פורסם עם: General Aviation
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HANGING ALTITUDE
Sometimes your careful planning for a cross-country flight needs adjustment soon after you start. A common en route change is selecting a different cruise altitude. Once you decide that your altitude isn't satisfactory, act promptly. Sometimes a simple switch solves all problems. But remember never to confuse the need to change altitudes with a need to turn back or divert for safety.
If you decide that it is reasonable to continue, you will need a new altitude for your cruise leg. What's better: Up or down? If a haze layer is restricting visibility, it may be possible to climb above it. Likewise, turbulence on a fair day may be escaped by climbing above the altitude where thermals cease, as indicated by the tops of fair-weather cumulus clouds.
Climbing also can improve spotty radio communications. If you are navigating by VOR, its line-of-sight signal may improve with a climb. Perhaps you requested radar flight following from ATC and were advised that coverage is unavailable at your altitude; that's an excellent reason to climb. See the article "VFR traffic advisories" on AOPA Flight Training Online to learn how to determine in advance the altitudes where radar service is most likely to be provided.
Sometimes descending is the best plan. Winds aloft lower may be from a more advantageous direction, and typically—but not always—a lower velocity. See how much information can be extracted from a winds aloft forecast in the Nov. 3, 2006, Training Tip.
If an overcast is lower than forecast for your route, descending will let you maintain required clearance from clouds. If you noticed during your climb to cruise altitude that turbulence began, for example, above 5,000 feet msl, going back down may smooth the ride.
Whether climbing or descending, stay vigilant for opposing traffic, especially on published airways. Above 3,000 feet agl, observe the "hemispherical rule" for altitude selection, as discussed in the Feb. 7, 2003, Training Tip.
Keep track of increased fuel consumption if you climb! And file a pilot report to share the conditions you encountered with your fellow pilots. To learn how to file a pilot report, take the AOPA Air Safety Foundation's SkySpotter: Pireps Made Easy online course.