Night-time noisy flight mystery solved ?

So many complaints about individual flights that wake people in the darkest hours !  All very mysterious & unfathomable (according to Sea-Tac Airport and the FAA).  Now, RCAA research provides a partial answer.

Working with flight-operations data for Sea-Tac for the period 15 March - 5 April 2010, provided by the Airport's Noise Office, we have learnt that there is a consistent pattern of one particular carrier flying very noisy planes in & out of Sea-Tac.  That carrier is FedEx, flying  MD11s and DC10s -- the noisiest planes still in common (civilian) use. 

Shouldn't the Airport take some effective action to get these noisy birds out of the skies during the wee hours?  If not, why not?