China Airlines Flight 611 was a regularly scheduled passenger flight from Taiwan to Hong Kong International Airport. At about 3:30pm on the 25th of May 2002, the Boeing 747-209B operating the route disintegrated in mid-air and crashed into the Taiwan Strait, 43 km northeast of the Penghu Islands, 20 minutes after takeoff, killing all 225 people on-board.
Investigations found the in-flight break-up was caused by metal fatigue cracks resulting from improper repairs to the aircraft 22 years earlier. As of 2022, the crash remains the deadliest in Taiwanese history, as well as the most recent accident of a 747 involving passenger fatalities.
Taiwan’s military radar provided a clear picture of the Boeing 747-200 breaking into four pieces about 20 minutes after take-off from Taipei on Saturday afternoon.
“There was an inflight break-up above the altitude of 30,000 feet. We are very positive about this,” said Kay Yong, head of Taiwan’s aviation safety council at the time.
The B-18255 was actually going to be sold to Orient Thai Airlines and this was the plane’s last day of service with China Airlines. Post flight investigations found that no distress signals were sent out. However, two Cathay Pacific planes nearby received flight 611’s location-indicator signals. Later, the investigators discovered that flight 611 broke apart in mid-air as it was reaching 35,000 feet.
Takeoff was at 3.07 pm, and the plane was cleared to climb to 20,000 feet. At 3.16 pm the plane was again cleared to climb and maintain 35,000 feet. At about 3.30 pm, the plane was about to reach 35,000 feet when it suddenly disappeared from the radar systems of the air traffic controllers Communications were also lost.
The pilots had a normal conversation with the control tower at Taipei airport until a last routine message at 3.16pm. At 3.29pm the plane disappeared off the control tower’s radar screen.
China Airlines has had nine fatal crashes between 1970 and 2002, with this crash being the worst record in commercial aviation.
The final investigation report found that the accident was the result of “metal fatigue” due to inadequate maintenance after a previous incident. The report found that on February 7, 1980, the accident aircraft suffered a tail strike occurrence in Hong Kong. The aircraft was then ferried back to Taiwan on the same day un-pressurized and a temporary repair was conducted the day after.
A permanent repair was conducted on May 23 through 26, 1980. However, the permanent repair of the tail strike was not accomplished in accordance with the Boeing SRM (Structure Repair Manual), in that the area of damaged skin in Section 46 was not removed and the repair doubler did not extend sufficiently beyond the entire damaged area to restore the structural strength.
Consequently, after repeating cycles of depressurization and pressurization during flights, the weakened hull started to crack gradually and finally broke open in flight on that flight, exactly 22 years after the faulty repair has been applied to the damaged tail. An explosive depressurization of the aircraft occurred once the crack was broken, causing the complete disintegration of the aircraft mid-air.