For 73 years, the taxiway at Grider Field has had a leftward bend, what the Federal Aviation Administration calls a "non-standard deviation," that is getting straightened out with the help of federal and state money.
According to Pine Bluff Municipal Airport Manager Doug Hale, the taxiway at Grider Field was built parallel to the runway for most of its 5,998-foot length, but about two-thirds down the length of if from the north end, it deviates slightly to the left.
"It's been that way since the runway was constructed in 1947," Hale said. "Then, when the runway was extended back in the 1970s, the deviation continued. I have historic photographs of the airfield and there was nothing then or now that caused the deviation so I don't know why they did that."
One possible explanation came from Alex Smith, senior associate/project manager with McClelland Consulting Engineers.
"What I have heard is that back when they were building all of the training bases for the war, a lot of the taxiways were the same width as the runways so sometimes they would put a deviation at the end of the taxiway so the student pilots could tell the difference," Smith said.
"I've never heard that before," Hale said, "but that's the only explanation I've ever heard that makes any sense whatsoever. This is not the only airport I've ever seen from historical photos that has that deviation so that makes sense."
Neither man could confirm the explanation, however, especially considering that the runway was constructed well after World War II came to an end, and nearly three years after the airfield was decommissioned as an Army Air Corps training facility.
Hale pointed out four round-topped hangars that he said date from 1941, when Grider Field was constructed for the purpose of training pilots for the Army Air Corps.
"This was all open sod," he said, gesturing toward the runway. "Back then there was no runway. They vectored into the wind and that was their runway for the day. They would line the planes up outside the hangars and take off across the open field into the wind."
The taxiway project, which is being overseen by McClelland Consulting Engineers, is expected to take about six months to complete, weather permitting, Hale said. Currently, construction crews are in the process of relocating the electrical utilities that power a number of runway functions including the Visual Approach Slope Indicator (VASI) lights and the localizer antennas (LOC), which are the visual and instrument landing aids.
"The electrical utilities have to be moved first and everything reconnected so that the VASI and the localizer antenna don't have to be down for a long time," Hale said. He said once the utilities are moved, the task of rewiring and reconnecting the VASI and LOC systems should take less than a day.
Among other utilities, Hale pointed out, a transformer about 125 feet to the right of the south end of the taxiway will have to be moved.
"That darned near bull's-eyes the center line of where we're going," he said. "That's the first thing they'll have to move."
Smith explained that the VASI light system helps pilots orient their aircraft properly to be able to land at the proper glide path and altitude as they cross the threshold of the runway.
"You're supposed to cross the threshold of the runway at a certain elevation and be on a glide path of 3 degrees," Smith said. "The lights are angled with the middle light at 3 degrees and the ones on either side at 15 minutes up or down."
The LOC transmits a narrow radio frequency beam that pilots, using an instrument landing approach, can lock onto in order to bring the aircraft down at the proper altitude and glide path.
All of this work, Hale said, is being done at a cost of $1.9 million, $1.7 million of which is being paid for through the Federal Aeronautics Administration Airport Improvement Grants program, and $200,000 of which will eventually come from the Arkansas Department of Commerce-Division of Aeronautics.
"We'll get the 10% from the Division of Aeronautics, but the city gets to carry the note during the duration of the construction project," Hale explained.
During the construction, almost one third of the length of the 5,998-foot taxiway, which mirrors the length of the runway, will be closed, which means pilots taking off from the south end of the runway will have to exit the taxiway and go onto the runway to execute a maneuver known as "back-taxiing" to take off.
"When the wind is out of the north, the pilots will come and announce they are at the threshold," Hale said. "Then they'll back taxi to the end of the runway, turn around, do a 180, aim back out and then depart."
"The purpose of the taxiway is to prevent back taxiing," Smith said. "If you're taxiing down the runway and another plane is trying to land or take off, then there's a possible runway incursion. The taxiways prevent that."
A runway incursion is defined by the Federal Aeronautics Administration as, "Any occurrence at an aerodrome involving the incorrect presence of an aircraft, vehicle or person on the protected area of a surface designated for the landing and takeoff of aircraft." The FAA says on average, three runway incursions occur each day at airports across the country. The last fatal accident caused by a runway incursion, the FAA said, happened in 2006 at Blue Grass Airport in Lexington, Ky.
The reason it is important for runways and the accompanying taxiway to be perfectly parallel, Hale said, is one of safety. He explained that the center-line of the 150-foot wide runway and the 75-foot wide taxiway are supposed to be 500 feet apart, which, he said, for two-thirds of the length, they are. That distance allows for a safety zone that extends out from either center line to run parallel without converging.
"But," he said, "at the south end of the taxiway, those safety zones converge in what the FAA calls a non-standard deviation. It's not that it's completely unsafe; it's just a non-standard deviation in the airfield. It's supposed to be perfectly parallel."