Poahi, the one advantage of old inefficient aircraft is that you can park them and forget them.
How many years has Northwest planned on parking the DC-9s? I'm sure it's been a while, just as United's been planning on parking the bulk of the 737s for several years. Airlines use them until it no longer makes financial sense. The good thing about this is when those planes are taken out of service, you have instant capacity cuts. Airlines with new aircraft and excess capacity either park planes (and those parked planes cost money in lease or debt payments) or sell them. I would expect the used aircraft market to be saturated very soon.
How many years has Northwest planned on parking the DC-9s? I'm sure it's been a while, just as United's been planning on parking the bulk of the 737s for several years. Airlines use them until it no longer makes financial sense. The good thing about this is when those planes are taken out of service, you have instant capacity cuts. Airlines with new aircraft and excess capacity either park planes (and those parked planes cost money in lease or debt payments) or sell them. I would expect the used aircraft market to be saturated very soon.