If a passenger airline can’t get aircraft delivered on time and has to meet its schedule, and there’s nothing in the market that is available, it’s off to the graveyard to look for equipment. How is that going?
The market is struggling to get the single-aisle aircraft it needs. In the chart, we can see that since 2011 there has been a steady stream of aircraft coming out of storage. And note these aircraft are not young.  But when you need the lift, what else can you do? Fortunately, during the period fuel costs were dropping. We can see the rise in fuel prices is having an effect though by 1Q18 as the blue line has bottomed out. Airbus and Boeing have good reason to seek higher rates.
Next twin aisles. There was a strong move to bring retired aircraft back in 2003 but that bottomed out by 2007. Since then there has been some variance, but the trend looks slightly like rising numbers of aircraft being parked. The average age of the parked fleet has been relatively stable since 2009.
Twin aisles have not seen the same market demand as single aisles. Moreover, it appears the trend of parking more aircraft and the age staying relatively stable may indicate many of the older twin aisles are being scrapped.