Incident Overview
On 25 July 2018, a DA20 C aircraft was being prepared for training flights at EP Modlin (EPMO). After refueling, the aircraft was turned 180 degrees and positioned for towing to the parking apron using a tug. The tug driver approached the aircraft, and the instructor attached the aircraft to the tug. After confirming readiness for towing, the student pilot occupied the aircraft. The instructor instructed the student to release the parking brake with the command "parking brake off" and then boarded the tug.
Towing and Discovery
With clearance from the airport duty officer, towing commenced toward apron number 12. After approximately 150 meters, the instructor heard a characteristic squeal from the braking system and observed smoke emanating from the landing gear of the towed aircraft. The tug driver immediately halted towing. The instructor retrieved a fire extinguisher, but extinguishing was not required. The parking brake was subsequently released, and after receiving clearance from the duty officer, the aircraft was towed to the hangar.
Post-Towing Actions
The instructor recorded in the aircraft technical log: "towing of aircraft with parking brake engaged." Technical personnel inspected the aircraft, replaced the brake pads, checked and lubricated the wheel bearings, and tested the braking system on the ground before releasing the aircraft for flight operations.
Probable Cause
The cause of the incident was a misinterpretation of the command issued to the student pilot before towing commenced, resulting in towing with the parking brake engaged.
Preventive Measures
The operator conducted a discussion with the student pilot about the event and recommended the use of visual signals (open and closed fist) between the tug driver and the person in the aircraft, in accordance with AIP VFR GEN 3.3, prior to starting the towing process. The investigation commission did not issue any safety recommendations.