Aircraft rating system

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With hundreds of aircraft available for FlightGear, it is very difficult to find the true gems. The rating system below attempts to solve this by providing a quick objective way to rate aircraft. This was discussed in some detail on the -dev mailing list in December 2010.

The rating system scores an aircraft (0-5) in 4 individual criteria - FDM, Systems, Cockpit and External Model.

These ratings can then be encoded in the aircraft -set.xml file from where they can be picked up by launchers, web pages etc.

The sum of the scores in the 4 criteria provides an overall score from 0 to 20, which can be mapped to a textual overall aircraft status.

Flight Dynamics Model

  • 0: None, or using FDM from other aircraft
  • 1: JSBSim Aeromatic or YASim geometric model used without tuning. Flaps modeled.
  • 2: FDM tuned for cruise configuration.
  • 3: FDM tuned for rate of climb and cruise PoH performance numbers
  • 4: FDM matches PoH in 90% of configurations
  • 5: FDM matches PoH and most known test data.


  • 0: No controllable systems: engine is always on, generic radio,
  • 1: Generic engine start/stop (}}s), correct size/number of fuel tanks, generic (untuned) autopilot, working flaps/gear
  • 2: Working electrical system, fuel feed cockpit controls, stable autopilot
  • 3: Accurate startup procedure, tuned autopilot with cockpit controls matching real aircraft systems, generic failure modelling (Vne, +ve/-ve G, gear limits)
  • 4: Primary aircraft-specific systems modelled (aero-tow, radar, GPWS, weapons). User able to follow normal PoH checklists (e.g. startup, shutdown) in entirety
  • 5: Some aircraft-specific failure modes implemented (e.g. flame-out, inverted engine limitations). Some emergency procedures implemented (RAT, emergency gear release), able to follow some emergency PoH checklists in entirety.

Ignore systems not present on the aircraft IRL. If the real aircraft doesn't have a system (e.g. autopilot), the FG model shouldn't have either and if all systems in the real aircraft are modeled then it scores a 5 even if it is a very simple aircraft.


  • 0: No cockpit
  • 1: 2D panel, no cockpit.
  • 2: 2D panel in 3D cockpit, or incomplete 3D panel
  • 3: 3D panel and cockpit
  • 4: 3D panel and accurately modelled 3D cockpit, plain texturing. Hotspots for majority of controls.
  • 5: 3D panel and accurately modelled 3D cockpit with photo-realistic texturing.

External Model

  • 0: None
  • 1: Simple 3D model, no animations
  • 2: Accurate 3D model with animated control surfaces (elevator, aileron, rudder, flaps)
  • 3: Accurate 3D model with animated control surfaces, gear detailing (retraction, rotation), prop
  • 4: Accurate 3D model with animated control surfaces, gear, prop, livery support (if applicable).
  • 5: Highly accurate 3D model (down to minor components such as control rods), with animated control surfaces, gear, prop, livery support, tyre smoke, shader effects.

Objectively differentiating between a 4 and a 5 is very difficult. As a guideline, a "5" model is as realistic as possible given the available rendering technology.

Overall Status

Sum the ratings of the 4 criteria, to produce an overall score from 0 to 20.

This maps to overall status as follows:

  • 18 or higher : advanced production (minimum 4 in each rating)
  • 16 to 17 : production (minimum 4 in each rating)
  • 12 to 15 : early production (minimum 3 in each rating)
  • 9 to 11 : beta
  • 8 or lower : alpha

Encoding the rating

The ratings should be encoded in the -set.xml file for the aircraft, under <sim> as follows.

<status>early production</status>
 <FDM type="int">5</FDM>
 <systems type="int">4</systems>
 <cockpit type="int">3</cockpit>
 <model type="int">3</model>