Tuesday, July 14, 2009
Lowest To Highest
From below sea level to a Colorado high in a light jet
At an elevation of 9,927 feet, Leadville is a little more challenging to fly into. The weather isn’t perfect, and it looks like we’ll have to fly an approach through some juicy-looking buildups with forecasted icing. The GPS approach to runway 16 starts at 14,000 feet with a minimum decent altitude of 1,432 feet above the runway. Fortunately, the weather is reported to be above minimums, so a landing seems likely. As the aircraft descends, sure enough, moderate rime ice starts to build on the way to the initial approach fix. Fortunately, the NEXRAD weather display shows that we’ll be turning away from the major returns when we make a 90-degree turn to start the approach. On the approach and about three miles from the airport, the ice is gone and we break out to the sight of runway 16 on the nose. The winds favor runway 34, so we fight moderate turbulence to circle to land. At 50 feet, the sensation of speed is hard to ignore, and the plane touches down with a satisfying chirp.
The flight into Leadville involved moderate rime icing in the clouds. Fortunately, NEXRAD showed that we would be turning toward better conditions on the GPS approach.
There are two kinds of instrument procedures that may affect our departure. The standard instrument departure (SID) typically requires a standard rate of climb of at least 200 feet per nm, unless otherwise noted. To accept an SID, the pilot must ensure that the airplane can maintain the required climb gradient—that’s almost never a problem with both engines running. It’s a good idea to check that the climb gradient can also be maintained on one engine. Note, however, that the loss of an engine would be an emergency so it’d be possible to deviate from the procedure should that happen.
The second kind of departure is an obstacle clearance departure (OCD), which is what we have out of Leadville. The OCD provides the route and climb gradient needed to safely clear terrain. ATC normally won’t assign the OCD out of uncontrolled airports like Leadville, but it’d be foolhardy to depart IFR in the clouds or at night and not follow the OCD. This is more than the legal requirement of an SID—you simply don’t want to depart into weather, lose an engine and not be able to stay out of the rocks. Leadville has an OCD for each runway direction, with different climb gradients, so a careful review of each procedure is required before departure.
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