What happened
On October 31, 2017, an Embraint 175LR (ERJ-170-200LR) was operating a scheduled flight from Warsaw to Geneva, with a return leg planned to Warsaw. Shortly after takeoff, at approximately 500 ft, the crew received several EICAS (Engine Indicating and Crew Alerting System) messages indicating overpressure in both bleed air systems and the subsequent shutdown of bleed air 2. Due to existing maintenance configurations under the Minimum Equipment List (MEL), bleed air 1 was already inactive for the duration of the flight.
As the aircraft continued its climb through mountainous terrain, the cabin altitude began to rise rapidly. Upon reaching flight level 260, the cabin altitude had reached 9,000 ft, prompting the crew to initiate a descent. The cabin altitude peaked at approximately 12,000 ft while the aircraft was at flight level 160. Following a 'CABIN ALTITUDE HIGH' alert, the crew performed an emergency descent to flight level 100. During the event, the crew manually deployed oxygen masks, and one passenger reported chest pain.
The investigation
The investigation examined the technical failures and the crew's response to the EICAS messages. It was noted that the initial pressurization of the aircraft without functioning bleed air systems may have led to a misinterpretation of the technical failure by the crew. The investigation also reviewed the simulator training programs for the Embraer fleet, noting that the specific checklist for 'CABIN ALTITUDE HIGH' was not included in the existing simulator sessions.
Findings
- The primary cause of the incident was the improper interpretation of a technical malfunction, which resulted in the crew continuing the climb while both bleed air systems were inactive.
- The lack of active bleed air systems prevented effective aircraft pressurization.
- A lack of specific training in the simulator regarding the 'CABIN ALTITUDE HIGH' checklist contributed to the crew's handling of the situation.