Capability
Air Data Instruments
The instruments that tell the crew how high and how fast — repaired at component level and verified against calibrated references.
Overview
What we see, and what we do.
Air data faults are unforgiving because everything downstream inherits them. A drifting encoder does not announce itself as an encoder problem; it shows up as an altitude reporting discrepancy that gets blamed on the transponder, and two serviceable units come off the aircraft before anyone looks at the right one.
We work these as a system. The instrument is repaired and calibrated across its operating range, not spot-checked at one altitude, and the results go back documented so the next person to see a discrepancy has a baseline to compare against.
Equipment We Service
- Encoding Altimeter
- Pneumatic Altimeter
- Airspeed Indicator
- Machmeter
- Vertical Speed Indicator
- Instantaneous VSI
- Blind Encoder
- Air Data Computer
- Altitude Alerter
- Static Inverter
Faults We See Most
- Altitude reporting discrepancy against ATC
- Altimeter drift or sticking needle
- Airspeed reading low or high across the range
- VSI failing to return to zero
- Encoder output disagreeing with the altimeter
- Leak in the static system
Recognise one of these? Describe what was observed rather than what you think has failed — it is frequently a different unit.
Common Questions
Air Data Instruments,
asked in practice.
- ATC reports an altitude discrepancy. Is it the transponder or the encoder?
- It can be either, and it is often neither — a leak in the static system produces the same symptom. This is why the three are worth testing together rather than in sequence. Replacing the transponder first is the most common and most expensive way to not fix it.
- Does an altimeter need checking across its whole range?
- Yes. An instrument that is accurate at one altitude and drifting at another is more dangerous than one that is obviously wrong, because the crew has no reason to distrust it. We calibrate across the operating range and the results go back documented.
- The fault only appears in the climb. Can you reproduce that on a bench?
- Usually. Altitude-dependent and rate-dependent faults are testable under controlled pressure change, which is exactly the condition that will not occur while the unit sits on a bench at room pressure.
Next Step
Air Data Instruments on the bench?
Send us the part number.
Tell us the aircraft, the symptom and the number on the dataplate. We will confirm whether we service it and what the options are.