How CaptainVoice works
CaptainVoice is an iPhone app. It records the aircraft intercom, the GPS track, barometric altitude, motion and, if you carry one, an ADS-B receiver. Everything from one flight goes into one Flight Log. Here is what happens from preflight to debrief.
Before the flight
Connect the intercom
Plug a USB-C audio adapter into the iPhone. Run a cable from the intercom's recording output into the adapter. On the Preflight screen the audio row shows the adapter's name in green, and the level bar moves when people talk. The gear page lists what you need.
No adapter? CaptainVoice records with the iPhone's own microphone and shows "Built-in mic" in yellow. It never stops you from starting, but ATC and the intercom will be faint.
Preflight
Choose Flight, the aircraft and the crew, and mark who is PIC. The screen also shows GPS, sign-in, network and how many minutes of recording the battery has left.
Before you record anyone, get their OK. The app reminds you under Crew.
For a ground lesson, choose Ground instead. It records the room with the iPhone's microphone, or an outside microphone you pick.
Slide to record
Slide the bar to start. CaptainVoice never starts or stops on its own.
In flight
Recording in the background
Switch to ForeFlight or any other app. CaptainVoice keeps recording behind it: the intercom, the GPS track about once a second, barometric altitude, motion when the iPhone is mounted, and ADS-B data from a Stratux or Sentry on the cockpit Wi-Fi. It mixes with other apps' audio and plays no sound.
Pilot Marks
Tap MARK, or anywhere on the recording screen, at any moment you want to find later: a question for the debrief, a nice landing, a readback that went sideways. Each Pilot Mark is saved in the Flight Log with its time.
A Pilot Mark button on the Lock Screen and in Control Center is coming.
Status at a glance
The recording screen has a status strip: Audio, GPS, ADS-B, Upload and Battery. A cell turns yellow or red when something needs you, with a banner such as "AUDIO LOST: check USB adapter".
A few silent notifications cover the rest: audio lost for 10 seconds, recording on the iPhone microphone, GPS lost, and about 20 minutes of battery left. No sounds.
A Day/Night switch turns the screens red for night flying. It comes on by itself after sunset.
Upload every 15 seconds
The Flight Log is cut into Chunks of 15 seconds. Each Chunk is saved on the phone the moment it closes, then uploads over cellular or Wi-Fi when there is signal.
No signal? The screen says "Saved on device" and how many Chunks are waiting. They upload when the phone finds a network, in the air or after landing.
If the app crashes or the battery dies, you lose at most about 15 seconds. When you open the app again, it offers to resume the same Flight Log.
A phone call, Siri or an unplugged cable can interrupt the audio. CaptainVoice starts again by itself and records a Gap with the reason and the length, so a silence is never a mystery.
After landing
Stop and the summary
Hold STOP for 2 seconds. The summary shows the aircraft, the crew, the times, your Pilot Marks, any Gaps, a note on audio quality, and the upload all the way to "chain verified".
Share the flight
"Share recording and track" turns the flight into ordinary files: the audio (.m4a), the GPS track (.gpx) and an info sheet. Send them by AirDrop, Messages, Files or Google Drive. It uses the phone's own copy, so it works without signal.
Transcript
After the flight uploads, the audio can be transcribed in the cloud with speaker labels (by AssemblyAI). During the beta we release each flight for transcription by hand. The transcript will show next to the audio on the replay page.
The Debrief (coming)
The full Debrief is coming to the website: a map with the Track and a playback cursor, an altitude profile, a timeline with takeoffs, landings, Pilot Marks and Gaps, and an audio player with the transcript, all linked. Tap a Pilot Mark and the audio plays from there. You'll also be able to download the audio, the track (GPX, KML) and the transcript.
Proof the recording wasn't changed
A recording is worth more when you can show nobody changed it. Here is how CaptainVoice shows that a Flight Log is complete and unchanged.
- A Hash Chain. Every Chunk carries a digital fingerprint (a hash) of its own content and of the Chunk before it. Take a Chunk out, add one, or change a single second, and the fingerprints stop matching.
- A signed Manifest. At Stop, the phone writes a Manifest: how many Chunks there are and the last fingerprint. It signs the Manifest with a key that stays in the iPhone's Secure Enclave and can't be copied off the phone.
- A check on our server. The server checks the chain as Chunks arrive, and the signature when the Manifest arrives. When everything matches, the app shows "chain verified".
This is tamper evidence: it shows whether the Flight Log was changed after that phone recorded it. It does not make CaptainVoice a certified cockpit voice recorder.
Coming: a public proof page for each flight, opened with its proof code, that shows it is complete and unchanged, with no audio and no names. An examiner, an insurer or a school can check a flight without hearing it.
Coming to the website
The website at captainvoice.com is being built in stages. None of the following is available yet.
- Live View. Off until you turn it on. Then you, the Watchers you add by email, and anyone you send a Share Link can follow the flight on a map: the Track so far, altitude, ground speed, Pilot Marks, nearby ADS-B traffic, and the audio about 20 to 40 seconds behind. A line says how fresh the data is. The map is not for navigation.
- Flight Alerts. Red and yellow alerts in Live View, from the flight data (for example a fast descent close to the ground) and, if you also turn on Word Watch, from danger words such as MAYDAY, PAN-PAN or "squawk 7700". Word Watch keeps only the matches, never a transcript. Alerts can miss real events and raise false alarms. CaptainVoice is not an emergency service. If you think there is an emergency, call 911 or the ATC facility.
- Replay and sharing. Your flight library, the Debrief on a big screen, downloads, and Share Links so a student can review a flight at home without the app.
- Logbook. An entry drafted from each flight: date, aircraft, airports, total time, landings, night and cross-country. Each value is marked Detected or Corrected, and what CaptainVoice can't measure stays empty, not zero. Totals, currency, and exports for ForeFlight, MyFlightbook, LogTen, a spreadsheet and a PDF.
- ACS Practice. Tag a moment or a stretch of a flight with an ACS Task, and see what you've practiced for Private, Instrument and Commercial. "Practiced" or "not yet practiced", never a grade.
- Instructor Signatures and Endorsements. Instructors sign training entries and AC 61-65 endorsements with a passkey (Face ID or Touch ID). A signed entry is locked, and a change becomes a new signed Amendment. Built to follow AC 120-78B.