What happened
On June 5, 2024, an EMBRAER ERJ190, operating as a commercial passenger flight, was performing an approach to runway 31R at Marseille–Provence airport. During the final stages of the approach, the crew determined the aircraft was not stabilized and initiated a go-around. Simultaneously, a microlight aircraft, registration 84OM, was conducting a cross-country flight through the Provence CTR.
As the EMBRAER ERJ190 climbed, its flight path intersected with the path of the microlight. The proximity was close enough to trigger a TCAS TA followed by a TCAS RA, instructing the crew to maintain vertical speed. The minimum separation between the two aircraft was recorded at 389 meters horizontally and 775 feet vertically.
The investigation
The investigation examined radio communications, flight data from the EMBRAER ERJ190's QAR, and the microlight's Garmin G3X computer. Investigators focused on a sequence of communication errors involving the Marseille–Provence Tower and Approach controllers.
It was established that a frequency change instruction intended for a departing aircraft was mistakenly read back by the pilot of 84OM. The Tower controller did not detect this error and confirmed the read-back. The microlight pilot, believing he had received authorization to transit the airspace, switched to the Provence Approach frequency. However, due to the microlight's low altitude and position, it was outside the coverage area of the northern sector's transceiver, rendering the pilot unable to hear the Approach controller or be heard by them.
Findings
- A read-back error occurred when the microlight pilot misinterpreted an instruction intended for another aircraft as a clearance for himself.
- The Tower controller's failure to repeat the call sign during the confirmation of the read-back contributed to the pilot's misplaced confidence.
- Lack of radio coverage at low altitudes in the northern sector of the Provence TMA prevented the Approach controller from communicating with the microlight once the pilot had switched frequencies.
- The pilot of the microlight proceeded to cross the runway axis without the required explicit authorization, believing the frequency change instruction implied permission to continue his transit.