RAT: The turbine powering the pod—and saving the aircraft
Civil aviation certification is extremely rigorous regarding flight safety.
This is no different for an aircraft's electrical generation and distribution systems.
The FAA and EASA classify engine generators as active sources, the Auxiliary Power Unit (APU) as an active backup, and the Ram Air Turbine (RAT) as a passive backup.
The APU is a small gas turbine that operates independently of the aircraft's main engines.
The RAT, on the other hand, is a completely independent small wind turbine powered by the airflow generated by the aircraft's forward motion.
APUs and RATs are typically found on large aircraft.
For instance, the ATR72-600 has neither an APU nor a RAT.
Batteries are present on every aircraft.
Why is a RAT system needed?
So, why is a RAT necessary?
No single power source offers sufficient redundancy on its own.
Battery power is not limitless.
The APU can also fail or become unavailable.
A recent example occurred on March 4, 2026, when the RAT deployed on an American Airlines Airbus A321 following the loss of both generators.
Conversely, in military applications, this same technology may be utilized for purposes entirely different from—and for reasons far more demanding than—those in the civil sector.
When developing an AEW&C (Airborne Early Warning & Control) aircraft from a Boeing 737, a P-72 Maritime Patrol Aircraft from an ATR72-600, or an Airborne SOJ (Stand-Off Jammer) from a Bombardier Global 6000, the aircraft's existing electrical architecture may prove insufficient to meet the demands of high-power mission systems.
The first step taken is to upgrade the active power source—essentially installing a larger generator.
What if that isn't enough?
As seen with our Airborne SOJ aircraft, the emergency APU system is transformed into a continuous power source. Alternatively, one might even consider a dedicated generator for the mission system.
But the most interesting aspect is the use of a RAT.
RAT = Independence!
The AN/ALQ-99 is a US tactical electronic warfare system developed in the late 1960s for the EA-6B Prowler.
Later, advanced versions were used on the EA-18G Growler.
And all of them featured RAT generators.
Israel’s ELTA Scorpius-EJ also utilizes a RAT.
In short, they all generate their own electricity.
The US maintains this approach with the AN/ALQ-249 Next Generation Jammer (NGJ) program.
So, why?
Aircraft have fixed capacities.
Modifying them comes at a cost.
And it creates platform dependency.
For instance, the RAT provided 27 kW for the ALQ-99; for the NGJ, that figure is 140 kW!
However, the RAT is no miracle solution.
It doesn't provide free electricity; it increases drag and fuel consumption.
RAT performance fluctuates with changes in speed, altitude, and air density.
Icing is another issue.
It is a mechanical system, meaning it requires maintenance!
But the advantage is clear: Independence.
In 2025, a project titled "Development of a RAT-Based In-Pod Electric Power Supply" was conducted with the support of Gazi University and TUSAŞ.
The target was 50 kW.
The outcome?
Making pods as independent as possible from the aircraft could pave the way for more modular systems with reduced platform dependency.
Ultimately, how you generate power is just as important as the amount of power the pod delivers!
I believe our work will prove beneficial.
Sivil havacılık sertifikasyonu, uçuş emniyeti açısından son derece katıdır.
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