Adiru
🧭 1️⃣ What ADIRU Means
ADIRU = Air Data Inertial Reference Unit
It combines two systems into one box:
| Part | Full Name | Function |
|---|---|---|
| ADI | Air Data part | Measures air pressures & temperature (airspeed, altitude, Mach) |
| IRU | Inertial Reference part | Measures motion (attitude, heading, acceleration, position) |
So basically —
✈️ The ADIRU tells the aircraft “how fast, how high, and which way it’s moving.”
⚙️ 2️⃣ What Goes Into It
The ADIRU receives inputs from sensors:
| Input Source | Measurement | Used By |
|---|---|---|
| Pitot Tubes | Total Pressure | Airspeed |
| Static Ports | Static Pressure | Altitude |
| TAT Probe | Temperature | TAS, Mach |
| AoA Probes | Angle of Attack | Stall protection, flight laws |
| Laser or Ring Laser Gyros | Rotation rate | Attitude & heading |
| Accelerometers | Linear acceleration | Speed and position |
| GPS or IRS Update | Position fix | Navigation correction |
🧮 3️⃣ What Comes Out of It
The ADIRU sends processed data to all major systems:
| Output Data | Used For |
|---|---|
| Airspeed, Altitude, Mach, TAS | PFD (Primary Flight Display) & Autothrust |
| Attitude (Pitch, Roll) | PFD & Autopilot |
| Heading / Track | Navigation & flight directors |
| Vertical Speed | PFD & autopilot |
| Position, Groundspeed | FMS, GPS updates |
| Angle of Attack | Stall warning, flight envelope protection |
So it feeds the entire flight guidance system (Autopilot, FMS, Flight Directors, Stall Warning, etc.).
🧩 4️⃣ Simple Block Concept
┌────────────────────────────┐
│ ADIRU │
│ ┌──────────────┐ ┌──────┐ │
│ │ Air Data (AD)│ │ Inertial│ │
│ │ Speed, Alt, │ │ Pitch, │ │
│ │ Mach, Temp │ │ Roll, Yaw│ │
│ └──────────────┘ └──────┘ │
└──────────┬───────────────┘
│
▼
FMS • Autopilot • PFD • Stall Warn
✈️ 5️⃣ Example — Airbus & Boeing
Airbus (A320/A350): 3 independent ADIRUs supply air data & attitude to 3 Air Data Reference (ADR) and 3 Inertial Reference (IR) channels. If one fails, others continue — redundancy for safety.
Boeing (737/787): Similar setup — 2 or 3 ADIRUs feeding the EFIS, FMC, and autopilot systems.
🧠 6️⃣ In Simple Words
The ADIRU is like the aircraft’s brain for air and motion — it knows how high, how fast, and which way you’re moving, and sends that information to every other system that needs it.