Flight reference · iPhone & iPad
An iPhone attitude indicator in flight: know your readings.
A horizon, a heading, a changing altitude. AirHorizon brings readings from your phone onto one screen, so you can observe them together.
Use it as a supplementary reference display. Here’s what each reading means, how to set up the phone, and why its numbers may differ from the aircraft’s instruments.
For observation and reference only. Do not rely on the phone to fly or navigate, or as a backup if an aircraft instrument fails.
Understand the display
One screen. Different sources.
An attitude indicator is also called an artificial horizon. The horizon is the centre of AirHorizon’s display, but the surrounding numbers do not all come from the same sensor. Knowing the source makes the screen easier to interpret.
Pitch and roll: the phone’s orientation
The horizon uses the device’s motion sensors. Pitch shows an up-or-down angle; roll shows tilt to either side. Move the phone in your hand and you change its reference. A fixed mounting position and calibration matter.
Ground speed: movement over the ground
In standalone mode, speed comes from the device’s location data. It is ground speed, not indicated airspeed. Do not expect it to match the aircraft’s airspeed indicator or use it to judge a stall margin.
Altitude: check the selected source
AirHorizon offers GPS and barometric altitude where supported. The barometric option can fall back to GPS. Relative Altitude makes a chosen reading the local zero; it does not measure clearance above the terrain.
Heading: check the reference
True (Auto) uses true north when available and falls back to magnetic. MAG identifies that fallback; Magnetic Only uses the magnetic reference. Nearby magnets and metal can affect compass readings.
Variometer: a climb or descent trend
The variometer combines device motion with the selected altitude source. Smoothing reduces noise but introduces a response delay. Optional sound makes the trend audible. Its response and sensitivity settings change how that trend is presented.
The app is free to download. Heading, speed and altitude displays, the visual and audio variometer, and external simulator telemetry require AirHorizon Pro. Available readings also depend on your device’s sensors and permissions.
Another view from a flight
From the passenger seat
Watch AirHorizon beside an airliner window as altitude and ground speed build during the climb. The outside view gives context to the changing numbers on the screen.
Keep the selected altitude source in mind when interpreting a reading; the notes on sources and limitations explain why it may differ from an aircraft instrument.
Before you use it
Set up while you’re on the ground
Get familiar with the screen before a flight. Put the phone in its intended orientation, open the app, and watch what changes as you gently tilt it.
- Choose a stable position. Keep the device secure, clear of controls and your view. Select portrait or landscape before calibration.
- Check permissions and sources. Allow the motion and location access needed for the readings you want. If you previously used a simulator, check Settings → External Source and return the selected channels to the device.
- Align near level. Use ALN to set the horizon reference for the mounting position. Large calibration angles can reduce accuracy. Calibration changes the reference; it does not verify flight accuracy.
- Check units and altitude mode. Choose the speed and altitude units you expect. Check Altitude Source and whether Relative Altitude is enabled before interpreting a number.
- Make the screen readable. Adjust the layout, brightness and contrast. Try variometer audio on the ground if you plan to use it, and keep it from distracting you or masking communications.
Finish adjustments before departure. Keep aircraft operation and the outside view ahead of interacting with the phone.
When two displays disagree
Start by asking whether they show the same quantity. Ground speed and airspeed differ. Relative altitude and an aircraft altimeter use different references. True and magnetic heading can differ too.
Even matching labels do not establish matching accuracy. Acceleration, vibration, magnetic interference, signal loss and device movement can affect phone readings. Pressure readings reflect the pressure around the device; cabin pressure changes can affect a barometric display.
A reference display has a defined role
Observe the readings and learn what they represent. Use the aircraft’s instruments and established procedures for flight decisions. AirHorizon is not a certified aviation instrument and must not serve as a primary or backup attitude reference.
Agreement during one part of a flight does not validate the phone for every manoeuvre or condition. A smooth animation, calibration, or a flight video is not evidence of dependable backup performance.
A few practical questions
Do I need a separate receiver?
No separate receiver is needed for AirHorizon’s standalone mode. It uses the sensors and location data available on the iPhone or iPad. Device capabilities vary; some iPad models have no built-in GPS, and barometer availability also varies.
Can I use the phone if the aircraft’s attitude indicator fails?
Do not rely on AirHorizon for that role. Its supplementary reference display is for observation, not an emergency substitute. Follow the aircraft’s procedures and use the equipment intended for that purpose.
Why does the horizon change when I move the phone?
Standalone attitude comes from the phone’s motion sensors. Moving the phone changes what they measure, even if the aircraft has not changed attitude. Check the mounting position and set the reference on the ground.
Questions about a reading or setting? Ask the developer. Include your device model, app version and selected data source.
Start with the display
Get to know your pocket reference.
Try AirHorizon on the ground, explore the layout, and learn which readings your device can provide.
Get AirHorizon on the App StoreFree download · Additional displays require Pro · For reference only
Also fly at a desk? As an additional feature, AirHorizon Pro can receive simulator telemetry. Our X-Plane 12 connection guide covers that separate setup.