Personal Black Box
Have you ever looked out the window of airplane and wondered, "What city is under the wing?", "What's that airport over there?", or "What river are we passing?"
Or have you simply wondered, "How close are is our destination?"
If so, Personal Black Box is the app for you!
Personal Black Box is a simple navigation tool designed for aircraft passengers. Personal Black Box displays a mosaic of aviation charts that you can view on your mobile device. If location information is available, Personal Black Box shows your current location, altitude, course, and speed.
Even if you cannot get a GPS signal, you can use the charts to determine your location. With a little practice, you can learn to identify where you are simply from what you see out the window and comparing that to the charts.
WARNING: Personal Black Box cannot be used to operate an aircraft or other vehicle safely. It is not designed for this purpose. Personal Black Box conserves power by limiting position updates. It does not update frequently enough to provide navigation directions. Personal Black Box does not update charts. The charts are likely to be out-of-date for navigation purpose. The included charts are modified for entertainment value and may not be safe for navigation.
Download the manual here.
Personal Black Box is here on the Itunes Store.
Personal Black Box is designed to run on a GPS-equipped iPad. Personal Black Box is a universal application that runs on either an iPhone or iPad. If the iPad has a cellular plan, that should be disabled if run while in an aircraft. Location services may require Wi-Fi to be enabled. Many airlines permit this.
Personal Black Box is a universal application that will run on iPhones as well.
Personal Black Box can be used for reference purposes without location services.
Personal Black Box DOES NOT require a subscription.
Charts may be downloaded as in app purchaces from the Itunes store. Current coverage is:
- Continental U.S. (Visual and Instrument)
- Carribean (Visual)
- Alaska (Visual and Instrument)
- Hawaii (Visual and Instrument)
- Pacific (Instrument)
- Atlantic (Instrument)
You can download charts for free and are limited only by download time and storage.
How to Use Personal Black Box
Personal Black Box has an easy-to-use interface. You can
- Drag to scroll the contents.
- Pinch to zoom the contents
- Double tap to reset the reference point to the center of the screen.
- Press the track button to link the reference point, center of screen, and current position.
- Press the location button to move the screen to a specific location.
Personal Black Box maintains three internal, geographic locations:
- The current position (when available); and
- The center of the screen.
These three locations are linked together when the Personal Black Box starts. Whe the position changes, the contents are scrolled so that the current position is centered in the screen and the geographic reference point changes to the center of the screen. The reference point change causes the chart to rotate so you may see rippling in the display.
Scrolling temporarily breaks the link between threse three points. With the link broken, the current position will update without changing the screen center or reference point.
Use a pinch gesture to zoom the contents. Zooming outwards increases memory and processing demands as more chart images have to be displayed. Extreme zooming is not recommended. Personal Black Box automatically zooms in if it detects memory problems.
Personal Black Back displays a gray screen when it is outside the chart coverage area. This could happen when using a Personal Black Box version with U.S. charts in Asia with position tracking. You can use the button to select a location within the covage area. If you scroll into an area that has not been drawn yet, this will be gray too. However, Personal Black Box will soon draw into these reas
Personal Black Box displays off white for areas generally within its coverage that ar do not have chart coverage. You scroll to get back into a coverage area, use to get to a specific location, or use to get to the current location.
The airplane indicator shows the current location on the display. The direction of the nose indicates the course, when that location information is available.
Geographic Reference Point
The geographic reference point is the location used as the origin for positioning the charts on the screen. Personal Black Box orients the charts so that the line of longitude through the reference point is vertical. Charts that are a distance away from the reference point may have visible splits among them. At the extreme, these are off white areas where the charts have pulled apart. In lesser cases, the features do not match across chart segements. This is a natural consequence of projecting a sphere (the Earth) on to a sheet of paper. You can eliminate splits in the area you are viewing by moving the geographic reference point closer.
There are three ways to move the geographic reference point. First, as described above, the button links the geographic reference point to the current location. When linked, Personal Black Box continuously moves the geographic reference point to match the current location. Personal Black Box automatically updates the geographic reference point to the center of the screen after a few second of inactivity.
Here is an example of a split. The reference point for the image on the left is San Francisco. By the time the chart mosaic extends out to Illinois, the images stay joined at the sides but split apart at the top and bottom. The image on the right shows how the reference point has moved to to Missouri.
The split separation becomes noticeable before the actual split. Here is a zoom in from the above where you can see that the Deming airport occurs in two locations because the charts do not overlap. Keep reference point close to your view area and you will not have a problem.
There are a few places where charts do not overlap the adjoining chart. In that case you will see a narrow strip of off white. If the shapes above and below these strips are aligned, you do not need to change the geographic reference point. This image below shows an example. The lines are aligned perfectly but there is a small gap between two charts. Changing the reference point does not correct this.
Changing the Location
You can move the display to a major airport by tapping the button. This displays a list of airports. You can scroll through this list. Tap the airpoint you want to go to it. This will center the airport and makes its location the reference point.
To dismiss the location selection, simply tap outside the list.
Personal Black Box uses the airport's published reference point as its location. This may not be at the center of the airport so the airport may not be centered within the blue reference point circle.
Personal Black Box displays its status in the upper left corner of the display.
X kts Y MSL: Traveling at X knots at Y feet above mean sea level:. This is the normal display when Personal Black Box is receiving location information.
No flight data available.: No location information has been recevied from the device.
Location services are restricted.: Location services are restricted on the device. Personal Black Box cannot get location information until the location settings are changed.
Personal Black Box is not authorized to use location services
Make sure the GPS is enabled and Personal Black Box is authorized to use location services.: Location services are available but Personal Black Box is not authorized to use them. The privacy settings on the device need to be changed to allow Personal Black Box to access the location.
Location services enabled. Waiting for location.: Location services have been enabled but a location has not been received from the device.
Airline flight tend to follow Jet Routes. These are highways in the sky defined by ground-based VOR beacons. VORs are indicated on the charts as hexagons surrounded by compass circles. The VOR compass roses indicate magnetic courses. Flights move from VOR to VOR along the numbered Jet Routes. Personal Black Box Jet Routes contains the Jet Routes for the continental U.S.
For visual navigation, use Person Black Box Visual. Its WAC charts show Victor Airways that are used for flights below 18,000. Sometimes Victor Routes underly Jet Routes but, for the most part, they do not. When trying to determine your position, it is best to ignore the Victor Airways.
Airports in blue have control towers and airports in magenta do not. This distinction is not useful for visual navigation. Size tends to be more important. The airports with runways drawn within circles, have runways under 8,000 ft long. Those drawn without circles have runways longer than 8,000 ft. The larger airports tend to be easier to spot from the air. Keep in mind that airports with medium runways lengths (5,000 to 7,000 feet) tend to be easily visible.
When you spot an airport:
- Does the airport have terminals and parking lots. If not, it will be a general aviation airport.
- Does the airport have large expanses for aircraft parking. If so, it is likely to be an military field.
- Count the number and positions of the runways. The runway layout is the best way to identify a specific airport. Compare the runway pattern and orientation you see to the chart in Personal Black Box Visual.
Due to the prevailing winds, airports in the same area often have similar runway layouts. For example, the runways at Ft. Lauderdale, Opa-Locka, and Miami Airports are similar. Seeing this same pattern at three airports puts you in Southern Florida.
The charts in Personal Black Box Visible show major roads. Use roads in conjunction with other landmarks. The indication of roads tends to be inconsistent in aviation charts. In built up areas, only multi-lane, divided highways are shown. In rural areas, two-lane roads are indicated. Roads alone, tend to be misleading indicators of position. Roads in combination with other landmarks are very useful.
Lakes tend to be good indicators of position, especially man-made lakes. Natural lakes tend to have rounded shapes while man-made lakes tend to be tree like. The orientation of the branches and the position of the dam are especially useful for identifying you location.
In the U.S. above 18,000 feet, aircraft fly at flight levels. A flight level is an area of constant pressure, not actual altitude. An aircraft at Flight Level 330 is flying at the pressure level that would occur at 33,000 feet under standard conditions. Personal Black Box reports the altitude as the best calculation above mean sea level. It is normal for the reported altitude to be different from the cruising altitude for the flight because they are two different measurements.
The big problem creating a map is how to put a the spherical surface of the Earth on a flat sheet of paper. Over the centuries, various projections have been developed to map the Earth to paper. The simplest projection is Mercator. Mercator maps project the sphere of the Earth on to a cylinder. One advantage of Mercator projections is that the lines of latitute and longitude form grids so that the map can be divided into tiles. The ability to tile makes Mercator projections easy to work with in computers. Google Maps and most other mobile map applications use Mercator maps. There are several drawbacks to Mercator projections. The more closer they move to the poles, the more distorted the shapes become. Greenland becomes larger than Africa in Mercator projections. What looks like a straight line going West-East on a Mercator map tends to be a highly curved path. The distortions in Mercator maps are great over the long distances that aircraft operate.
Aviation charts use a different type of projection: Lambert Conformal Conical. This projects the features of the Earth on to a cone that intersects the sphere at two circles. Advantages over Mercator projections include the shape distortions are much less, angles correct, and paths are much straighter. There is no distortion in the vicinity of the intersecting circles. The down side is that Lambert projections are much more difficult for computer applications to work with.
Personal Black Box creates a mosaic from the available charts. The first step in drawing is to identfy the reference location. Peronal Black Box positions each chart segement in the correct location relative to the reference location. Then the chart is resized and rotated so that they will fit together. The process of positioning charts is rather complex.
The various avaiation charts use different projections. Lambert charts have no distortion near the two circles where their projection intersects the globe. Charts use different intersections so that the area visible on a specific chart will have as little distortion as possible.
The problem this causes for an application is that Lambert charts do not fit together globally. If two charts are projections on to different cones, they cannot be made to line up correctly everywhere. The solution Personal Black Box uses is to have a moveable reference point. In the general vicintly of the reference point, the charts line up very closesly. By moving the reference point, you can always make the charts line up in the area you are intersted in looking at. The charts tend to line up well East-to-West. This is because the charts at the same latitude use the same or close to the same cone for projection.
As described previously, chart segments that are a long distance (usually more than 500 miles) from the reference point tend not to fit together vertically. When chart X is aligned with Y and chart X is aligned with Z, charts Y and Z might not align with each other. This is because charts within a different zones of lattitude are projected on to different cone.
Personal Black Box does share any data with us. Whatever you do with Personal Black Box is private.