Vincent,
Don't forget Turkish AF F-16's operate from Sigonella as well, the Arrow flights sound quite different from the Phantom flights, so I'm still guessing TuAF F-16's.
UN154 was mentioned by Malta ATC as a Challenger last Sunday.
http://www.maltaspotting.com reports it as C-FXHC CRJ2.
Some for today (April 18th):
18.29 Legacy44 (MV-22 USMC), sq 5544, dest. Sigonella
18.43 Herky765 (C130J 37 AS)
19.01 CTM1410 (? FAF)
19.02 Sarab55 (M2000 QatarAF), to Athens 124.625
19.55 FAF7403, confirmed as 2 Rafales, sq 2427
20.06 Forte10 (RQ-4B US), sq 1473, dir. Sigonella
20.22 FNY5110, sq 3667, IFR to Sigonella
20.25 Jolly11, confirmed as 2x HH-60 (US), continue to the ship
21.24 CFC74 (CC-177 429 Sq), 21.47 to Athens 124.625
22.43 Viking03 (F-16 RNoAF?)
23.30 Exxon24 (KC-135R 351 ARS), with Weasel21 flt, 2x F-16 USAF, when of the boom Weasel21 dir. Aviano
23.34 Ribas65 (MQ-1 US), dir. Sigonella