4.6 Position Measurement and Evidence

4.6.1 Position measurement

Flight position data requirements may be fulfilled by any of the following measuring methods:

a. By direct observation from the ground for start, turn, and finish points,

b. Satisfactory photographic evidence from a camera in the glider;

c. Satisfactory data from a flight recorder in the glider.

4.6.2 Position evidence - general

a. POINT OF RELEASE

Evidence of point of release may be provided by the pilot of the towplane or the person supervising the ground launch of the glider.

b. HEIGHT OF RELEASE

The height of release shall normally be obtained from a barogram. External measurement (see 4.7.1) may be used only when the required accuracy can be verified.

c. CROSSING A START LINE

(i) When the start line is controlled by observation from the ground, visual observation of a crossing in the direction of the first leg at an altitude of not more than 1000 metres above the line.

(ii) When using flight recorder evidence, by clear proof that the start line was crossed in the direction of the first leg.

d. CROSSING A FINISH LINE

(i) When the finish line is controlled by observation from the ground, the nose of the glider crosses the finish line unassisted from the direction of the last leg at a height of not more than 1000 metres above the line.

(ii) When using flight recorder evidence, by clear proof that the finish line was crossed from the direction of the last leg.

e. WAY POINTS

Way points should be of such a nature that they are easily recognisable from the air. Where photography is used, way points shall be point features and should be selected to make interpretation of photographs easy, even on photographs taken in
difficult light conditions such as low contrast. Where a flight recorder is being used for verification, the way point coordinates do not need to represent a point feature on the ground.

f. OBSERVATION ZONE

Evidence is required that the glider was within the observation zone (1.1.5) of a way point used during the flight. This may be collected by using one or more of the following
three methods:

(i) Direct observation, in which the glider is positively identified as being within the observation zone by an OO on the ground at the turn point. Magnification and tracking devices may be used.

(ii) Photographic, where the pilot presents a satisfactory photograph taken from within the observation zone in accordance with the rules for photographic evidence below.

(iii) Flight recorders, where (in accordance with the IGC rules for the use of this equipment (see 4.6.4), the data record shows incontrovertible proof that the glider was in the
observation zone, with one position fix recorded either exactly on the position of the waypoint or within the observation zone, or else a straight line drawn between two consecutive valid fixes crosses
the observation zone. See Annex C para 4.6 and 7.1c.

4.6.3 Photographic position evidence

Cameras can be used on badge flights to provide evidence of position and generally substantiate the soaring performance by means of a sequence of photographs on a single length of film. There shall be proof that all photographs were taken from the glider on the flight concerned and that turn point(s) were photographed between the start time and finish time.

a. PHOTOGRAPHIC CONTROL METHOD

The following method shall be used:

(i) Mounting in the cockpit

The camera must be held in fixed mountings in the cockpit so that every photograph will show the wingtip. The lens housing should be positioned inside the canopy or camera window so that the random line mentioned in (iii) below will show on the film (this does not apply to open-cockpit gliders). See Annex C para 3.4.

(ii) Sealing the camera

The camera must be sealed unless the same OO is controlling both the pre-flight photograph(s) and the processing of the film, in which case sealing is not necessary. When a time recording camera is used
to supply time evidence, it must be sealed by an OO before the flight in such a way that the film cannot be removed and the time adjusting mechanism cannot be accessed until the seal is broken by an OO after flight.

(iii) Before takeoff

Just prior to takeoff an OO shall mark the outside of the canopy or window across the front of the lens with a random line and display the flight declaration for the pilot to photograph with the camera
installed.

The random line should be dark or opaque and at least 3 mm wide if it is to show on the image.

(iv) After flight

Following landing and the completion of the photographic sequence, an OO shall take charge of the film and have it developed. Every effort is to be made to preserve the film as a continuous strip.
However, if it is cut or broken while out of control of the pilot or OO, this evidence remains valid if close examination of the pieces show that they form the original continuous length of film. An OO shall describe the circumstances under which the film was broken or cut.

b. PHOTOGRAPH SEQUENCE

The film shall contain photographs in the following sequence:

(i) the pre-flight clock synchronisation photo(s) if a time camera is used, (see 4.5.1c and 4.5.2a),

(ii) the declaration,

(iii) at least one photograph showing indisputable evidence of the presence of the glider in each of the observation zone(s) of the way point(s) used, in the correct sequence,

(iv) the glider on the landing field with surrounding features and its registration markings appearing clearly on the photo, or the above declaration with landing time added.

(v) the post flight synchronisation photo(s) if a time camera is used.

Photographs in (ii) and (iii) above must show the shape of the canopy mark (see 4.6.3a(iii)) on the film image. Additional photos which may have been taken after the declaration and before the landing must also show the canopy mark.

4.6.4 Flight recorder (GNSS) position and other evidence

All flight recorder evidence must be produced by an FAI/IGC approved system. The WGS84 Geodetic Datum shall be set for all Lat/Long data that is recorded and transferred after flight for analysis. Data
must be produced from a flight recorder that has an IGC-approval for the type of soaring performance that is claimed. Any FR used on the flight must comply with the conditions of its approval. The approval documents for each type of recorder will be posted on the FAI gliding/gnss web pages and shall specify procedures to be used, any limitations, and advice on its use. See Annex B Chapter 1.

a. FLIGHT RECORDER CONTROL METHOD

The OO shall familiarise himself with the terms of the approval for the GNSS and flight recorder equipment concerned. See Annex C, Appendix 6 para 2.3. There must be incontrovertible evidence, independent of the FR data, that the FR from which the flight data was taken was in the glider flown by the pilot during the claimed soaring performance.

(i) Before the flight

The OO shall sign the pilot's written flight declaration, except where the declaration is stored electronically in the flight recorder (1.3.2). The OO shall enter a secret code into the flight recorder if the IGC approval for the
equipment requires this. The flight recorder system shall be placed, configured or sealed in such a way that it will be physically impossible to operate any controls other than those specifically allowed for use in flight; and to connect or disconnect any device to the flight recorder system other than in accordance with the IGC approval for the equipment. The method(s) of sealing, if any, shall be specified in the IGC approval for the equipment.

(ii) Takeoff and landing

An OO shall ensure that there is evidence for the times and points of takeoff and landing, pilot(s) names, glider type and registration, and the type and serial number of the FR for flight evidence. This evidence shall be independent of the data produced by the FR. See Annex C para 11.3.

(iii) After flight

After landing, the flight data shall be transferred from the FR to a memory device acceptable to the NAC via a PC or other device in the manner specified in the IGC approval for the equipment. The OO shall check any seals which were applied before the flight. The flight data shall then be sent to a person approved by the NAC to make the analysis. This may be by physical dispatch of the memory device or by e-mail if acceptable to the NAC. For world record claims, a copy of the .igc file is to be sent to the FAI within 7 days along with the notification of a claim (see 3.2). This process must be performed for all FRs carried during the flight.

b. DATA ANALYSIS

Analysis of the flight data shall be performed by a qualified person, approved by the NAC, whose duty is to ensure that the appropriate evidence is present to verify the attainment of way points, heights, times and position. Analysis guidelines are in Annex C. Where there is more than one FR, the one holding the last declaration (the primary FR) shall normally be used for analysis. If the primary FR has a failure, a secondary FR may be used for verification provided it has the same declaration and flight data details. A difference in the declaration on a secondary FR from the primary FR could be grounds for refusal to accept any claim from that flight.

If the soaring performance qualifies for a badge or record, the following shall be forwarded to the NAC:

(i) The original data on the memory device (the first copy) storing the flight data for each FR. This must include the data file in *.igc format, and the file in its original format (if different) as transferred
from the flight recorder immediately after landing.

(ii) The appropriate claim form(s), including OO's evidence that manually recorded times and exact locations correspond to the equivalent flight recorder data.

(iii) For free record flights, the achieved way points shall be determined from the flight recorder evidence and specified in the claim for the record. The flight recorder "pilot event marker", if incorporated, may be used to indicate the desired waypoint position(s).

(iv) Any other measured data and/or auxiliary material required by a NAC to support the mandatory evidence. See examples in Annex B, Appendix 1.