2.0.1 is a tuning release. Everything in it is about the instruments moving continuously rather than a sample at a time. THE COMPASS STRIP TURNS SMOOTHLY On the move the display shows ground track rather than heading, because a magnetometer surrounded by metal is not worth trusting. That track came straight from the GPS course — published once a second, in whole degrees — so the strip stepped a whole second of turning at a time, and the faster you turned the harder it jumped. The track is now carried on the gyroscope between fixes and each course is worked in gradually, so a turn sweeps instead of ticking. THE SPEED TAPE STOPS WHEN YOU DO Coming to a standstill, the tape used to keep counting down for a second or more after the vehicle had actually stopped. It now reaches zero as you stop. SPEED COMES FROM THE ACCELEROMETER Ground speed is now derived almost entirely from the accelerometer, with the satellite fix only trimming it rather than driving it. The reference the acceleration is measured against was rebuilt so that a long brake can no longer wash it out, and the mounting angle is recalibrated automatically every time you come to a standstill — so the tape is at its most accurate exactly where it used to be at its worst, in stop-and-go traffic. DRAWN AT FULL REFRESH RATE Both tapes and the compass strip are now drawn from the current model state at the display's own refresh rate, rather than only when a sensor reading happens to arrive.

Version 2.0 is a complete rewrite. The instrument looks the way it always has — same layout, same colours, same tapes. Everything behind it is new. THE HORIZON CAN BE TRUSTED IN A TURN An accelerometer cannot tell gravity from centrifugal force. Version 1 read one directly, so rolling into a turn quietly brought the horizon back towards level, and taking a bend on the ground tilted it when you were not banked at all. Attitude now comes from the gyroscope, with the turn worked out of the reading using GPS ground speed. Bank into a turn and the horizon shows the bank you are actually flying. Accelerating down the runway no longer pitches the nose up. Pitch is exact too. Version 1 used a linear approximation that over-read by half again near level — a three degree climb attitude showed as nearly five. A REAL ALTIMETER Altitude comes from the barometer with your own altimeter setting applied, not from GPS height. Set it in inches or hectopascals, drop to standard 29.92 with one tap, or match it to your GPS altitude. Negative altitudes read correctly, for fields below sea level and for standard pressure on a high day. Devices without a barometer fall back to GPS and say so on screen. VERTICAL SPEED THAT ANSWERS IMMEDIATELY Vertical acceleration is blended with the barometer, so the needle moves in a fraction of a second rather than lagging behind a once-a-second pressure reading — and it still cannot drift. NOTHING TO SET UP Down is simply where gravity points: hold the device upright and the horizon is level. If your cradle holds it at an angle, fly straight and level and press TRIM once. Works in landscape and portrait, on iPhone and iPad, and turning the device in its holder rolls the horizon without disturbing the pitch. NEW ON THE DISPLAY • Rate of turn, so you can fly a standard rate turn • Six-second trend vectors on the speed and altitude tapes • Selected altitude, with a bug on the tape and a fine deviation scale • Compass ribbon with a heading bug • Speed tape arcs you can set to your aeroplane — presets for the C172, PA-28, DA40, SR22 and gliders, or enter your own V-speeds • Optional G load display • Classic and Glass colour schemes • A live sensor page showing every raw value DEMO FLIGHT Settings has a demo that flies a circuit from the runway: take-off roll, climb out, a steep turn, and back down to land. It is a genuine flight model rather than an animation, so the instruments agree with each other — roll into the steep turn and watch the load factor rise and the speed decay with it. A good way to see how everything works without leaving the ground. PLEASE NOTE The speed tape shows GPS ground speed and is labelled GS. Version 1 called it TAS; it never was, and there is no pitot tube in an iPhone. This is a training and situational-awareness aid built on consumer sensors, not a certified instrument. Never use it as a primary reference for aircraft control or navigation.

* ADDED: GPS Mode! When you start the app your iPhone will now ask if you want to allow use of your location. If you choose no, you will be in the previously known "mockup mode". * ADDED: In GPS Mode you will get air speed, rate of climb, heading and altitude updated from the very accurate iPhone GPS. * CHANGE: Because course and speed where only introduced in SDK 2.2 as part of Core Location this program will now require OS 2.2 or higher. Our tests have shown that those two new OS features by far surpass all previous workarounds in accuracy and responsiveness. Therefore we decided to make OS 2.2 the minimum requirement. * CHANGE: In order to support GPS Mode (by popular demand) we have to discontinue support for iPod Touch. * FIXED: Minor tweaks to improve the "mockup mode". Altitude and Speed are now limited to sensible numbers. Please don't hesitate to send us your suggestions.