What is it about?
One of the defining characteristics of the FLARM ecosystem from the beginning has been the obligation for regular software updates: the devices receive an “expiry date”, before which an update must be performed. If the date is exceeded without an update, an error message is displayed and the device stops working.
The original model with update cycles of 3-4 years was replaced around 2015 by a rolling scheme, where the current software always had a validity of at least 15 months: This ensures users that their devices will always function if an update is done at least once a year, e.g., in spring. This update can be easily integrated into the annual maintenance cycle, as is commonly practiced in general aviation.
Updates have been (and are) provided by us in a timely and free manner on the website, for all generations of devices. Nevertheless, there are groups of users for whom an annual update is difficult to implement:
- In certified avionics, as used in rescue helicopters, for example, a software change usually means an expensive and elaborate project for recertification.
- For infrastructure devices, such as FLARM receivers in wind turbines, access is sometimes limited and difficult.
- For paragliders or drones, there is usually no natural annual maintenance cycle. For these users, the update obligation represents an additional complexity.
The world is changing rapidly: The above use cases are becoming increasingly important for the FLARM universe. For these reasons, we have decided to replace the update obligation with an alternative system.
Why are updates important?
The crux of the matter is the radio protocol with which FLARM devices communicate: FLARM devices can only fulfill their safety function if all devices speak the same “language”.
It’s about more than just sorting bits and bytes correctly: The entire process chain from sensor to radio packet to display must be consistent to produce a reliable display in the cockpit. Aspects such as filtering of sensor data, protection of privacy, compliance with international standards, etc., need to be considered. We have extensively described our position on these topics over the years (2008, 2015, 2019).
Mandatory updates are an effective method to improve and adapt the radio protocol: At each expiry date, there is the possibility to change the protocol. We have used this opportunity repeatedly since the inception of FLARM.
In internet communication protocols, it is standard practice to agree on a common version of the protocol when establishing a connection: Usually, the highest possible version is used. For compelling reasons (such as a security issue), affected versions can be specifically deactivated.
Unfortunately, this procedure is not directly applicable to FLARM, as it does not involve a point-to-point connection: Each transmitted radio packet can, in principle, be received by dozens of devices simultaneously, all with different software versions. A connection establishment never takes place.
Therefore, we are implementing dynamic versioning: Devices choose the version of the transmitted protocol based on knowledge of other devices nearby. For example, if a current device encounters an outdated one, it situatively switches to an older protocol, depending on factors like distance or the danger of the other aircraft.
The transition to dynamic versioning is complex and requires meticulous planning: Dozens of device types from three generations with sometimes very limited resources must be considered. To manage this without interruptions, we had to take our time: We have been working on the conversion for more than three years already.
Hopefully, by mid-2024, the first software updates without an expiry date will be available for download for most devices!
Do I still need to update my device?
We still recommend updating FLARM devices once a year. On the one hand, this corrects any errors in the software and adds new features; on the other hand, older versions will be less prioritized by the network over time.