A master plan: Ennis Big Sky Airport plans for future

It is no surprise that use of the Ennis Big Sky Airport is on the rise, and has been in recent years. In fact, the growth rate has been around 30 percent per year for the last few years, according to Lance Bowser, engineer with Robert Peccia & Associates, the firm that handles engineering and construction on Madison County’s airports.

“That compounds very fast,” Bowser said. “It will taper off at some point, but when?”

Bowser led a presentation about the Ennis Big Sky Airport’s in-progress master plan at a public meeting on April 10. The airport’s master plan is being updated to correlate with an airport layout plan, to determine the type of facilities appropriate based on current and forecasted activity.

“We have to look at what we need to meet current facility requirements,” Boswer said. “And what is appropriate based on forecasted aircraft activity.”

Doing that requires defining the critical design aircraft in the short term, five years, the medium term, 10 years, and the long term, 20 years.

“Critical aircraft is used in determining design criteria for airport geometry based on the most demanding aircraft type with regular usage, which is defined as 500 operations,” Bowser said. “It’s forecasted to be a C-II-2 with a maximum take off weight of more than 12,500 pounds and less than 60,000 pounds.”

That information is what defines what is needed in future designs that may be incorporated into the Airport Layout Plan.

“After an airport starts to change, the master plan and airport layout plan become stale and no longer symmetrical to what is actually happening,” explained Tom Miller, Madison County Airport Board member. “Once the (Federal Aviation Administration) determined our traffic was significant enough to change us to a C-II classification, that changed everything on the airport from setbacks to placements.”


Facility needs

For example, the existing runway is 75 feet wide, but in the future, Bowser said it needs to be 100 feet wide to safely accommodate the type of aircraft using the airport.

From runway length, airspace, pavement strength, taxiway size, apron areas, fencing, snow removal equipment and more, the Ennis Big Sky Airport must undergo multiple upgrades to meet future need, though that is not to say the updates must happen immediately.

“This can be developed into a capital improvement plan,” Bowser said. “We can look at feasible construction over 20 years. It would be too restrictive money-wise to do it in one year.”

Another consideration is terminal area – for example, there may be demand for more rental car space at the airport in the future.

“We’ve already seen 110 rental cars in one month,” Bowser said.



There are a few alternatives to meet the facility requirements. The first, do nothing.

“Technically, that’s not an alternative,” Bowser said.

If an airport exceeds its substantial use threshold, the FAA will not fund improvements, meaning if the Madison County Airport Board and commissioners choose to not make improvements and the airport is unable to meet the needs of the critical design aircraft, the FAA will not provide money for updates. According to Bowser, “Airports are designed around specific standards associated with the determined critical aircraft using and forecasted to use the airport.” Improvements that do not meet those safety standards are not FAA eligible for assistance.

One alternative is to consider other sites.

“No other sites (around Ennis) are reasonable,” Bowser said. “It would be too expensive … we want to improve the current facility.”

The final two alternatives involve shifting or extending the existing runway to the north, the most feasible option.


Where to next

From here, developing a finalized airport layout plan is the next step. Once the plan is developed, it needs to be implemented.

The airport layout plan is a set of drawings that show the short, intermediate and long term facilities and associated airspace surfaces for the airport.

“The ALP is one of the main planning tools utilized to help anticipate future improvements at the airport are able to meet the needs of the community and safely accommodate its users,” Bowser explained. “Then we must track the tends and usage to determine if the usage is remaining consistent with forecasts and meeting the needs of the airport and its users.”

Or as Miller said, “if we build it, they will come.”

“In order to be ready for the future, we have to act now,” he said. “Doing all these things to modernize the airport and keep it on the cutting edge have led to huge demographic benefits in our community now and in the future.”



Any comments or questions should be directed to Lance Bowser, at lance@rpa-hln.com

Comments will be accepted through the end of April.

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