Formosa Airlines Flight 7623

Formosa Airlines Flight 7623 was a scheduled domestic flight from Hsinchu to Kaohsiung, Taiwan. On 18 March 1998, the Saab 340 operating the flight crashed into the ocean shortly after takeoff in a severe right bank, killing all 13 occupants on-board. The investigation determined that the failure of a crucial electrical system, combined with flying in total darkness and a low cloud ceiling, led to the loss of control of the aircraft.

Flight

During pre-flight checks, the crew noticed a failure of the right-hand main bus, which resulted in the failure of more than 10 aircraft systems, including the right side of the Electronic Flight Instrument System (EFIS) in the cockpit, something which First Officer Hung pointed out. Captain Fei exclaimed that he had experienced the same failure in the same aircraft the day before. Even after bringing in the plane's mechanic, Wu Kai-ying, they couldn't fix the problem.

To determine whether the aircraft was safe to fly, the crew used the abnormal checklist to detect unsafe conditions, but they did not complete the entire checklist and were therefore unaware of the number of inoperative systems on-board. Captain Fei decided to continue the flight to get the plane to an airport where it could be repaired, but his statements on the Cockpit Voice Recorder (CVR) following taxi clearance revealed that he was uncomfortable with this decision.

After engine start, the right-hand anti-ice start bleed valve was in the default open position as a failsafe due to the failure of the right-hand main bus. As a result, the Internal Turbine Temperature (ITT) of engine No. 2 was 15°C higher than normal. That is, there was a difference of more than 30°C between the two engines.

Accident

Ten seconds after First Officer Hung responded to ATC, Captain Fei exclaimed that he had a problem with the heading and asked for help with the magnetic compass. Observer Cheu replied, "Um," but neither he nor the co-pilot made any significant response, probably because they were either in a state of confusion or unable to act. The plane rolled slowly to the right at a rate of one degree per second. 13 seconds later, the captain said, "Ask for radar vector," the plane was 2.3 degrees nose down and rolling 36 degrees to the right. At that moment, he made a brief aileron input to the right, exacerbating the roll.

Captain Fei made a quick exclamation, shouting, "Everything is wrong!" The aircraft was pitching down at 8.4 degrees with a bank angle of 47.5 degrees. ATC noticed the plane's deviation to the right and asked, "Bravo 12255, say heading now?" but no one answered. The situation in the cockpit was chaotic, the aircraft was pitching down even more and rolling at an angle of 71 degrees to the right, First Officer Hung responded to the captain by asking, "Sir, shall we look at this one?". The observer then spoke up and shouted, "Attitude!" Two seconds later, ATC again asked the flight to confirm their heading, at which point the overspeed warning went off at an airspeed of 245 knots.

Observer Cheu yelled again, "Sir, attitude!" and Captain Fei replied, "OK." At that point, the plane disappeared from the ATC radar. The engines accelerated as the plane rapidly approached the Taiwan Strait. "Ah!" the captain screamed while the first officer tried to make a quick transmission of "Bra-" but was unable to finish his sentence. At 19:32, rolling inverted with a right bank angle of 161 degrees and a pitch of 65 degrees nose down, the Saab 340 slammed into the water, instantly shattering the airplane. A fisherman heard what sounded like a massive explosion but couldn't see anything. None of the 13 people on board survived.<ref name="baaa" <ref name="ASN"