Originally Posted by Flyby1206

CAL/UAL by far dominate the NYC region. They control just over 70% of the passenger traffic through EWR. When you take the total traffic numbers for the entire NYC region (EWR/LGA/JFK/SWF) the totals look like this:

(2011 data)
CAL/UAL 25.8%
DL 19.2%
AA 13.5%
JB 12.9%
US 5.7%

Next year DL will gain a few points from the LGA slot swap, putting them around 22% of total NYC traffic. You can add the numbers and see what would happen if DL/JB or AA/JB went through.

http://www.panynj.gov/airports/pdf-traffic/ATR2011.pdf (page 47)

Also some numbers for JFK/LGA passenger traffic

JFK
JB 23.9%
DL 23.9%
AA 17.2%

LGA
DL 29.6%
AA 20.8%
US 17.6%
JB 3.5%

Viewing NYC as a whole then DL+B6 would be 32% of total traffic, effectively eliminating AA+US to less than half the presence that the other major alliances have in the most important market in the USA. It would even put UAL drastically behind. I'm not saying AA+US wont be effective for capturing traffic in the NYC area, but they are putting all their eggs into the PHL basket. NYC will be destroyed for AA+US if/when DL+B6 happens.

My personal opinion is that there need to be three major competitiors (AA, UA, DL) in NYC with roughly equal shares of the market. AA cant afford to let DL take B6 away (nor do I think the DOT would allow that).