ConcordeBoy is right, Las Vegas is an extemely difficult market......there is no problem with filing up flights, the problem is yeilds. Las Vegas is a very leisure oriented destination, and the yeilds are quite low, so it is very difficult for airlines to make a profit on routes to Las Vegas.
National was founded with the backing of several large casino operators in order to increase service in and out of LAS
.....the megahotels in Las Vegas were concerned that there was not enough air traffic and seats in and out of LAS
and that many of the large US airlines had cut back service into LAS
due to the low yeilds. The fact that Southwest has a large operation in/out of LAS
also does not help yeilds.....thus National was born with a hub at LAS
as Las Vegas' hometown airline.
National closed down mainly because some of its backers did not want to make further investments in funding the airline which was losing money. Flights were filled but at rather low fares. National operated with only one fleet type, the 757, which made sense on routes to New York and Chicago but was a lot of aircraft to fly on routes from LAS
- rumor had it that National was looking to add a smaller type to its fleet, but time ran out. And, the events of 9/11 certainly did not help National, as air traffic and fares dropped drastically after that terrible day.