, for various motives, restricted the contents of the data packages they license; replacing the data with their own, obligatory, simulations provided in executable form only. That is to say that even if the TDMs wanted to provide full source code they cannot, as discussed above in many cases they do not have it themselves.

We then have the issue that the world has moved to an era of Intellectual Property (IP) and Intellectual Property Rights (IPR) protection. Add the more nationalistic pose taken by some governments and the corporate ownership of some of the TDMs and again this further restricts the TDM’s ability to deliver source code.

That all said it is also extremely galling for the TDMs when they see small third party companies come along and update an FSTD that they manufactured and sold, at a low margins in many cases, denying them the lucrative updates revenue; if they can prevent this they obviously will. Restricting source code availability is, not unreasonably, one way of achieving this.

Will I be able to get it if I want to?

Yes and no. As discussed above some of the code on a modern FSTD is simply not in the TDM’s gift to give, or more accurately to sell you. But let's step back and consider why you would want the source code in the first place. We have seen that the majority of operators want the source code for one or both of two reasons. The first being to ensure that, should the TDM cease trading during the lifetime of the FSTD, they will not be stuck with an unsupportable device like the A320 FTD we know of. The second is to give them the ability to make small system changes without recourse to the TDM; particularly if they find the TDM’s proposal unreasonable .

If the motivation is to just ensure future security, the TDM will probably offer to place the source code in escrow, whereby the source code is held by a trusted third party (the escrow agent) and only released should certain predefined conditions be met; as we will see later this is not a total guarantee. For the operator that just wants to make small changes they may actually not need it anyway, increasingly the TDMs are moving to software structures where many parameters are held in modifiable configuration files, it may well be that the scope of the changes you envision could be affected using these,

There are, of course, a few FSTD operators that still retain full engineering departments and have it in mind to be able to carry-out major updates and up-grades in the future. Full self sufficiency which needs source code to achieve.

They have given me source code so I am OK, right?

Well, maybe. Having the source code is only one step along the path to self sufficiency, there are a number of other items to put in place.

There will be a number of tools, developed by the TDM and purchased, that you will require in order to create and build a new load. Items such as the compiler (assuming your TDM uses a Commercial of the Shelf (COTS) compiler) can be purchased but some of the tools are developed by the TDM. For example, on the latest data centric aircraft the TDMs have developed tools that read in the aircraft Original Equipment Manufacturers (OEM) Interface Control Document (ICD) data to automatically populate the FSTD variable databases. To be really sure of self sufficiency you will need the source code for these tools in case of changes to the aircraft data formats, not an unheard-of event.

You will also need to be careful to ensure you receive all the TDM software and are able to change them, with the use of modern high level languages the TDMs have taken advantage and produced software reliant on precompiled libraries when compiling the full load.

More prosaically you will need to ensure you have the appropriate engineering capabilities, in-house or contracted, both personnel and facilities to use the source code and tools.

As we discussed in a previous blog, it may well be that your FSTD was originally delivered with a product load. Assuming you have obtained the source code and successfully updated the FSTD, if this is the case should you need the TDM to update the device in the future you may well be faced with the choice of the TDM using their latest load, and you losing your changes, or having them produce a bespoke load based on your as maintained load. This will come at a premium.

Escrow Considerations

Just because you have negotiated an escrow agreement that is not necessarily full protection. As we have seen the TDMs will not be able to, or be permitted to, place all the source in escrow. Particularly for LRUs that are re-targeted they are usually not permitted to distribute the code they receive from the LRU OEM. As an operator you will need to ensure you have agreements in place with the LRU OEMs in order to permit this, spoiler alert: they may not be inclined to grant this, and it certainly won’t be free.

Now assuming that all the obstacles in getting all the elements you or your selected software developer will need have been identified, including finding a reliable escrow agent, you now need to make sure there is a robust process in place. As most people in our industry will attest an FSTD is rarely perfect at Ready For Training (RFT), there are normally Discrepancies Reports (DRs) outstanding. As each of these is corrected the software changes will need to be uploaded to the escrow agent, bear in mind that some of these DRs may linger past the warranty period and escrow becomes an ongoing process.

So, is it worth the effort?

A simple requirement in a Request for Quotation (RFQ) that says give us all the source code, apart from being naïve, is unlikely to achieve the goal the writer has in mind. As we have seen, even if the TDM may be minded to supply the source code, they have problems in doing so and what you receive may be insufficient.

Even if you are only looking at long term protection from the TDM ceasing trading or declaring your FSTD obsolete, escrow is, frankly, unlikely to work. The chances of getting access to the source out of escrow fifteen years after RFT with it being complete, up-to-date and being able to use it are minimal.

Are there strategies available that will work? Well possibly: the only way to be certain is to purchase a full software development station to be delivered with your FSTD and insist that all new loads are compiled on the development station and deployed to the FSTD by your staff. You will need to retain at least two fully trained and qualified Engineers; this will cost you approximately $250,000 per year, adding over $40 per hour to the cost of running a single FSTD, so out of reach of most training centres. A cheaper alternative is to insist that the TDM retains the source code on the FSTD, perhaps in a private directory, and compiles on the device.

How can Sim Ops Help?

At Sim Ops we can help you ensure that at the point of purchase this complex issue is addressed contractually. We can also assist in the negotiations with the TDM to find an acceptable solution. Read more about how we can assist you with during the acquisition of a simulator; and contact us.

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