The route gave him every kind of topographic checkpoint he could hope to use, so pilotage would be easy. A number of military training routes (MTRs) crossed his route, but they were below 1,500 feet, and Dudley planned to fly at 7,500 feet. Of six VORs, two (ENL and CQO), near the beginning and end of his route, respectively, had HIWAS, which meant Dudley could get in-flight hazardous weather warnings.
When Dudley checked the weather on his laptop, using his newly-installed DTC DUATS Windows interface (Figure 1), it looked initially like he had picked a winner. Because he?d already set up his request lists, he got a standard briefing, flight log, special use airspace check, and several weather graphics in under two minutes.
An area of high pressure was centered just north of his route, and any convective activity looked to be nearly half a continent away (Figure 2). The Doppler chart and the severe weather potential chart (Figures 3 and 4) also showed nothing to concern him. But when he checked DTC?s 11Z ?flight rules? chart (Figure 5), which shows areas of VFR, Marginal VFR, and IFR conditions, it looked like bad news. Areas of IFR covered eastern Missouri and southern Illinois, right where he wanted to go.
Not quite undaunted, Dudley looked at the text output next. He saw that his long trip would take him through three forecast areas, Chicago (for Missouri, Illinois, and Kentucky); Dallas-Fort Worth (Tennessee), and Miami (Georgia). The Chicago forecast predicted mostly clear skies, but occasional visibility at three to five miles in mist through eastern Missouri and Illinois until 8 a.m. CDT (13Z), and until 9 a.m. CDT in western Kentucky, with scattered clouds at 4,000 feet until 11 a.m. Because it was now 7:45 a.m. CDT, he wasn?t too worried.
The DFW area forecast for the middle and western parts of Tennessee had the same local visibility in mist until 8 a.m. CDT, with scattered clouds at 5,000 feet after 10 a.m. The forecast for northwest Georgia also predicted three to five mile visibility in mist until 9 a.m. EDT, with scattered clouds at 4,000 to 5,000 feet after noon.
There were no SIGMETs, Convective SIGMETs, or Center Weather Advisories (CWAs). There was an AIRMET Sierra (for IFR) for a wide area that included most of Illinois, Indiana, and western Kentucky (almost the first half of his route) for occasional visibility below three miles in fog and mist, ending between 9 and 11 a.m. CDT. That got his attention. So much for his lucky day, Dudley thought. It looked like he?d encounter a widespread area of low visibility, and this bore looking into. At least there were no AIRMETs for turbulence or icing.
To get more information to support or refute the forecasts, Dudley read the current METARs for airports along his route. They reported little or no wind, occasional patchy fog or mist, and ? another crucial ingredient ? an area of small or nonexistent temperature/dewpoint spreads that covered the first half of his route. Dudley knew that when the temperature/dewpoint spread is close or non-existent, it didn?t take much for water vapor in the air to condense and cloud a pilot?s visibility.
Also, two airports, one in southern Illinois and the other in western Kentucky, issued special observations over a very few minutes to report rapidly lowering ceilings and visibility. As luck would have it, no METARs were available near his route for more than 200 miles, between Paducah, Kentucky, and Chattanooga, Tennessee. Past Chattanooga, however, ceilings and visibility improved, with no radar echoes.
Based on this information, if he had been at the airport right now, Dudley would have stayed on the ground. Although KSUS now had three miles visibility in mist with clear skies below 12,000 feet, Dudley would never fly over widespread areas of fog.
If he wouldn?t go now, what about later? Digging into the forecasts, by 9 a.m. (14Z) KSUS was predicted to have more than six miles visibility and clear skies. Belleville, Illinois, about 40 miles east, said about the same, but expected a few clouds at 3,500 feet. Paducah, about one third of the way to Atlanta, predicted more than six miles visibility and clear skies after 9 a.m. Chattanooga, about fourth-fifths of the way to Atlanta, predicted more than six miles visibility and scattered clouds at 4,500 feet after 11 a.m. EDT.
The weather looked pretty good for later, so Dudley decided to play the optimist (always okay to do when you?re still on the ground) and planned a 10 a.m. departure. Returning from breakfast just after 9 a.m., he downloaded another briefing and scanned the METARs. Dudley saw that things had indeed improved. All surface observations now indicated good VFR weather, and the temperature/dewpoint spreads were widening. It?s a go!
At 9:54, Dudley listened to ATIS at KSUS. The winds were calm, with 10 miles visibility, clear skies below 12,000 feet, temperature 14?C, dewpoint 11?C ? so far, the weather was as advertised. Dudley took off a few minutes past 10 a.m., and after an hour, it seemed clear that the air wasn?t so wringing wet, after all. He saw almost no clouds anywhere, except for a few isolated areas of scattered clouds at 4,000 or 5,000 feet.
Passing Paducah at 11:30 a.m., he listened to the ASOS frequency, which reported a light easterly wind, 10 miles visibility, and clear skies below 12,000 feet (and by his observation, ASOS was correct). That was right on with the 7:30 a.m. forecast. A few minutes later, knowing he was crossing a large area of relatively sparse forecast data, Dudley called Flight Watch. Happily, they reported nothing he needed to anticipate, other than checking his course, and enjoying the scenery.
At 1:17 p.m., about 13 miles northwest of Chattanooga, Dudley jumped an hour into the future, entering the Eastern Time Zone. The 2:20 p.m. EDT ATIS recording from Lovell Field reported variable wind at four knots, 10 miles visibility, sky clear below 12,000 and, he was pleased to see, temperature/dewpoints of 21?C/9?C. These, too, were better wind, visibility, and cloud cover than the earlier forecast.
By the time he got set up for landing at DeKalb-Peachtree, its ATIS recording gave almost the same report as he?d gotten from Chattanooga ? again a bit better than had been forecast...another fortuitous (but well-informed) journey?s end.