That’s Two at Memphis

From today’s AP story about yesterday’s outage at Memphis Center:

"Any system that run 24/7, occasionally there's going to be an outage," she said. "Outages are very, very rare and we're very adept at handling them."

I assume Ms. Kathleen Bergen, even though she is only an FAA spokesperson, knows the difference between “rare” and too often. It’s like me, being only an ex-controller, can tell you that a car crash is not supposed to be able to cause a plane crash.

”The outage began about 3:30 p.m. CDT when a car in Memphis struck a utility pole and severed a fiber-optic cable, FAA spokeswoman Kathleen Bergen said, adding air safety was not compromised. “

Let me tell you what little I know about the power system at Atlanta Center -- where I used to work. Anyone that knows me well will laugh at the thought of me describing a mechanical system. I’m the dumbest of the dumb when it comes to anything mechanical. But the concept is really easy to understand. Even if you’re an FAA spokesperson.

At Atlanta Center (which is very much like Memphis Center), we had commercial power coming into the facility from two different sources. One line came in from a source to the north and a completely different electrical line came in from the south. Two independent sources of commercial power. Then we had two completely separate diesel generators. Either one could run what was called “critical power.” That was the supply needed to run the radar scopes and the radios. But that still wasn’t good enough. To back that up, we had an entire building full of batteries.

That’s a safe backup plan. Two sources of power, two backup generators and a battery backup. If the FAA went to that much trouble to backup just the power, what kind of system do you think they should have in place for the radios and radars ? If we’re not going to have an effective backup to the radios and radars you might as well do away with the expensive power system. The power is useless without the equipment it operates.

”Saturday's outage showed that the system needs more backups, said Ron Carpenter, a Memphis controller and president of the local branch of the National Air Traffic Controllers Association.

"The biggest concern that we have is that we are no longer talking to airplanes," Carpenter said. "We can do without radar (in an emergency), but we need to talk to airplanes." “

That statement should make it plain enough. The radar information and the radios should be on separate circuits. Each sector had three radios when I was a controller and I assume most still do. You had the main, the BUEC (BackUp Emergency Communication) and the BUEC could switch to a completely different radio site. In other words, if a car crashed into your radio transmitter -- taking out the whole site -- you could switch the radio to another site in another location.

The logic is the same. If we went to that much trouble to make sure our equipment was dependable, why would you have a “single point of failure” somewhere else in the system ? The answer is obvious. You wouldn’t.

I’ll wait to hear from the experts. In the meantime, I’ll remind you of what they told us last time.

”And Memphis Center was the site of perhaps the worst FTI-related outage, on Sept. 25, 2007. That day, a major failure left controllers without the ability to use most of their radio frequencies and some of their radar feeds. “

Don Brown
August 10, 2008