What happened
Eastern Air Lines Flight 23 departed Los Angeles International Airport (LAX) with a total of 221 people on board, comprising three flight crew members, eight flight attendants, and 210 passengers. The aircraft was operating in semi-automatic mode for its pressurization system during the initial climbout phase. During this ascent, the second officer observed that the manual outflow valve control wheel failed to move toward the one-half closed position as expected.
In response to the anomaly, the second officer attempted to switch to the standby pressurization system before moving to full manual control. He noted that the manual control wheel was difficult to turn. Using the manual controls, the aircraft reached its cruise altitude. The standby system was then engaged again, which successfully maintained the cabin altitude.
The situation deteriorated during the descent into Miami (MIA). The outflow valve control wheel moved rapidly toward the open position. The second officer attempted to close the valve using the manual system but found that the wheel would not move at all, leaving the outflow valve fully open. Consequently, the crew donned oxygen masks and executed an emergency descent to 10,000 feet at a rate of 5,500 feet per minute.
The aircraft landed with the outflow valve remaining in the fully open position. The decompression event resulted in one flight attendant suffering a ruptured eardrum. Additionally, smoke appeared in the cabin due to the activation of one oxygen generator canister.