Flarm basics
Terms
A "Flarm event" is a departure, a landing or a touch-and-go that has been detected by analyzing the data from the Flarm.
The state of a plane, with regard to Flarm, is one of:
- unknown - a plane which is not in the database (typically a plane that has never been seen before)
- incomplete - a plane which is in the database, but without a Flarm ID (typically a local plane where the Flarm ID has not yet been entered in the database)
- known - a plane which is in the database with the correct Flarm ID (typically a local plane)
- incorrect - a plane which is in the database, but with an incorrect Flarm ID (typically a plane that has had a new Flarm unit installed)
Additionally, a plane may or may not have a FlarmNet entry which links the Flarm ID to the registration and contains supplementary information about the plane (e. g. type, owner...).
Note that for an unknown, incomplete or incorrect plane, there may be a plane entry in the database that has this plane's Flarm ID.
A "current" flight is one which happened today. An "old" flight is one which happened on a previous date.
In text, "Flarm" is always spelt with a capital F as a proper name, not "flarm" as a noun or "FLARM" as an acronym.
Overview
A plane with a Flarm stores a Flarm ID. The Flarm ID is typically not known initially because most people don't know or don't bother to enter the ID of their Flarm. It will therefore have to be identified during regular operation. Flarm units may be replaced or moved from one plane to another, therefore the Flarm ID of a plane may change.
A flight can also store a Flarm ID. The Flarm ID is set if and only if the flight has been created automatically. This is useful when we can't identify the plane (yet), so we can auto-land the flight later and so we can set or update the plane's Flarm ID. For more details, see Flarm handling.
General guidelines
Changes should only be made automatically if they are "fairly certain" to be correct. When in doubt, it is better to ask the user or not to perform an action than to do it wrong.
The user should never be queried except in response to an interaction; no dialogs should open spontaneously in order to avoid interfering with user operations. Information that has to be shown in response to a Flarm event must be shown unobstrusively.
We never silently create a plane. Usually, we don't silently update a plane.
The FlarmNet database is considered unreliable because the database itself may be inaccurate, or our copy of the database may be outdated. We do, however, use FlarmNet data for identifying planes and we may preset the plane editor fields with FlarmNet data when creating a plane.