 In February 2007 , Alaska Airlines introduced its first two Boeing 737 – 400 Combis to their fleet in order to replace their aging Boeing 737 – 200 Combi aircraft . The − 400 Combis have 20 % more passenger and cargo capacity than the aircraft they replaced , and can carry a combination of four cargo pallets and 72 passengers . The aircraft were originally introduced as passenger aircraft in 1992 , but have now been converted by Pemco Air Services . Pemco Air Services also converted the airline 's Boeing 737 @-@ 400F . 
