When the first satellite weather receiver was installed in my Baron several years ago the local FAA inspectors insisted that the radio shop put a placard near the display commanding that "Satellite Weather Information Not To Be Used For IFR Navigation" before they would approve the system. I thought that was about the stupidest placard I had seen in an airplane. That early system delivered by low, Earth-orbiting satellites was not reliable enough to use for weather information, much less navigation. Plus, how do you navigate using weather information sent by satellite anyway?
Well, maybe that FAA inspector was prescient. Not long ago I did use the Nexrad radar image sent to my airplane by XM Weather to navigate my way back home to New York from Wichita. At least I used the XM information to know where not to go, which may be the opposite of navigation, which, I think, is knowing where you are, where you want to go and how to get there.
I had been in Wichita the week after Thanksgiving to fly the 500th King Air 350. The weather was weird even by Wichita standards with the wind blowing 30 knots plus from the south-that's not abnormal for Wichita-but the temperature was in the 70s, not normal for the end of November. All the forecasters were watching an extreme cold front marching down from the northwest and promised a big change for the next day.
Change it did with temperatures dropping into the mid 20s, low clouds, a forecast of several inches of snow and wind howling at 30 knots plus from the north. The front had passed. The problem for me and my plans to fly east was that the front was generating a near solid line of strong to severe thunderstorms stretching from north Texas to Chicago. The national Nexrad picture didn't show any gaps or even soft spots in the line that I would want to try to fly through. To add interest it was starting to precipitate some sort of drizzle that would soon be freezing. My flight plan was on file for a fuel stop in Columbus, Ohio, my normal route home, and I had to either get going or get frozen in at Wichita. The Wichita controller who gave me the clearance said he had very recent reports of tops at 4,100 feet-just 2,800 feet agl over Wichita-clear above, and only a trace of light ice in the clouds.
So, I had five hours and 20 minutes of fuel, a reliable report of good conditions aloft, several airports with conditions above ILS minimums, and a current display of the severe weather and current surface conditions that I could count on XM to update every five minutes. I decided to take off and see where the weather allowed me to go. The reports were accurate and I was quickly in clear air on top, having found only a trace of ice in the clouds. The line of thunderstorms was 80 to 100 miles to the east, and the wind aloft was screaming at 50 to 60 knots from the southwest at 7,000 feet. I asked Kansas City Center if I could fly northeast to Ottumwa, Iowa, before turning east toward Columbus. That looked like the first place the line of storms on the XM map of Nexrad radars would allow a turn to the east.
I was in perfectly smooth air, clear of clouds and enjoying a huge tailwind, secure in the knowledge XM provided that no severe weather lurked ahead of my nose, though the picture off the right wing tip was nothing but a solid line. The tailwind was also blowing the cells northeast so it became clear Ottumwa wasn't going to be far enough north to miss the weather. The next target became Dubuque.
Every five minutes a new radar picture came in, and the storms were building as well as moving toward the northeast. Dubuque would no longer work, but Madison, Wisconsin, looked okay. The Madison approach controller was great and let me pick my way through some broken buildups that were starting to pop and then turn east toward Muskegon, Michigan. My new plan, and clearance, was to land at Muskegon for fuel. But, again, the XM picture changed that. Cells were moving up Lake Michigan fast, and they would be over Muskegon before I could get gas and depart. The new plan was Flint, Michigan, well to the east of the cold front where it was 60º F, with drizzle so light that it didn't show on the Nexrad picture. A VOR approach into Flint, top the tanks, and I had an uneventful second leg home to New York with absolutely nothing to look at ahead on the Nexrad.
When I got home I plugged the route I flew into the flight planner and found the total distance home via Madison and Flint was 1,238 nm, versus 1,123 nm over the normal route stopping in Columbus. Because of the strong tailwinds on the first leg, total trip time was actually a little less than typical. It's amazing how little distance a seemingly big dogleg route adds to a long trip, particularly when you consider a more or less direct route was impossible, or at least unwise.
I would never have attempted the flight before XM because the available en route reports of the thunderstorms just aren't precise enough to make avoidance decisions. The other option is to turn the nose toward the storms and look at them with my onboard radar, but that provides only a small picture laterally, and the ship's radar cannot penetrate all the way through a wide line of storms to show you that it's clear all the way through.
