December 1, 2012
By Jim Moore
Seated in the back of a Beechcraft Super King Air 300 en route to the next navaid, facing a pair of flat-screen monitors that display the collective input of an impressive array of sensors and antennae, Tom Clements, a mission specialist of 35 years, insisted the job never gets old.
“Every day can be different,” said Clements, who has seen more instrument approaches than most, monitoring the electronic signals that guide aircraft to runways and recording every detail. His career has included trips to Antarctica, where FAA Flight Inspection Services crews test and validate microwave signals that guide military transport aircraft to the ice runways of McMurdo Station, and the South Pole itself.
FAA flight inspection has evolved in many ways in the two decades since this King Air got its first coat of blue-and-white paint. International missions run in conjunction with U.S. Air Force crews typically last three weeks, and have taken FAA crews to Iraq and Afghanistan, along with other foreign military bases.
The effort to build an airspace infrastructure in Iraq and Afghanistan has not been universally welcomed. In May 2010, an FAA flight inspection Challenger 601 landed in Balad, Iraq, for a fuel stop after testing instrument approaches over Baghdad. The maintenance crew found a bullet—possibly from an AK-47—had punched a hole clean through the vertical stabilizer, damaging a bundle of wires in the fuel-control system.
Ground fire is, thankfully, not routine for the inspection pilots and mission specialists who constantly crisscross the country testing instrument procedures and measuring signals from navaids with exquisite precision. Flight inspection crews may sometimes test the patience of harried air traffic controllers (they check the busiest airports in the wee hours), but the flight inspection aircraft are welcome more often than not.
The crews are, after all, testing systems that safeguard millions of passengers and pilots each day, around the clock, in all weather.
While the aircraft fleet is being upgraded for NextGen operations, the core of the mission has remained unchanged: electronic verification that the navaids are accurate, and visual verification that obstacles are clearly marked. Before each procedure is published, and on a recurring schedule thereafter, it must be proven to be flyable and correct, a task that falls to a select group of aviators who are the final link in a long chain of specialists who design a path to runways ranging from the busiest Class B to the sleepiest strips in the national airspace system.
“We go to every farmer’s field that’s got an approach,” said Clements, who began his flight inspection career seated backwards in the back of a Sabreliner, monitoring instruments that spat out data on thermal paper. Seated facing forward in the cabin of N79, among the first of 18 King Airs in the fleet to be gutted and refitted for NextGen operations, Clements works a Windows-based computer running software customized to calculate tolerances measured in fractions of a centimeter, or microamperes of signal. Much of the work of organizing and reporting the data used to be done by hand.
“We’ve evolved quite a bit since then,” Clements said, his finger gliding over a screen packed with numbers as he explained each in turn.
Time was loran held promise to serve small airfields where ground-based equipment was cost-prohibitive, but the advent of GPS has relegated loran to the history books. In February 2012, the FAA celebrated a milestone: publication of 3,000 approaches that use Wide Area Augmentation System satellite signals to support GPS approaches with minima that in some cases match the typical 200 feet of ILS.
On this particular flight, a demonstration for AOPA, the King Air is headed to Antlers, Oklahoma, where 3,298 feet of pavement and a slumbering airport await. The RNAV (GPS) Runway 35 approach to Antlers will guide future pilots to a decision altitude of 904 feet. First, an array of instruments packed in cabinets that line the right side of the King Air’s cabin must verify tight tolerances: course alignment within 0.1 degree, a glidepath within 0.09 degree of the 3-degree target, a threshold crossing height within 10 feet below or 12 feet above the design target of 40 feet. More than 100 different parameters can be measured simultaneously. A camera mounted in the tail will snap a photograph as the threshold is crossed.
As Clements records the data, the pilots are flying the procedure (by hand), occasionally banking to visually verify that obstacles are accurately depicted on an approach plate marked “prototype: not for navigation.”
“Flyability is a critical component of what we do,” Clements said.
The FAA and the Air Force continuously monitor the integrity of satellite GPS signals, although they are also measured by the flight inspection aircraft. Ground-based navaids are checked for performance—and exacting tolerances—by an array of more than a dozen different antennae packed into the twin turboprop; and Clements is also searching for interference from welding shops and other sources that can compete with critical signals. Each time Clements turns on the recording software, a database with more than 75 years of information painstakingly collected from the national airspace system grows a little larger.
The King Air bound for Antlers is based at Will Rogers World Airport in Oklahoma City, the hub of a worldwide flight inspection operation. (There are six regional offices scattered around the country to facilitate the operation.) In an air-conditioned control room packed with projection screens and computer stations, dispatchers begin the process of planning what are typically week-long missions, using software to find the most efficient way to work through a checklist of airports and navaids in need of attention. In cavernous hangars on the sprawling campus, a crew of 90 maintenance technicians handles routine repairs as well as major overhauls. Another 60 technicians are stationed at the field offices.
The flight inspection fleet includes 32 aircraft—18 turboprops and 12 jets, including six Learjets and six Challengers. The overall operation runs on a $60 million budget, with another $9 million for big-ticket upgrades (although Douglas Vaz, manager of flight inspection services, said only about half that amount is spent in a typical year, fluctuating based on need). Between this hub and regional offices located around the country, the staff numbers about 530 pilots, technicians, dispatchers, and specialists.
Nonprecision approaches are tested every 540 days, and precision approaches get checked every 270 days, each flagged for attention in turn by a computer system that helps dispatchers build individual missions. A patrol through an airspace crowded with airports can keep Clements and fellow mission specialists very busy.
If lightning strikes a localizer, or repairs are required for other reasons, it gets much more immediate attention—a flight test must be conducted before the navaid can return to service. “Our goal is a 48-hour response time, anywhere in the country,” Vaz said.
Fast response, accurate measurements, and accurate flying are points of pride among the flight inspection team. While there are a few private contractors in addition to the government crews that perform the same mission around the world, “We set the standard,” Clements said.
AOPA Online Associate Editor Jim Moore joined AOPA in 2011 and is an instrument-rated private pilot who enjoys competition aerobatics.
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