01-00978-00 – Garmin GTP 59 Outside Air Temperature (OAT) Probe Kit
Available now through the AirParts Aero marketplace.
Overview Section
The Garmin GTP 59 (011-00978-00) is a high-accuracy Outside Air Temperature (OAT) probe designed for integration with Garmin’s G3X, G5, G3000, and G1000 glass cockpit systems. This precision sensor provides the raw thermal data required by the Air Data Computer (ADC) to calculate critical flight parameters, including True Airspeed (TAS), Density Altitude, and Wind Vectors.1
Constructed with a rugged stainless steel housing, the GTP 59 is a Resistance Temperature Detector (RTD).2 It is designed to be mounted externally on the fuselage or under the wing, where it can be exposed to high-velocity airflow while remaining isolated from the aircraft's internal heat signatures.3 The kit includes the probe, mounting hardware, and the specialized connector required for a clean avionics installation.
Key Features Section
High-Precision RTD Sensor: Utilizes advanced platinum resistance technology to provide temperature readings with minimal drift over thousands of flight hours.
Aerodynamic Shielding: The probe shape is optimized to minimize "self-heating" caused by skin friction (recovery factor), ensuring accurate readings at high cruise speeds.
Seamless Garmin Integration: Specifically designed to interface with the GSU 25 ADHARS or GDC 74/72 Air Data Computers via a simple three-wire interface.
All-Weather Durability: Encapsulated in a corrosion-resistant stainless steel body that withstands extreme thermal cycling, moisture, and high-altitude UV exposure.
Compact Footprint: Requires only a small 3/8-inch hole for installation, making it suitable for both pressurized and non-pressurized airframes.
Complete Installation Kit: The 011-00978-00 P/N includes the specialized nuts, washers, and terminal pins required for a certified installation.
Technical Specifications Section
| Specification | Detail |
| Part Number | 011-00978-00 |
| Manufacturer | Garmin International |
| Sensor Type | Platinum RTD (Resistance Temperature Detector) |
| Interface | 3-Wire (Power, Signal, Return) |
| Operating Temperature | -55°C to +70°C |
| Accuracy | +/- 1.5°C across the full operating range |
| Weight | 0.10 lbs (1.6 oz) |
| TSO Compliance | TSO-C106 (Air Data Computer Systems) |
Aircraft Compatibility Section
The GTP 59 is the standard OAT solution for nearly all Garmin-equipped aircraft in the AirParts Aero inventory:
Certified Aircraft: Standard equipment for Cessna 172/182/206 Nav III (G1000) and Beechcraft Bonanza/Baron G500/G600 retrofits.
Experimental / LSA: The primary OAT sensor for Garmin G3X Touch systems found in RV-series, CubCrafters, and Glasair aircraft.
Business Jets: Utilized as a standby or primary sensor in Citation and King Air platforms equipped with Garmin G1000 NXi or G3000 suites.
Technical Applications & Safety
The GTP 59 is essential for Performance-Based Navigation. Without accurate OAT data, the Air Data Computer cannot correctly calculate the local speed of sound. This would result in significant errors in True Airspeed (TAS) readings and incorrect wind speed/direction calculations.
Safety Warning: Proper placement is critical. The GTP 59 must be mounted away from engine exhaust, cowl flaps, or cabin heater vents. Even a 2-degree error caused by proximity to a heat source can result in a 4-knot error in True Airspeed at high altitudes, potentially affecting fuel planning and ETE (Estimated Time Enroute) calculations.
Technical Engineering Insight
The engineering excellence of the Garmin GTP 59 lies in its Linearity and Recovery Factor Compensation. Unlike inexpensive thermistors, the platinum RTD inside the GTP 59 provides a nearly linear resistance change relative to temperature. This allows the Garmin Air Data Computer to utilize a simpler, more robust algorithm for temperature conversion, reducing the computational overhead and increasing the reliability of the "Real-Time" data stream.
Furthermore, the GTP 59 is designed with a specific thermal mass that filters out momentary temperature spikes (such as flying through a small pocket of warm air), providing the pilot with a stable, "damped" reading. When installed through AirParts Aero, you are ensuring that your avionics suite receives the "clean" data required for RVSM accuracy and precise IFR navigation.
Installation & Maintenance Addendum
Wire Shielding: Always use shielded three-conductor wire as specified in the Garmin Installation Manual to prevent EMI from strobe lights or radio transmissions from inducing temperature "jitter."
Mounting Orientation: For best results, mount the probe in a location with "undisturbed" airflow, typically on the underside of the wing or the lower fuselage.
Calibration: While the GTP 59 is factory-calibrated, technicians can enter a temperature offset in the Garmin "Configuration Mode" to fine-tune the reading against a known-accurate reference thermometer.