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RULE MAKING
GPS Starts and Finishes
Updated April 23, 1999
For 1999, GPS-controlled starts will be used only at the Open and 18-Meter National contest (at Mifflin County, PA in May). This document discusses the new rules that apply when starts and finishes are controlled by Flight Recorder.
THE GPS-CONTROLLED START
A rule such as this must be precise and cover all circumstances, which can result in wording that seems complicated. Here's an explanation of the "GPS start" (the text of the rule appears below).
As part of a task, the CD sets a start cylinder. It has a center point, a radius (up to 20 miles) and a maximum height (above the home field). The idea is to get inside the start cylinder, then head for the first turnpoint. Your start comes as you exit the cylinder, either through the side or the top.
The maximum start height (MSH) will typically be set somewhat above the altitude it's easy to reach prior to the start. If you never climb above the MSH you need never worry about height.
If you do climb above the MSH you should descend and spend at least 5 minutes below the MSH before starting, or a penalty will apply. The size of the penalty will depend on how long you spent below the MSH (longer means a smaller penalty) and your largest altitude during the 5 minutes prior to your start (higher means a larger penalty).
Note that the only time that matters is the 5 minutes prior to a start, and that only your height is checked. During this time, position doesn't matter - you may be inside or outside the start radius.
Also note that no Start Time Interval applies. You are free to fly anywhere you wish prior to starting. You can make a start every 5 minutes, or wait hours between starts - so long as you have at least one start after the task opens.
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Rule 10.8.4 Flight-recorder-controlled start procedure
- Each task shall include a Start Point and a Start Radius which shall be an integral number of miles not less than 5 nor more than 20. The Start Point and Start Radius should be chosen so that pilots are likely to be able to find lift prior to starting and to return to the home field if they fail to do so. Each task shall include a Maximum Start Height (MSH) above the home field. This height shall not be less than 5000' AGL nor more than 10000' AGL. The Start Point, Start Radius, and MSH define a three-dimensional Start Cylinder. A start occurs each time a sailplane exits the Start Cylinder (either through the side or the top); at least one fix must lie within the cylinder. The following shall be determined:
- Start Fix - the latest fix within the Start Cylinder.
- Start Time - the interpolated time the sailplane exited the Start Cylinder.
- A pilot may claim a start when no fix is within the Start Cylinder; such a start incurs a penalty. The following shall be determined:
- Start Fix - the fix closest to the Start Cylinder.
- Start Time - the time of the Start Fix.
- For each start, the following shall be determined:
- Control Fix - the fix with the greatest altitude during the 5 minutes preceding the Start Fix. Control Height - the difference (in feet) between the altitude of the Control Fix and the elevation of the home field. Control Interval - the time difference (in minutes) between the Control Fix and the Start Fix.
- Start Distance - the distance (in miles) from the Start Fix to the Start Point.
- If the Control Height exceeds MSH or the Start Distance exceeds the Start Radius, a penalty will apply. The penalty will be a fixed minimum plus the sum of the following:
(Start Distance - Start Radius) * 400 (but not less than zero)
(Control Height - MSH) * (6.0 - Control Interval) / 10 (but not less than zero) The distance of the first task leg shall be taken as the distance from the Start Point to the first turnpoint, minus the Start Radius. The distance of the first task leg shall not be less than 5 miles. A pilot who suffers a flight recorder failure prior to starting should land, correct the problem, and relaunch. If the problem cannot be fixed and no suitable backup is available, the pilot may use a flight documentation method that does not control altitude (either camera or flight recorder). Documentation must show (by photo or fix) that the sailplane was within the Start Cylinder after tow release. The launch time is used as the pilot's scored start time provided it is later than the time of task opening.- Prior to a start, pilots are expected to avoid flight at indicated airspeeds greater than 115 mph while inside or within 5 miles of the Start Cylinder.
---------------------------------------------------------------------------------------THE GPS-CONTROLLED FINISHAs part of a task, the CD sets a finish cylinder. It has a center point (near the home field), a radius (up to 4 miles), and a minimum height (above the home field). Your finish comes as you enter the cylinder, either through the side or the bottom.The minimum height will be set high enough that a glider crossing the cylinder at this height should have no difficulty returning to the home field for a safe landing. If you are unable to reach the minimum height, you can still get a "rolling" finish by making a safe landing at the home field; your finish comes as your wheel stops. As with any rolling finish, a time adjustment could be applied to your finish time, if announced by the CD as part of the task.Note that you are still expected to make a radio call when four miles out, and to be alert for other traffic. Note also that GPS-controlled finishes are optional, at the discretion of the contest organizers - the ground-controlled finish through a gate remains an option.
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Rule 10.9.3 Flight-recorder-controlled finish procedure
- Each task shall include a Finish Point not more than 2 miles from the home field and a Finish Radius not greater than 4 miles. Each task shall include a Maximum and a Minimum Finish Height above the home field. The Maximum Finish Height is 5000' AGL. The Minimum Finish Height is set by the CD so that pilots who finish at or above that height can return to the home field for a normal landing. The Finish Point, radius, and maximum and minimum heights define a three-dimensional Finish Cylinder. A finish occurs when a sailplane enters the Finish Cylinder; at least one fix must lie within the cylinder. The finish time shall be taken as the interpolated time the sailplane first enters the Finish Cylinder. The distance of the final task leg shall be taken as the distance from the Finish Point to the final turnpoint, minus the Finish Radius. The distance of the final task leg shall not be less than 5 miles.
- A pilot who has suffered a flight recorder failure can request a manually-recorded finish time by radio. Such a competitor shall execute a normal rolling finish and is timed as the sailplane comes to a full stop.
---------------------------------------------------------------------------------------CONSTRUCTIVE LANDOUT / POINT OF FURTHEST PROGRESSUnder certain circumstances, the rules allow a pilot with an incomplete task to be scored to a "landing" point different from where the wheel actually touched the ground. This is known as a "constructive" landout. The situation can arise when a pilot feels that weather makes it prudent to return home without attempting all assigned turnpoints.When GPS-controlled starts are not in effect, a constructive landout can be claimed at any turnpoint - whether or not it is part of the day's task (see Rule 10.10.4i). Normal turnpoint control applies - the pilot must have a valid photo or a flight log that shows the glider was within 1/4 mile of the turnpoint. The pilot is then free to fly home; scored distance will be calculated as if he had landed at the turnpoint.When GPS-controlled starts are in effect, a pilot can claim a landout at any point, not just at a turnpoint. This called a Point of Furthest Progress (see Rule 10.10.4j). The pilot must supply the lat/lon coordinates of the chosen point, and is then scored as if the landing has been at that point.
Note that the Landing Card must show that the pilot is claiming a Constructive Landout (at a claimed turnpoint) or a Point of Furthest Progress (at a claimed lat/lon). And in each such case, the resulting scored distance must be at least half the Standard Minimum Task distance (e.g. at least 25 miles in the case of a Regional FAI-class competition).