Contrails

Company King Air, 1000 Feet above Us

We're 124 Miles north of YXE at FL250, there's a company King Air trailing us by a bout 17 miles. They just called us on the company frequency to let us know that we are leaving contrails in the cold sky. I look at the OAT gauge it's showing -45 degrees Celsius, that's indicated. To get the true outside air temp I minus about 6 degrees to correct for ram air warming. As we fly through the air at 260 knots, the friction created on the temp prob by the passing air actually warms the prob up. The True OAT is -52, cold.

About 5 hours later, we're homeward bound on the last leg of our day. We're the ones trailing company now. They're about 22 miles ahead of us at FL220. We can't see them, but they're leaving behind bright white streaks in the blue sky. Cool, the plane I fly is big enough to leave contrails, it's a neat sight. Soon we hear another company KingAir coming towards us at FL240, we spot them and there are nice contrails behing them also. I'm able to get a good picture of this one. It's been a good day in the office.

It's Cold at 25'000 feet!