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General: FAQ Frequently Asked Questions about the CIMA standard for flight recorders
What is the standard all about? This is quite complex technology, to avoid a myriad of different and incompatible data formats, units, map datums, time-bases etc. which would make their use, especially in championships, a difficult and unreliable business we had to come to an agreement about some sort of specification or standard. As it happens, the International Gliding Commission (IGC) has a well developed and extremely detailed standard which has been extensively proven in gliding championships and records since it was created in 1995 so it was not necessary to invent something completely new. A document based on the IGC standard but adapted to our unique demands was presented to the November 2002 CIMA meeting with the view to it being incorporated into Section 10 as a new Annex 6. The meeting accepted the document and it is now incorporated in the FAI Sporting code for microlights and paramotors as Annex 6 "GNSS Flight recorders".
Why do we need a standard at all? The primary need for this standard however is in championships where flight recorders help solve the perennial and expensive problems associated with marshalling and scoring big microlight championships. Benefits include:
Why can't I use the recording facility of the GPS I already own? In championships, approved flight recorders must be used because the crew must not have access to any GPS flight information. If they did, then the whole thing would very soon become so easy that we may as well abandon traditional championships altogether and stay at home and do them on flight simulators connected to the Internet. Sometimes when there are not enough approved FR's to go round, other types can be 'sealed' into a bag but this is a very unsatisfactory solution as the pilot has no idea it is even switched on and without the specialist software of approved FR's which streamlines the data transfer, getting the information out of them is time-consuming and error-prone. There are other good reasons too:
There is no reason why CIMA can't approve an "off the shelf" GPS which satisfied the standard and had some sort of 'lock-out' feature which could be set by the organization to prevent the pilot from getting any flight information during a championships but which otherwise could be used as a normal receiver. Detailed conditions of use would simply be included in the approval document.
Why do we need such detail in the specification?
What does the specification mean?
Second, it defines the exact format the data must be in when it is transferred from FR to PC. The primary objective here is to get the data out of the FR and into a PC as quickly and reliably as possible in a common data-format using common units of measure, map datum, time-base Etc. The IGC format for FR data is readable by many different flight analysis programs. To ensure consistent auditable data the standard defines exactly the "mandatory data sub-set" required for Type 1 approval within the IGC format. Third, it describes the system and method of approval of FR's to CIMA Type 1 standard and the sort of testing which should be done.
How reliable are they - really? The first time FR's were used as the 'primary' source of pilot performance in a World championships was at WMC 2003 in UK. An analysis after the event suggested the FR's used were better than 95% reliable and nearly all errors were 'pilot induced'; either the FR was incorrect positioned in the aircraft so the antenna was getting a restricted view of the sky, or pilots were forgetting to switch them on. Flight recorders have been used as 'primary' in every major microlight and paramotor championships since then. Most errors since then have been caused by the organizer not getting correct physical fixes of the points used in scoring. These are usually fixable during the event, though it usually causes considerable delays to the final scoring.
Who will buy these flight recorders? More importantly, pilots need to practice with them so they are confident of their own FR's capabilities and limitations in their own aircraft, for example, it is quite easy to obscure the antenna, especially in a paramotor. The style in which tasks are flown will also be slightly different which will also need practice (eg reliably being able to hit a 200m radius cylindrical scoring zone). Ultimately they are very much for each pilot's benefit, they are not an unnecessary 'imposition' and they need not be expensive.
How are pilots scored in championships? A Start line, IP or gate time is taken from the fix immediately before the line is crossed. A Finish line or FP time is taken from the fix immediately after the line is crossed. For many reasons it is impractical to deduce the exact time a FR crosses a timing gate from the two adjacent fixes, it is therefore to the pilot's advantage to have a FR which records frequent fixes; ideally 1 each second.
What problems can arise in championships? One map is the printed map the pilot uses. The other is the "GPS map" which is projected onto the surface of the earth by some satellites which the scoring system uses. The important thing is to reconcile the two in all cases where scoring is involved, it is not good enough to have a "calibrated" map like you can do quite accurately with Oziexplorer because it still does not account for the unknown number of "artistic" differences between the printed map and the GPS map, and ALL maps have artistic differences. It is not so difficult to do however - the Director can plan the task on the printed map but the key is that he MUST visit every point which involves scoring by land or air and get the true GPS coordinate fix. It does not matter whether it is a turnpoint, a hidden gate, a marker or a secret photo, he must have a true fix. Getting coordinates off the printed map and putting them in the GPS mapping system does NOT reconcile the two maps; this has been demonstrated a number of times by lazy organizers. The pilot flies with the printed map but the FR is recording off the GPS map. If the pilot passes the turnpoint correctly on the printed map, then, because the director has been there and got the GPS fix, he knows the pilot has been there on the GPS map even if there is an "artistic" displacement between the two when the two maps are overlayed. (This is very easy to demonstrate in Oziexplorer). A good example: Draw a straight line on the printed map which goes from a known point, through a known point, to a third known point, eg road junctions all maybe 20 Km apart. Go to those points, get the GPS coordinates and plot them mathematically into Oziexplorer or something like it. It is almost guaranteed that the mathematically plotted line through the three points using the GPS coordinates will not be exactly a straight line - but if you think about it, it doesn't matter, because all you are interested in is the points and all the pilot is interested in is flying the straight line on the map. The problem becomes more complex when you start scoring declared average speeds Etc. but if you always think through the problem on the basis that the "two maps" must always be reconciled, then there is always a solution. There are various other problems specific to FR's:
What analysis software is available?
The future...
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