To take early advantage of the 2016 window wherein the company can begin adding more 76-seaters (with a corresponding number of 50-seaters to be withdrawn), UA will need to place an order for a mainline 90-100 seater at some point in the next 12 months.

The 50-seaters are a rapidly-declining value proposition for the company, and UA is eager to unload them just as much as passengers are. The concern is balancing the needs for high-yield feed continuity to the hubs (which the 50-seaters deliver at unsustainable CASM), cost of capital to acquire a new small mainline jet, and the fact that the first-gen large RJs are nearing the end of their production life cycle and thus long-term value is diminished with more efficient variants coming on within a few years.

2016 puts UA in a bit of a pickle as the E190 (E2) model with geared turbofan engine technology isn't expected to make its EIS until 2018, and is likely to slip a bit. I suspect that would be the ideal airplane for UA's 'NSNB' (new small narrowbody) per the JCBA. UA may take a hybrid approach and at some point this year or early next place an order for existing E190s for 2016 delivery to be flown by mainline crews, coupled with an E190E2 order for 2018/2019 delivery. This is similar to the 752 replacement program, which is presently dependent on the current 737-900ER, an airplane which is not exactly a 757 facsimile from a performance standpoint, and leaves UA with a gap in its fleet plan based on current network structure. The 737 MAX9 will close that gap slightly but isn't expected to enter service until at least 2017.

What I anticipate UA doing is maxing out its 70/76-seaters under the JCBA as soon as is practicable and ramping down as many 50-seaters as possible simply by taking that capacity out of the system. In time, a NSNB will be added to the mainline fleet, but I feel 2016 is a bit ambitious.