Narrative:At around 10:39 flight TG943, a Thai Airways Boeing 747-400 registered HS-TGY, requested clearance for a flight to Rome. It was a hot, sunny summer day and visibility was good. The crew had received a NOTAM indicating: "WIP ON PORTION OF TWY I-8 BETWEEN STAND T12 AND T13, MAX ACFT FOR TAXIING IS A321 , STANDS T12 AND TB CLOSED".
They received clearance for start up and were told to contact ground. There were some delays but at 11:20 the co-pilot of the 747, requested push back and start up. At 11:25 the aircraft was requested to taxi "VIA MIKE, HOLDING POINT THREE SIX RIGHT." However, by that time another aircraft (a Boeing B-767) requested push back at gate T-1, and therefore the ATCO asked the crew of the B747: " ... ARE YOU ABLE TO TAXI VIA CHARLlE FOUR AND THEN MIKE TO THE RIGHT?" at 11:26. The crew answered: "OK TAKE CHARLlE FOUR AND MIKE THAI NINE FOUR THREE" at 11:26. The ATCO confirmed.
There were no other communications between the B747 aircraft and the ATCO until 11:30:50, when the crew called ground ATC ("GROUND THAI NINE FOUR THREE"). The answer of the ATCO was: "THAI NINE FOUR THREE YOU WERE CLEARED TO TAXI VIA MIKE. THAT'S NOT MIKE, THAT'S INNER TAXIWAY AND I'M AFRAID IS NOT POSSIBLE TO TAXI, TO CONTINUE TAXIING ... STAND BY, PLEASE". The flight crew answered "WE HIT THE AIRCRAFT THAI NINE FOUR THREE" at 11:31:07.
As the 747 deviated from the normal taxiway centerline, following the new, modified centerline, the crew questioned their ability to clear a Régional Embraer EMB-135 aircraft, registered F-GOHC which was parked on stand 22 to the right of the taxiway in that zone. The copilot could see the right hand wing tip of the B747 from his seat on the right side of the cockpit. They were taxiing carefully at that time because the path was narrowing. The FDR data showed a groundspeed of 6-8 kt at that time. The copilot recalled saying they could possibly pass but with little clearance. He stated that at some point he said, "Stop!" and applied the brakes, but the aircraft was already very close to the EMB-135 and hit its T-tail, which completely detached and fell to the ground . The B747 suffered damage to its winglet.
CAUSE: "It is considered that the accident probably happened because, after the B747 aircraft inadvertently entered taxiway I-8, the flight crew did not adequately assess the lack of clearance of the right wing of their aircraft with the tail of an aircraft that was parked on the right side of that taxiway.
The air traffic control service could not advise the flight crew they had entered taxiway I-8 because the aircraft's progress was not monitored for more than a minute."
» Thai clarifies incident concerning flight TG 943 routed Madrid-Rome (Thai press release)
Official accident investigation report