Complex sentence: The aircraft involved was a Boeing 767-300ER (registration number "N345AN"), delivered to American on the 16th of April, 2003, making it 13.5 years old at the time of the incident.
Split into simpler sentences: The aircraft involved was a Boeing 767-300ER (registration number "N345AN"). The Boeing 767 was delivered to American on April 16th, 2003, and was 13.5 years old at the time of the incident.