AMC3 FSTD(A).300  Guidance on design and qualification of flight and navigation procedures trainers (FNPTs)

(a)     Background

(1)     Traditionally training devices used by the ab-initio professional pilot schools have been relatively simple instrument flight-only aids. These devices were loosely based on the particular school's aeroplane. The performance would be approximately correct in a small number of standard configurations, however the handling characteristics could range from rudimentary to loosely representative. The instrumentation and avionics fit varied between basic and very close to the target aeroplane. The approval to use such devices as part of a training course was based on a regular subjective evaluation of the equipment and its operator by an inspector of the competent authority.

(2)     CS-FSTD(A) introduces two new devices: FNPT I & FNPT II. The FNPT I device is essentially a replacement for the traditional instrument flight ground training device taking advantage of recent technologies and having a more objective design basis. The FNPT II device is the more advanced of the two defined standards and fulfils the wider requirements of the various Part-FCL professional pilot training modules up to and including (optionally with additional features) multi-crew cooperation (MCC) training.

(3)     The currently available technologies enable such new devices to have much greater fidelity and lower life-cycle costs than was previously possible. A more objective design basis encourages better understanding and therefore modelling of the aeroplane systems, handling and performance. These advances combined with the ever upwardly spiralling costs of flying and with the environmental pressures all point towards the need for revised standards.

(4)     The FNPT II device essentially bridges the gap in design complexity between the traditional subjectively created device and the objectively based level A full flight simulator (FFS).

(5)     These new standards are designed to replace the highly subjective design standards and qualification methods with new objective and subjective methods, which ensure that the devices fulfil their intended goals throughout their service lives.

(b)     Design standards

Two sets of design standards are specified within CS-FSTD(A): FNPT I and FNPT II, the more demanding of which is FNPT II.

(1)     Simulated aeroplane configuration

Unlike FFS devices, FNPT I and FNPT II devices are intended to be representative of a class of aeroplane (although they may in fact be type specific).

The configuration chosen should sensibly represent the aeroplane or aeroplanes likely to be used as part of the overall training package. Areas such as general layout, seating, instruments and avionics, control type, control force and position, performance and handling and powerplant configuration should be representative of the class of aeroplane or the aeroplane itself.

It is in the interest of all parties to engage in early discussions with the competent authority to broadly agree a suitable configuration (known as the designated aeroplane configuration). Ideally any such discussion should take place in time to avoid any hold-ups in the design/build/acceptance process thereby ensuring a smooth entry into service.

(2)     The cockpit/flight deck

The cockpit/flight deck should be representative of the designated aeroplane configuration. For good training ambiance the cockpit/flight deck should be sufficiently enclosed for FNPT I to exclude any distractions. For an FNPT II the cockpit/flight deck should be fully enclosed. The controls, instruments and avionics controllers should be representative: touch, feel, layout, colour and lighting to create a positive learning environment and good transfer of training to the aeroplane.

(3)     Cockpit/flight deck components

As with any training device, the components used within the cockpit/flight deck area do not need to be aircraft parts: however, any parts used should be representative of typical training aeroplanes and should be robust enough to endure the training tasks. With the current state of technology the use of simple cathode ray tube (CRT) monitor-based representations and touch screen controls would not be acceptable. The training tasks envisaged for these devices are such that appropriate layout and feel is very important: i.e. the altimeter sub-scale knob needs to be physically located where it is in the represented class of aeroplane either equipped with glass cockpit avionics or classic instruments. The use of CRTs with physical overlays incorporating operational switches/knobs/buttons replicating an aeroplane instrument panel may be acceptable to the competent authority.

(4)     Data

The data used to model the aerodynamics flight controls and engines should be soundly based on the “designated aeroplane configuration”. It is not acceptable and would not give good training if the models merely represented a few key configurations bearing in mind the extent of the credits available.

Validation data may be derived from a specific aeroplane within a set of aeroplanes that the FNPT is intended to represent, or it may be based on information from several aeroplanes within a set/group/range (the designated aeroplane configuration). It is recommended that the intended validation data together with a substantiation report be submitted to the competent authority for evaluation and approval prior to the commencement of the manufacturing process.

(i)      Data collection and model development

         Recognising the cost of and complexity of flight simulation models, it should be possible to generate generic class typical models. Such models should be continuous and vary sensibly throughout the required training flight envelope. A basic requirement for any modelling is the integrity of the mathematical equations and models used to represent the flying qualities and performance of the class of aeroplane simulated. Data to tune the generic model to represent a more specific aeroplane can be obtained from many sources without recourse to expensive flight test:

(A)     aeroplane design data;

(B)     flight and maintenance manuals; or

(C)     observations on ground and in the air.

Data obtained on the ground and in flight can be measured and recorded using a range of simple means such as:

(A)     video

(B)     pencil and paper

(C)     stopwatch

(D)     new technologies (i.e. GPS).

Any such data gathering should take place at representative masses and centres of gravity. Development of such a data package including justification and the rationale for the design and intended performance, the measurement methods and recorded parameters (e.g. mass, c of g, atmospheric conditions) should be carefully documented and available for inspection by the competent authority as part of the qualification process.

(5)     Limitations

         A further possible complication is the strong interaction between the flight control forces and the effects of both the engines and the aerodynamic configuration. For this reason a simple force cueing system in which forces vary not only with position but with configuration (speed, flaps, trim) will be necessary for the FNPT II device. For an FNPT I device a force cueing system may be spring-loaded, but it should be remembered that it is vitally important that negative characteristics would not be acceptable.

         It should be remembered however that whilst a simple model may be sufficient for the task, it is vitally important that negative characteristics are not present.

(c)      Visual

Unless otherwise stated below, the visual requirements are as specified for a level A FFS.

(1)     Other than field-of-view (FoV) specific technical criteria for the visual systems are not specified. The emergence of lower cost raster-only daylight systems is recognised. The adequacy of the performance of the visual system will be determined by its ability to support the flying tasks, e.g. “visual cueing sufficient to support changes in approach path by using runway perspective”.

(2)     The need for collimated visual optics is probably not necessary. A single channel direct viewing system (single projector or a monitor for each pilot) would probably be acceptable as no training credits for landing are available. Distortions due to non-collimation would only become significant during on ground or near to the ground operations.

(3)     The minimum specified vertical FoV of 30 degrees may not be sufficient for certain tasks.

         Where the FNPT does not simulate a particular aeroplane type, then the design of the out-of-cockpit/flight deck view should be matched to the visual system such that the pilot has a FoV sufficient for the training tasks.

         For example during an instrument approach the pilot should be able to see the appropriate visual segment at decision height. Additionally, where the aeroplane deviates from the permitted approach path, undue loss of visual reference should not occur during the subsequent correction in pitch.

(4)     There are two methods of establishing latency, which is the relative response of the visual system, cockpit/flight deck instruments and initial motion system response. These should be coupled closely to provide integrated sensory cues.

         For a generic FNPT, a transport delay test is the only suitable test that demonstrates that the FNPT system does not exceed the permissible delay. If the FNPT is based upon a particular aeroplane type, either Transport Delay or Latency tests are acceptable. Response time tests check response to abrupt pitch, roll, and yaw inputs at the pilot's position is within the permissible delay, but not before the time when the aeroplane would respond under the same conditions. Visual scene changes from steady state disturbance should occur within the system dynamic response limit but not before the resultant motion onset.

         The test to determine compliance with these requirements should include simultaneously recording the analogue output from the pilot's control column, wheel, pedals, the output from the accelerometer attached to the motion system platform located at an acceptable location near the pilots’ seats, the output signal to the visual system display (including visual system analogue delays), and the output signal to the pilot's attitude indicator or an equivalent test approved by the competent authority. The test results in a comparison of a recording of the simulator’s response with actual aeroplane response data in the take-off, cruise, and landing configuration.

         The intent is to verify that the FNPT system transport delays or time lags are less than the permissible delay and that the motion and visual cues relate to actual aeroplane responses. For the aeroplane response, acceleration in the appropriate rotational axis is preferred.

         The transport delay test should measure all the delay encountered by a step signal migrating from the pilot's control through the control loading electronics and interfacing through all the simulation software modules in the correct order, using a handshaking protocol, finally through the normal output interfaces to the motion system, to the visual system and instrument displays. A recordable start time for the test should be provided by a pilot flight control input. The test mode should permit normal computation time to be consumed and should not alter the flow of information through the hardware/software system.

         The transport delay of the system is therefore the time between control input and the individual hardware responses. It need only be measured once in each axis.

(5)     Care should be taken when using the limited processing power of the lower cost visual systems to concentrate on the key areas which support the intended uses, thereby avoiding compromising the visual model by including unnecessary features e.g. moving ground traffic, marshallers. The capacity of the visual model should be directed towards:

(i)      runway surface,

(ii)     runway lighting systems,

(iii)     PAPI/ VASI approach guidance aids,

(iv)     approach lighting systems,

(v)      simple taxiway,

(vi)     simple large-scale ground features e.g. large bodies of water, big hills; and,

(vii)    basic environmental lighting (night/dusk).

(d)     Motion

Although motion is not a requirement for either an FNPT I or II, should the operator choose to have one fitted, it will be evaluated to ensure that its contribution to the overall fidelity of the device is positive. Unless otherwise stated in these certification specifications, the motion requirements are as specified for a level A FFS, see AMC2 FSTD(A).300.

(e)     Testing/evaluation

To ensure that any device meets its design criteria initially and periodically throughout its life a system of objective and subjective testing will be used. The subjective testing may be similar to that in use in the recent past. The objective testing methodology is drawn from that used currently on FSTD.

The validation tests specified in AMC1 FSTD(A).300(b)(3) should be “flown” by a suitably skilled person and the results recorded manually. Bearing in mind the cost implications, the use of automatic recording (and testing) is encouraged thereby increasing the repeatability of the achieved results.

The tolerances specified are designed to ensure that the device meets its original target criteria year after year. It is therefore important that such target data are carefully derived and values are agreed with the appropriate inspecting authority in advance of any formal qualification process. For initial qualification, it is highly desirable that the device should meet its design criteria within the listed tolerances. However, unlike the tolerances specified for FSTDs, the tolerances contained within these certification specifications are specifically intended to be used to ensure repeatability during the life of the device and in particular at each recurrent regulatory inspection.

A number of tests within the QTG have had their tolerances reduced to correct trend and magnitude (CT&M) thereby avoiding the need for specific validation data. The use of CT&M is not to be taken as an indication that certain areas of simulation can be ignored. For such tests, the performance of the device should be appropriate and representative of the simulated designated aeroplane and should never exhibit negative characteristics. Where CT&M is used, it is strongly recommended that an automatic recording system be used to footprint the baseline results, thereby avoiding the effects of possible divergent subjective opinions during recurrent evaluations.

The subjective tests listed under “Functions and Manoeuvres” (AMC1 FSTD(A).300(c) should be flown out by a suitably qualified and experienced pilot.

Subjective testing will review not only the interaction of all of the systems but the integration of the FNPT with the following:

(a)      training environment

(b)     freezes and repositions

(c)      navaid environment

(d)     communications

(e)     weather and visual scene contents.

In parallel with this objective/subjective testing process, suitable maintenance arrangements as part of a compliance monitoring programme should be in place. Such arrangements should cover routine maintenance, the provision of satisfactory spares holdings and personnel.

(f)      FNPT type I

         The design standards, testing and evaluation requirements for the FNPT Type I device are less demanding than those required for a FNPT Type II device. This difference in standard is in line with the reduced Part-FCL credits available for this type of device.

(g)      Additional features

         Any additional features in excess of the minimum design requirements added to an FNPT type I & II should be subject to evaluation and should meet the appropriate standards in CS-FSTD(A).