Delta Air Lines is now one the world’s largest airlines. It serves over 180m passengers per year, has 80,000 employees and serves 323 destinations. The following table lists the current fleet and what is on order. Note the age of some of these aircraft – Delta is well known for its appreciation of low cost second hand aircraft it can secure. 
It is clear that Delta has to start replacing some of its fleet. In November 2016 Delta announced it selected the A350-900 and A330-900 to replace Boeing 747 and 767s starting in 2017 and 2019, respectively. In April 2016 Delta announced its order for 75 firm CS100s and 50 options that can be converted to the CS300. Also in April 2016 Delta announced an agreement with Airbus to acquire 37 additional A321s as part of its efforts to renew its narrowbody fleet. Delta’s order for the 737-900ER was announced in August 2011 when the airline ordered 100. Delta referred to the 737-900ER order as replacing on a capacity-neutral basis (180-seat) older technology aircraft that will be retired from the fleet.
Delta has been retiring 757 and 767s slowly. These two aircraft have been the backbone of the fleet. The following chart illustrates how significant these models have been at Delta for some time. In passing, note these models also fall right in the MoM range.
If we look at the Delta fleet by seat count we get an idea of the company’s thinking so far on fleet renewal. Because there are several seat configurations for the 757 and 767, we averaged these to get a general idea on seat numbers.
It seems the CS100 could be replacing both the 737-700s and A319s. Clearly the ex-Northwest A319s are likely to be the first to be retired. If the CS100 is successful at Delta, the options are possibly going to be exercised and converted to CS300s. This is happening at SWISS.
At the near-200 seat segment, Delta seems to be hedging its bets with the 737-900ER and A321. Certainly these new aircraft can replace the 757s for domestic North America. But for Trans Atlantic the A321eo might be a better bet, but Delta has not selected this model (A321’s “acquired near the end of the model’s production cycle”). Ed Bastian, Delta’s CEO said “The order for the A321s is an opportunistic fleet move that enables us to produce strong returns and cost-effectively accelerate the retirement of Delta’s 116 MD-88s in a capital efficient manner.” But the seat count between these two aircraft is wide, making the statement appear odd. We would bet the A321neo is in play at Delta.
Delta claimed the A330-900 is going to replace 767s. But the 25 on order is way short to accomplish this. Delta said the A330-900 is going to replace the 767-300ER. It would seem there could be more A330neos coming to make this happen.
The A350 is to replace the 747-400s. But there about four times as many A350s on order as there are 747-400s. Might these A350s also eventually replace the 777LRs?
As we hope to have demonstrated, Delta’s fleet renewal is not fully executed. There are clearly more steps to come.
Delta has the oldest and worst fleet in the business. The planes are dirty and worse. I do not understand why the American flyer does not see the Delta flight for what it is – old and awful.