What happened
On August 7, 2023, a Red Sea Airlines charter flight, operating a Boeing 737-8Q8 with registration SU-RSB, was en route from Hurghada International Airport (HEGN) to Porto Airport (LPPR). While cruising at flight level 370 near Zamora, Spain, the crew received a master caution indication regarding a failure in the aircraft's pressurization control system.
As the aircraft's cabin altitude rose, the crew utilized oxygen masks. During the descent, the crew contacted Portuguese air traffic control at flight level 324. While passing through flight level 200, the crew declared a Mayday emergency, requesting a descent to flight level 100 due to the ongoing pressurization issues. The aircraft eventually landed at Porto at 22:48 local time.
Upon arrival, five passengers and two crew members were treated at the airport medical center for symptoms including ear and chest pain, anxiety, and fatigue. One crew member also experienced a nosebleed originating from the middle ear.
The investigation
The GPIAAF conducted an evaluation of the incident, reviewing air traffic control communications, medical reports, and the aircraft' and operator's technical logs. The investigation established that the cabin pressure controller (CPC#1) had failed. Maintenance records indicated that the controller was deactivated and the aircraft was subsequently dispatched under the Minimum Equipment List (MEL).
The investigation also noted that the operator did not report the event in accordance with required European legislation and international best practices. Furthermore, the GPIAAF could not verify certain details, such as the exact passenger count or the specific maintenance actions performed in Cairo, due to a lack of sufficient data from the operator.