11. GPS HUD

_images/fig_gps_hud.jpeg

Image 11.1 GPS HUD

The GPS HUD appears across the top of the Map Page. With no plan selected there is only one row of fields (6 on the iPad or 3 on the iPhone.)

When you begin to plan, the GPS HUD converts to a two row display. The plan is now active and if desired can track your position on the map and update the GPS HUD fields with information such as Track, Ground Speed, Distance To Go, etc. The far right bottom box is the ‘Cancel’ box which, if tapped, will exit the current plan. By default only a single tap is required, however there is an option in the Preferences section of the Settings page called ‘Double-tap HUD’ which when enabled requires a double tap on the Cancel button. This can be handy for turbulent conditions.

If you don’t want the GPS HUD displayed tap the Map View Options button and turn off ‘Show GPS HUD’. A long press on any of the GPS HUD boxes will bring up a list of available fields. Tap an item in the list to switch the GPS HUD box to the selected data option.

A single tap (or double tap if that setting is enabled) on one of the HUD boxes will open a larger popup showing that field on the main map display. That popup may be dragged around to reposition it, and is retired with a double tap or by tapping the red cross in the top right. These boxes remain on the map until dismissed even if the GPS HUD is turned off.

Some data requires an accurate GPS signal (think GS, ETA etc.), or an internet connection (QNH, TMP). If data is not available due to lack of GPS signal or internet connection then ` - - ` will be displayed.

In the top right corner of the GPS HUD there is a small coloured dot. This is explaines below in GPS Accuracy Dot

11.1. HUD box options

Tap and hold (long press) on any GPS HUD field and a popup will result displaying various option as described below:

BRG (FROM)

Bearing from the last waypoint

BRG(TO)

Bearing to next waypoint

BULLSEYE

Bullseye set on waypoints. The Bullseye feature is described in Special Features chapter

CDA

Current Density Altitude, based on GPS Altitude

COM

Compass. Note: Tapping the compass HUD box does not bring up a map overlay version

CRSR BRA

When the cursor is enabled, this will display the position of the cursor location in reference to your current position

CRSR BULL

When the cursor is enabled, this will display position of cursor in reference to the set Bullseye

CTA LL

Lowest Level CTA step for current GPS position (CTA must be ticked in Map View Options → Airspace)

CURSOR

Shows the coordinates of the cursor position in either Degrees Decimal Minutes (DD MM.M), or Degrees Minutes Second (DD MM SS) format

DA

Relative Density Altitude (either at nearest aerodrome or user set)

DFW

Distance from last Waypoint

DTG

Distance remaining until reaching next waypoint (great circle distance)

ETA

Estimated Time of Arrival at next waypoint

ETA(DEVICE)

Estimated Time of Arrival at next waypoint, displayed in local time (as per the device timezone)

ETA(LAST)

Estimated Time of Arrival for the final waypoint in the plan

ETE

Estimated Time Enroute

FIA

Area frequency (Class G) based on your current GPS position

FIA E

Class E airspace area frequency based on current GPS position

FIA NEXT

Next Class G area frequency based on your current heading

FIA/NXT

Current and next Class G area frequency combined into one box

FL

First Light at your current position

GCB(TO)

Great Circle Bearing to the next waypoint. When this option is selected the app will display the Great Circle (curved) track for your plan as a grey dotted line, in addition to the standard magenta track.

GPS ALT

Altitude according to the device GPS source

GPS Error

Displays the current GPS error as calculated by the device. The lower this is, the better fix you have. Normally it is around 10m. It can be used to give you an indication of the best place to position your iPad in the aircraft.

GS

Ground Speed in the units selected for the aircraft profile in use

HAG

Height Above Ground based on GPS altitude and the current terrain altitude to estimate your height rather like a synthetic ground radar. As the terrain data is on a 900 metre grid, this can be in error for rapidly changing terrain (i.e. a cliff face)

HSI

Horizontal Situation Indicator. A mini version of the HSI is displayed. At the bottom of the mini-HSI a ‘t’ bar indicates deviation left or right of track. The arrow indicates the bearing to the waypoint to which you are tracking. Tap once to see full sized HSI display on map page which is described in further detail below.

LAT

Current GPS latitude

LAT/LON

Current GPS latitude/longitude consolidated in one box

LCL

Local Time (device timezone)

LL

Last Light for your current GPS position

LON

Current GPS longitude.

LSALT

Lowest Safe Altitude. Displays the Airservices Grid Lowest Safe Altitude for your current GPS position

NZ FREQ

Displays the relevant New Zealand OCTA MBZ/CFZ/FISCOM frequency for your current GPS position

NZ FREQ NXT

Displays the next relevant New Zealand OCTA MBZ/CFZ/FISCOM frequency based on your current heading

QNH

Displays the SmartBrief QNH for the nearest airport with a METAR service. If the SmartBrief database is more than 1 hour old ‘– –’ will be displayed.

Warning

OzRunways HUD box QNH is not an approved source of actual QNH.

SELF BULL

Displays the bearing from your current position to the set Bullseye

SUNSET

Sunset time at your current GPS position

TDR

Total Distance remaining to the next landing point in your plan

TMP

Temperature at closest METAR location

TRK

Current GPS track

TRN

Turn Indicator

UTC

UTC (Zulu) Time

VS

Vertical Speed

XTK

Cross Track Error

11.2. Horizontal Situation Indicator (HSI)

The HSI is a special case, in that when selected as a GPS HUD field, a small display is shown. A single tap (or double tap if that setting is enabled) on a HUD box containing the HSI results in a fully fledged HSI being displayed on the map as shown on the left in Image 11.2

_images/fig_gps_hud_hsi.jpeg

Image 11.2 (Left) traditional HSI view (Right) HSI range view

The yellow arrow (and text) is the GPS track. The purple arrow is the course to the next waypoint. There is an orange bug that can be tapped, held and moved to set a direction (i.e. a runway direction for situational awareness). The green text is the destination name and distance. The figure above shows a view of the HSI where the aircraft has drifted left of track. This is indicated by the misalignment of the arrows and indeed the values reported on the HSI. The dots in the centre of the HSI represent 2 degrees per dot.

Tap three times on the HSI to see a 70 degree view ahead of your track (as shown on the right in Image 11.2). Range buttons in the bottom left and right (+/-) can be used to increase or decrease the range, which is shown in green at the top left. ADs and ALAs are shown in their relative position and distance. Three taps gets you back to the original HSI display.

11.3. GPS Accuracy Dot

In the top right corner of the GPS HUD there is a small coloured dot. The colour of the dot gives a quick visual indication of horizontal GPS accuracy as follows:

Green: Good accuracy, 30m or less

Yellow: Poor accuracy, between 30m and 200m

Magenta/purple: Very poor accuracy, between 200m and 5km

Red: No GPS signal

If horizontal GPS accuracy is worse than 200m (i.e. a magenta or red dot) OzRunways will no longer display your location on the map, other data in the HUD that relies on GPS position may no longer function. If this happens, check that OzRunways has the approproiate permissions to access location services in the device settings. You may need to move the device to a different location in the aircfaft away from any obstructions.