High-transmission lines are not the typical electric line. These are the lines that power your local power company.

"The voltage we carry through the line, we're typically the bulk supplier to our local distributors who reduce it down," explained Tracy Flippo, TVA Vice President.

On the 10-year anniversary of a major blackout in the Northeast, the Tennessee Valley Authority took our cameras along for a bird's eye view of how they inspect the more than 16,000 miles.

It's a process they do twice a year.

As they are flying through, the lineman in the front of the helicopter uses a computer to mark any problems he sees; line crews are then able to come back and fix the problem. "He's looking for wires that may be frayed or wires that may be broken, what we call danger trees," says Flippo.

The crew pointed out the strict vegetation management program TVA uses to keep the lines free of overgrowth. "The philosophy is if we have it to the easement, then we are just maintaining the floor, which is much more efficient and much more cost-effective," says Flippo.

TVA officials say Mother Nature is the biggest threat to these lines. During the 2011 tornadoes, 50 large towers were knocked down from Alabama to Tennessee.

TVA officials say their goal is to reduce the number of outages they experience and to keep those that do happen to as short as possible.

The average TVA outage over the last three years is just 13 minutes.