Melisa handles language and context
Talk naturally, ask about the flight, use supported voice commands, and bring SimBrief or weather context into the conversation.
AI FIRST OFFICER · PMDG 737-800 · MSFS 2024
DOCTORFO
AI that understands. Aircraft control that stays deterministic.
Melisa can talk with you, understand supported voice commands, use flight context and explain what is happening. But the AI never directly controls the aircraft. Every supported cockpit action is routed through specifically programmed and tested DoctorFO functions using the PMDG SDK / SimConnect.
Stable working integration available now for the PMDG 737-800 in MSFS 2024.
The public 24-hour trial is Core-only. Melisa AI Voice and FMC AUTO are Full-version features.
AI for understanding and interaction
+
deterministic logic for aircraft control
WHY DOCTORFO IS DIFFERENT
The conversation engine and the aircraft-control engine are intentionally separated.
DoctorFO uses AI where AI is useful — understanding language, context and questions — while keeping actual simulator control inside a known, testable command layer.
DoctorFO decides what can actually happen
A cockpit action is executed only when it maps to a specifically programmed and tested DoctorFO function. The AI cannot bypass this layer and operate arbitrary simulator events.
The Captain stays responsible
DoctorFO is an assistant, not a replacement pilot. It helps with workload, context and supported procedures while flight decisions remain with you.
HOW DOCTORFO WORKS
Use DoctorFO with or without conversational AI.
The deterministic Core remains the foundation. Melisa adds a natural voice and context layer on top of the same tested aircraft functions.
DoctorFO Core
Use the on-screen controls or the remote panel to run tested cockpit flows and automation.
- Cockpit flow buttons
- Engine-start and departure automation
- FMC Auto where supported
- iPad / iPhone Remote
- Deterministic aircraft control
DoctorFO + AI Voice
Talk naturally with Melisa and use supported cockpit voice commands while the same tested control layer operates the aircraft.
- Natural conversation with Melisa
- Cockpit voice commands
- Live flight context
- SimBrief-aware assistance
- Your own OpenAI API key required for Melisa
Melisa is more than a command interface: you can have normal voice conversations, ask about the current flight, SimBrief plan and weather, and still issue supported cockpit commands.
WORKING NOW
What the current DoctorFO build can help with.
These are current capabilities of the working PMDG 737-800 integration. Exact behavior remains limited to DoctorFO's validated functions and supported states.
Defined cockpit flows
Prepare for pushback, engine-start, before-takeoff and supported after-takeoff tasks using repeatable DoctorFO flows.
Flight-control commands
Supported LNAV, VNAV, autopilot, MCP speed and altitude, and flap commands through tested control functions.
Engine-start assistance
Aircraft-specific start sequencing is handled by programmed timing and state-aware logic rather than free-form AI.
SimBrief & weather context
Melisa can use supported flight-plan and weather context when discussing the current flight.
FMC Auto Setup
Validated FMC setup assistance can use current flight context while route decisions such as SID, STAR, runway and approach remain with the Captain.
Remote cockpit controls
Run supported DoctorFO Core functions from a touch-friendly iPad or iPhone panel on your local network.
NEXT MAJOR STEP · IN DEVELOPMENT
MELISA COACH MODE
Not just “do this” — help me understand what comes next and why.
Coach Mode is being designed for pilots who enjoy complex aircraft but may not yet know every 737 flow, switch or procedure. Melisa will use real aircraft state and flight phase to provide context-aware guidance without turning the aircraft into an arcade experience.
“What should I do next?”
“Why do we arm this?”
“Did I forget something before takeoff?”
Observe the real aircraft state
Use flight phase and relevant configuration to understand what is actually happening in the cockpit.
Explain important mismatches
Point out a meaningful configuration issue and explain why it matters instead of only announcing an error.
Offer a tested correction
When a supported correction exists, Melisa can offer it. The Captain approves first, and the same deterministic DoctorFO function performs the action.
Coach Mode is a roadmap feature and is not yet part of the current public production build.
SEE DOCTORFO IN FLIGHT
Watch the PMDG 737-800 demo.
See DoctorFO and Melisa working together in Microsoft Flight Simulator 2024.
Demo video on the FlyingDoctor YouTube channel. DoctorFO remains an independent third-party product.
WHAT DO I NEED?
Required vs optional.
REQUIREDFor DoctorFO Core
✓ Windows PC
✓ Microsoft Flight Simulator 2024
✓ PMDG 737-800 for MSFS 2024 (purchased separately)
✓ Internet connection for activation / online features
OPTIONALFor extra features
+ Your own OpenAI API key + active API billing for Melisa voice commands and conversation
+ SimBrief account for richer flight-plan context
+ iPad / iPhone for Remote Cockpit
DoctorFO Core does not require OpenAI. Melisa uses your own OpenAI API account; ChatGPT subscriptions do not include API usage, which is billed separately by OpenAI.
AIRCRAFT SUPPORT
Built around aircraft-specific integrations.
DoctorFO does not pretend every aircraft is the same. Each supported aircraft uses its own tested integration and workflow.
ACTIVEPMDG 737-800Current supported aircraft for Microsoft Flight Simulator 2024.
FUTURE / PENDINGAdditional aircraftAdded only after technical and licensing validation
DoctorFO communicates with the PMDG 737-800 through the PMDG SDK and does not modify PMDG aircraft files.
SETUP & FIRST FLIGHT
From purchase to your first DoctorFO flight.
Follow this one-time setup for Full V1.0: license, PMDG 737-800 SDK broadcasts, SimBrief, and (if you want Melisa voice commands/conversation) your OpenAI API key and audio devices.
Already purchased DoctorFO?
Do not download the Free Trial. After checkout, use the Full DoctorFO V1.0 download provided by Lemon Squeezy and activate it with the unique license key from your order.
Trying DoctorFO first?
Use the separate 24-hour Core Trial from this site. The Trial and Full V1.0 are different downloads.
Download the correct package
Paid customers use the Full V1.0 package from their Lemon Squeezy order. Trial users use the 24-hour Core Trial from this site.
Install and activate
Close DoctorFO and any DoctorFO/FlyingDoctor helper components. Run DoctorFO_Setup_V1.0.exe, launch DoctorFO from the desktop shortcut, then enter the license key supplied with your Lemon Squeezy order.
Enable PMDG 737 SDK broadcasts
This is a one-time PMDG setup required for reliable aircraft and CDU communication. Close MSFS 2024 before editing 737_Options.ini and make a backup first. If an [SDK] section already exists, edit that section instead of creating a duplicate.
[SDK]
EnableDataBroadcast=1
EnableCDUBroadcast.0=1
EnableCDUBroadcast.1=1Typical MSFS 2024 locations
Microsoft Store
%LOCALAPPDATA%\Packages\Microsoft.Limitless_8wekyb3d8bbwe\LocalState\WASM\MSFS2024\pmdg-aircraft-[737 variant]\work\737_Options.iniSteam
%APPDATA%\Microsoft Flight Simulator 2024\WASM\MSFS2024\pmdg-aircraft-[737 variant]\work\737_Options.iniThe PMDG folder name can vary by installed 737 variant; for the 737-800 it is commonly the 738 package. Save the file, then restart MSFS 2024.
Start in the right order
Start MSFS 2024, load the supported PMDG 737-800 into the cockpit and wait for the aircraft to finish loading. Then start DoctorFO and confirm PMDG CONNECTED before using aircraft automation.
Configure SimBrief and FMC AUTO
Open SETTINGS. Enter your SimBrief Pilot ID / Username; no SimBrief password is required. Generate a current SimBrief OFP before the flight. FMC AUTO starts OFF on every DoctorFO launch; enable AUTO only when you want to use it.
FMC AUTO handles only its validated setup scope. SID, STAR, arrival runway and approach / ILS remain the Captain’s responsibility.
Set up Melisa voice commands & conversation (optional)
Melisa is optional, but using Melisa voice commands or natural conversation requires your own OpenAI API key with active API billing/credits. ChatGPT subscriptions do not provide API credit. Paste your API key into SETTINGS. DoctorFO stores it locally for your Windows user using Windows DPAPI; it is not sent to the DoctorFO licensing server.
In our typical testing, Melisa AI usage has been around US$0.015 per flight (about 1.5 cents). Actual API cost varies with conversation length, model usage and OpenAI pricing.
Select microphone and speaker
In SETTINGS choose the correct Microphone and Speaker / Soundbar. Use REFRESH AUDIO DEVICES if needed. Echo-safe mode is recommended when using speakers or a soundbar. Save settings, then use TEST MELISA VOICE.
Stop Melisa before changing the voice or audio devices.
Run your first flight
Use the tested sequence: Prepare for Pushback → Start Engines / Ready for Taxi → Before Takeoff → Auto Mode / After Takeoff as appropriate. Use FMC AUTO only after PMDG and SimBrief are ready.
QUICK TROUBLESHOOTING
If a status is not ready…
PMDG not connected
Re-check the [SDK] block, confirm you edited the correct 737_Options.ini, restart MSFS, fully load the PMDG 737-800, then restart DoctorFO.
SimBrief not ready
Check the Pilot ID / Username, generate a current OFP in SimBrief, confirm internet access, then restart or refresh DoctorFO.
Melisa has no voice
Check the OpenAI API key and API billing/credits, Windows microphone permission, selected microphone/speaker, then run TEST MELISA VOICE.
FMC AUTO is waiting
Confirm PMDG CONNECTED, SIMBRIEF READY and the one-time SDK/CDU broadcast settings. FMC AUTO remains OFF by default on each DoctorFO launch.
Still stuck? Email support@doctorfo.com with a screenshot of the DoctorFO status area and a short description of what is not working.
YOUR FIRST FLIGHT WITH DOCTORFO
A full day in the right seat.
Your 24 hours start only when you activate the trial in DoctorFO.
- 24 hours of full DoctorFO Core access
- Core-only trial: AI Voice and flight-plan/FMC AUTO features are not included
- No payment card required
- Internet required at startup and during the trial for verification
- Windows 10/11 · Microsoft Flight Simulator 2024
- Supported aircraft and add-ons purchased separately. DoctorFO Remote is a separate optional add-on.
No external AI or flight-planning account is required for the Core trial.
DOWNLOAD 24-HOUR FREE TRIALAn independent third-party product; no Microsoft, PMDG, Fenix or OpenAI endorsement.
DoctorFO uses a privacy-preserving hashed device identifier to prevent repeated free-trial resets. The raw device identifier is not sent to DoctorFO.
The Core trial does not transmit microphone audio to DoctorFO or to a third-party AI service.
GET DOCTORFO
Try it before you buy it.
Choose the free trial or unlock the full DoctorFO license.
24-Hour Trial
Your 24 hours start only when you activate the trial in DoctorFO.
FREE DOWNLOAD 24-HOUR FREE TRIALThis is the separate Core Trial. Paid customers should use the Full V1.0 download from their Lemon Squeezy order.
Full License
One-time, perpetual license for the full DoctorFO desktop application. No subscription.
TRY 749.99 Buy DoctorFOOne purchase. Perpetual desktop license. No recurring subscription fee.
After payment, Lemon Squeezy provides the Full DoctorFO V1.0 download and your unique license key.
COMMUNITY RECOMMENDATION
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If you enjoy structured virtual airline flying, shared flights and meeting other sim pilots, take a look at Canada Air Virtual.
Independent community recommendation. Canada Air Virtual is not affiliated with or endorsed by DoctorFO.
Canada Air Virtual
Visit Canada Air Virtual ↗
SUPPORT & DOCUMENTATION
Everything in one place.
Setup guide, troubleshooting, aircraft notes, release information and direct support.
CONTACT DOCTORFO SUPPORT
Tell us what happened.
Complete the form below. DoctorFO will prepare a support email to support@doctorfo.com with the information we need to help you.
QUICK ANSWERS
Before you write, these may solve it.
DoctorFO does not connect to the PMDG 737-800. What should I check?
Confirm the PMDG SDK and CDU broadcast settings in 737_Options.ini, restart MSFS 2024, fully load the PMDG 737-800, then start DoctorFO and wait for PMDG CONNECTED.
Do I need OpenAI to use DoctorFO?
No. DoctorFO Core works without OpenAI. Your own OpenAI API key with API billing is required only for Melisa voice commands and natural conversation.
Why does FMC AUTO stay OFF?
FMC AUTO intentionally starts OFF on every DoctorFO launch. Confirm PMDG CONNECTED and SIMBRIEF READY, then enable AUTO when you want DoctorFO to run the tested FMC setup.
Is the 24-hour Trial the same as the paid version?
No. The public 24-hour Trial is Core-only. The Full license includes SimBrief/flight context, FMC AUTO and optional Melisa AI Voice with your own OpenAI API key.