MARINE CORPS AIR STATION MIRAMAR, Calif. -- On dark, cloudy nights, when helicopter pilots have no visual reference point, they must rely and trust in the avionics instruments, like the altimeter, to get them safely to their destination.

Ensuring the instruments are in good working order are avionics Marines, like those with Marine Aviation Logistics Squadron 16, Marine Aircraft Group 16, 3rd Marine Aircraft Wing.

The Marines of the calibration lab, which is part of the squadron's avionics section, ensure the equipment used to test the avionics gear is in proper working order.

"We're the backbone of the squadron and the group, fixing everybody's problems," said Gunnery Sgt. Eric G. Garcia, staff noncommissioned officer-in-charge, calibration lab, avionics section, MALS-16. "We don't work on the avionics of the aircraft. We work on anything used to test the avionics, ensuring the testing gear operates within a given set of tolerances - making sure it does what it's supposed to do."

When the lab receives the test equipment from the different avionics sections, an inventory of the gear is performed before it is turned over to the work center where the actual calibration and repairs are done.

"The job can be very routine work, especially the record keeping," said Cpl. Salina E. Molina, calibration noncommissioned officer for issue and receiving with MALS-16. "We have to keep good records, making sure that if the equipment came in with 20 wires, that it goes out with 20 wires."

With all the equipment coming in and out of the calibration lab, a schedule must be used to ensure that all gear is calibrated on time.

"The calibration Marines are responsible for actually picking up the gear when it is due for calibration according to the equipment's schedule. Anything used for quantitative measurement must be checked to make sure it tests within a given tolerance," said Garcia. "For example; a digital multimeter. We make sure that if it reads one volt, it is really one volt, because if it doesn't read correctly then some of the systems like the Initiate Friend or Foe will not work properly and lead to a fratricide incident."

Along with playing the part of safety watchdog, the Marines within the calibration lab view themselves as gatekeepers to the group's level of readiness, according to Cpl. Julio C. Carcamo Jr., calibration technician with MALS-16.

"We are pretty much unknown outside of avionics, but we're the backbone of support for the logistics squadron. Everything comes through us," said Carcamo.

Along with the calibration of avionics test equipment, the Marines are responsible for procurement of replacement parts on the equipment they are constantly evaluating.

"After the lab's Marines tell us what's wrong - what part is broken on the test gear - we hit the Web to locate it," said Staff Sgt. Christopher M. Brusich, expeditor, calibration lab, MALS-16. "It's like trying to find parts for an old car - you have to be creative in your search to locate it.

"We spend hours on the Web checking different suppliers for the pieces, a difficult task made tougher by the fact that many of the parts aren't made any more. Sometimes it's better to buy a whole component than a small piece because it's cheaper," he added.

According to the section's enlisted leader, a certain type of person does well working in the calibration lab.

"If you love opening stuff up and seeing how it works, then you'll love this job," said Garcia.