Class Delta
Privacy Policy
Last updated 2026-11-02.
Class Delta is an iOS app built by aviation enthusiasts ("we", "us") that records your aircraft's radio and intercom audio, alerts you when air traffic control calls your callsign, replays recent calls, and, if you turn on cloud backup, keeps your recordings in our cloud. This policy says what the app collects, what leaves your device, why, who else handles it, how long it is kept, and how to delete it.
The short version: recording needs no account and nothing leaves your device unless you turn on "Upload to cloud". With it on, your recordings are stored in our cloud as a backup you can restore on another device, and they are also used to train and improve the models behind the app. You can delete any flight, or your whole account, from the app at any time.
1. What the app records and keeps on your device
- Audio. Everything your headset hears while recording: the radio and the intercom, which includes the voices of anyone aboard. Recordings are saved on your device in five-minute pieces as they happen.
- Location. Your GPS track during a recording, so a flight can be shown on a map and tied to the airports and frequencies you used. Location is used only while recording.
- What the app heard. The calls the alert spotted and where it split transmissions, as produced by the speech and voice models that run on your device. Speech recognition for the alert happens on the device; no audio is sent anywhere for it.
- Your aircraft. The tail numbers, type words and telephony callsigns you enter so the alert knows what to listen for.
- A technical log for each recording: when recording started and stopped, interruptions, audio route changes (for example "USB" or "Bluetooth", not the name of the device), battery and thermal state. It exists to diagnose a recording that went wrong.
All of this stays on the device, under your control, in the app's own folder.
2. What leaves your device, and when
Nothing, unless you sign in and turn on "Upload to cloud". Before it turns on, the app shows a consent screen with the points below and records the version and time of your agreement.
With it on, each finished recording uploads over Wi-Fi: the audio, the GPS track, the technical log, the recording's manifest (start and end time, duration, any name or notes you gave it), and what the app heard. Uploads use an encrypted connection and are stored encrypted at rest.
Also sent to our server when you sign in: an identifier for your account (from the sign-in provider, see section 5), a random identifier for the app installation, your device model, iOS version and app version, and the consent records above. We use these to tie uploads to your account, to sync deletions across your devices, and to diagnose problems.
Before every recording the app asks you to confirm that you are alone or that everyone aboard has agreed to the recording and to the uses in this policy. The time of that confirmation is stored in the recording's manifest and uploaded with it.
3. Why we use your recordings
- To provide the service to you: backup, restore on another device, and the post-flight debrief once it exists.
- To train, evaluate and improve the models behind the app, such as spotting calls to your callsign, splitting transmissions, and recognizing radio speech. People working on the models (today, the developer) may listen to uploaded recordings and label what is said and by whom.
- To diagnose problems you report, using the technical log and, if you tell us which flight, the recording itself.
- To answer a deletion request from someone who says they were recorded without consent.
We do not use your recordings for advertising. We do not build or store a voiceprint of you: the app tells voices apart within a recording, and your own voice is marked only by labels you or we attach to pieces of that recording.
4. Who else handles your data
We use a small number of service providers, each acting on our instructions:
- Cloudflare hosts our server, stores the recordings (R2 object storage) and the account database (D1), and delivers this website.
- Clerk handles sign-in. It holds your email address and the identifier it receives from Apple or Google, and issues the tokens the app uses to talk to our server.
- Apple or Google, if you sign in with them, under their own privacy policies. With Sign in with Apple and "Hide My Email", we see only the relay address Apple gives us.
- Apple also provides TestFlight and the App Store, which collect crash and usage data under Apple's terms if you have allowed that in your device settings. We do not run our own analytics or crash reporting in the app.
We do not sell your recordings or any other data about you, and we do not share them with anyone else except as the law requires: for example a subpoena or court order, in which case we will tell you unless we are prohibited from doing so. If the business is ever sold or merged, recordings would pass to the new owner only under this policy or one at least as protective, and you would be told.
Our servers and storage are in the United States. If you use the app from elsewhere, your data is transferred to and processed in the United States.
5. How long we keep it
- Recordings stay in our cloud until you delete them. There is no automatic expiry.
- Deleting a flight in the app removes its audio, files, name and notes from storage at once; a small record of the deletion (the flight's identifier and the time) stays so your other devices learn of it and stop showing the flight.
- Deleting your account removes every recording, every file, your consent records and your devices from our systems, and asks Clerk to delete the account. A marker with your account identifier is kept so an old sign-in token cannot recreate the account.
- Models already trained on a recording are not retrained when the recording is deleted. They do not contain the recording, and we do not use them to reproduce it.
- Labels and derived data (transcripts, speaker labels, scores) made from a recording are deleted with it.
- We keep no separate backups of recordings. Our database provider keeps a rolling 30-day history of the account database for disaster recovery, so a deleted record (not the audio) can exist there for up to 30 days after deletion.
6. Your choices and rights
- Record without an account. Recording, the alert, say-again and playback work with no sign-in and no upload.
- Turn uploads off at any time in Cloud settings. Recordings already uploaded stay until you delete them.
- Delete a flight from this device, from the cloud, or everywhere, from the flight list.
- Delete your account in Settings.
- See what we hold or ask a question: email hello@classdelta.app. We answer within 30 days. Residents of California, Washington and other states with privacy laws have the rights those laws give them (access, deletion, correction, no discrimination for using them); the above is how we meet them, and we do not sell or share personal information in the sense of those laws.
- If you were recorded aboard someone else's aircraft and did not agree, email hello@classdelta.app with what you know about the flight; we will find and delete the recording and may suspend the uploading account.
7. Children
The app is for pilots aged 18 and over, or student pilots of at least 17 whose account is held by an adult. We do not knowingly collect data from anyone under 17; if you believe we have, email us and we will delete it.
8. Security
Uploads travel over TLS and are stored encrypted at rest. Access to the storage and the database is limited to the people who need it to run the service and work on the models, through named accounts, and every server request is authenticated with a short-lived token from the sign-in provider. No system is perfectly secure; if a breach affects your data we will tell you as the law requires.
9. Changes
When this policy changes in a way that matters, the app shows the new version and asks you to agree again before uploads continue. The date at the top is the version in force. Older versions are available on request.