Originally Posted by tismfu
How had this hypothetical scenario of an airport closing and WN not moving to another area airport happened before? As fs2k2isfun said, DIA wasn't even on the drawing board when WN left.
I wonder how big WN's operation at Stapleton was in '86 and how it compared to WN's operation at DAL today. I'm also wondering how significant the delays were... from the sounds of it they appear to be much worse than DFW.
It was never very big. Service was to ABQ (6-7 flights a day) and PHX (3-4 flights a day). At best, it was a tenth the size of DAL's current 120 flights per day.
The problem with Stapleton's delays were two-fold:
1/ They occurred easily. The problem was that the two main runways (17R-35L and 17L-35R) were too close together for use in all conditions. In great weather, when everyone could see enough to shoot visual approaches, the place ran fine. When the cloud ceilings and/or visibilities declined such that visual approaches couldn't be conducted, that forced the use of ILS approaches, and that's where the problem arose. To be able to shoot parallel ILS approaches, you have to have a minimum of 2,500 feet between the two runway centerlines. To shoot simultaneous ILS approaches, the minimum centerline distance was 4,300 feet. Stapleton had about 1,500 feet of centerline separation, so that essentially closed one of the two runways, and just like when 3 lanes of a 6-lane freeway close, traffic backs up quickly, and delays ensue. The weather "trigger" for this happening was about a 2000 foot ceiling and 4 miles visibility (nowhere near 200-1/2 landing minimums), and 2000-4 is a common occurence at various times of the year.
2/ The above usually resulted in 2-3 hour ATC delays, and the effect on Southwest's operation was disproportionaly greater due to Southwest's small size at the time. During the 1983-1986 timeframe when Southwest was at Stapleton, they had maybe 60-70 aircraft, and these severely delayed flights would often make other flights late due to connections, etc.
To DFW's credit, the airport was built with these FAA 2,500 foot and 4,300 foot separation standards in mind, and those types of delays are not an issue here, nor are they, for that matter, at the
new Denver airport. The problem at Stapleton also existed at STL and SFO, and was a similar factor in Southwest's decision to pullout of SFO. In more recent years, the FAA has put in LDA and PRM approaches at STL and SFO, respectively, and while it's helped, the fundamental problem is still there.