Originally Posted by
readywhenyouare
Oh good, someone who knows what they are talking about. Explain to me why some airlines ordered huge fleets of both A319 and A320 aircraft. From what I understand the operating costs of both the 319 and 320 are so similar that it is foolish to not use the A320 for its great capacity. To my understanding an aircraft like the A319 is only needed in limited numbers where its performance is needed.
PMDL had the textbook version of this with the 737-800 and 737-700. The -800 was ordered in the greatest number due to its great capacity. The -700 was ordered in limited numbers for airports where its performance was necessary. So why did NWA, UA, and US order so many A319's? This question has been bugging me for the longest time and no one has been able to answer to it.
Easy to answer: exchangeability. The A318/19/20/21 family as well as the B737-4/5/6/7/8/9 series models were disigned to complement each other, not to compete. From the begining on it was clear that the larger network carriers will always operate more then one version of these familys at the same time. As these planes can be exchanged vitually 10 minutes before boarding ( the A321 pilots need an additional 20 hour training on these longer birds apart from that they can fly each of them ) airlines switching them like they operational need them. If you know that your flight from a>b has 101 pax and the return flight has 122 pax why fly an A320 when an smaller, lighter A319 can do the job cheaper? For this reason alone large single aircraft operator like Southwest & Ryanair ( both 100% Boeing fleets ) will always have differenttypes of them in the fleet. Same reason why AF got all 4 A320 types in their fleet.
As for better high & hot performance on the A319: i don't think that plays a major role in the US. The only airlines that i'm aware off operating the A319 with A321 thrust parameters are operating in China (Nepal ) on the very high altitude airports there.