SkyDemon Mobile Documentation: Instruments
Instruments are displayed around the edges of the main map and show you current GPS and navigational information. Some instruments have settings that can be adjusted. The Instrument Options screen can be found under the Settings menu, or you can slide your finger over any instrument, towards the main map, to bring it up.
Direction Indicator
The direction indicator is a compass rose that always rotates such that your current track over the ground is displayed at the top, with the exact value shown in a box in the middle. When flying a course, a bug appears on the outside of the dial representing the track you should be flying to get to your next waypoint.
The values shown in the direction indicator are in degrees true by default but can be switched to degrees magnetic from the Instrument Options screen. The direction indicator can also be hidden from this screen, to reveal more of the main map.
When hidden, the direction indicator is replaced by a small instrument called the course correction indicator. When you are navigating towards a waypoint, this simply appears when you need to make a course adjustment such as to turn left by 10 degrees.
You can see both instruments in the figure on the right. Both are showing the same status (you need to turn left by 10 degrees) but the DI shows more information and occupies a lot more screen space.
Groundspeed
The exact speed of the aircraft over the ground is displayed in this instrument. By default the units used are knots. To change units, open the Settings menu and select Change Units. There are three possible units of measurement for distances and speeds, which are tied together. They are:
| Distance Unit | Speed Unit | |
|---|---|---|
| Option 1 | Nautical Miles | Knots |
| Option 2 | Statute Miles | Miles per Hour |
| Option 3 | Kilometres | Kilometres per Hour |
Altimeter
The exact altitude of the aircraft above local mean sea level is displayed in this instrument. Units are always feet. A small coloured flag in the top left corner of the instrument indicates the accuracy of the altitude readout:
 | Green Plus or minus 50 feet |
 | Orange Plus or minus 200 feet |
|
 | Yellow Plus or minus 100 feet |
 | Red More than 200 feet of inaccuracy |
Calibration
Some devices were not meant to be used aloft and consequently their GPS chipsets do not perform necessary corrections to altitude to make it usable by pilots. If the background of the altimeter is red, this is the case. Press the instrument to calibrate it manually by entering your current altitude.
TIP: Click the altimeter when you are standing on an airfield and SkyDemon will automatically calibrate the altimeter based on the elevation of the field.
Virtual Radar
This powerful instrument shows a projection of your current course and all the objects of relevance in your path. This data is a snapshot taken every five to ten seconds, laid out with your current position on the left and the extremity of the data on the right.
An aeroplane symbol represents your current position. A line denoting vertical trajectory projects from the aeroplane, with the same dots representing 2, 5 and 10 minutes ahead (or miles, if you have specified this in Preferences). This gives an idea of current vertical speed and where your ascent or descent will leave you after a period of time.
Terrain is laid out in front of you, making it very easy to detect any unintended proximity to it. Airfields, towns, reporting points and obstructions that you will pass close to are displayed as well.
This instrument has a context menu that can be used to inspect certain features on it, just like the main map. Hold your finger on any part of it to see the list of objects at that point which you can inspect. Another feature of the context menu is that it will tell you the distance and time to reach the point at your fingertip. So, if ATC ask you for your estimated time to a reporting point, you have only to tap your finger on the reporting point and hold it there and you'll be able to give an exact answer.
