AMC4 FSTD(A).300  Guidance on design and qualification of basic instrument training devices (BITDs)

(a)     Background

(1)     Traditionally, FSTDs used by the ab-initio 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 a competent authority inspector.

(2)     CS-FSTD(A) introduces two new devices, flight and navigation procedures trainer (FNPT) type I and FNPT type II, where 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.

(3)     CS-FSTD(A) sets also the requirements and guidelines for the lowest level of FSTDs by introducing BITDs. It should be clearly understood that a BITD can never replace an FNPT I. The main purpose of a BITD is to replace an old instrument training device that cannot be longer approved either due to poor fidelity or system reliability.

(b)     Design standards

(1)     Unlike FFS devices, a BITD is intended to be representative of a class of aeroplane. The configuration chosen should broadly represent the aeroplane likely to be used as part of the overall training package. It would be 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’.

(2)     The student pilot station should be broadly representative of the designated aeroplane configuration and should be sufficiently enclosed to exclude any distractions.

(3)     The main instrument panel in a BITD may be displayed on a cathode ray tube (CRT). Touch screen or mouse and keyboard operation by the student pilot would not be acceptable for any instrument or system.

(4)     The standards for BITDs were developed for low cost devices and therefore were kept as simple as possible. With advances in technology the higher standards defined for FFSs and FNPTs should be used where economically possible.

(c)      Validation Data

(1)     The data used to model the aerodynamics and engine(s) should be soundly based on the designated aeroplane configuration. It is not acceptable if the models merely represent a few key configurations.

(2)     Recognising the cost and complexity of flight simulation models, it should be possible to generate a generic class typical model. Such models should be continuous and vary sensibly throughout the required training flight envelope. A basic principal 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, including:

(i)      aeroplane design date;

(ii)     flight and maintenance manuals; and

(iii)     observations on ground and during flight.

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

(i)      video;

(ii)     pencil and paper;

(iii)     stopwatch;

(iv)     new technologies like GPS etc.

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 should be carefully documented and available for inspection by the competent authority as part of the qualification process.

(d)     Limitations

A force cueing system may be spring-loaded. But it should be remembered that it is vitally important that negative characteristics are not acceptable.

(e)     Testing and 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 higher level training devices.

The validation tests specified in AMC1 FSTD(A).300(b)(3) should be flown by a suitably skilled person and the results recorded manually. However, a print-out of the parameters of interest is highly recommended, thereby increasing the repeatability of the achieved results.

The tolerances specified are designated 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 competent authority in advance of any formal qualification process. For initial qualification, it is highly desirable that the device meets its design criteria within the listed tolerances. However the tolerances contained in this CS are specifically intended to be used to ensure repeatability during the life of the device and in particular at each recurrent competent authority evaluation.

Most of the tests within the qualification test guide (QTG) had their tolerances reduced to correct trend and magnitude (CT&M). 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 approximate and representative of the simulated class of aeroplane and should under no circumstances exhibit negative characteristics. In all these cases it is strongly recommended to print out the baseline results during initial evaluation thereby avoiding the effects of possible divergent subjective opinions during recurrent evaluations.

The subjective tests listed under AMC1 FSTD(A).300(c), functions and manoeuvres, should be flown out by a suitably qualified and experienced pilot. Subjective testing should not only review the interaction of all the applicable systems but the integration of the BITD within a training syllabus, including:

(1)     the training environment;

(2)     freezes and repositions; and

(3)     the navaid environment.

In parallel with this objective and subjective testing process, it is envisaged that suitable maintenance arrangements as part of a compliance monitoring programme are in place. Such arrangements should cover routine maintenance, the provision of satisfactory spares supply and personnel.

(f)      Guidelines for an instrument panel displayed on a screen

(g)     Additional Information

Unlike with other FSTDs the manufacturer of a BITD has the responsibility for the initial evaluation of a new BITD model. Because all serial numbers of such a model are automatically qualified, the ATO certificate containing the specification of the device and the extent to which it may be used at the operator’s site becomes more important before the course approval is granted.