Tuesday, July 14, 2009
Lowest To Highest
From below sea level to a Colorado high in a light jet
Lowest To Highest
I spent over a year making the transition from piloting a TBM 700 turboprop to becoming a jet pilot; a process that has taken me through an ATP rating, two type ratings, a lot of simulator time, a jet trip to Paris, a bit of mentoring, one or two scary moments, some frustration and piles of cash.
I started the process 17 years after soloing, with about 3,400 hours in my logbook and five years of turboprop experience. I’ve finally cleared the magic number of 100 hours of single-pilot jet time, but I’m not quite ready to be called a superhero. My story isn’t unusual for many GA pilots now flying the new generation of light jets. A few have even made the jump from single-engine, fixed-gear airplanes and managed the transition to qualify for single-pilot jet operations. It’s not easy, quick or cheap, but it’s possible.
This spring, I embarked on a trip in my Citation Mustang from the lowest airport in the continental United States (Furnace Creek in Death Valley, Calif., which is located 210 feet below sea level) to the highest (Lake County in Leadville, Colo., which is at an elevation of 9,927 feet). Such a trip is certainly possible in many piston airplanes (and would be easy in the TBM 700), but could it be done in a jet at a time of year when the temperatures are climbing into the triple digits? It would be a challenge for a newbie jet pilot like me, but I decided to give it a try to see what it takes to make it happen safely.
The 3,060-foot Furnace Creek runway is adjacent to the Furnace Creek Ranch and isn’t hard to spot from the air.
Operating a jet is different from operating a piston or turboprop airplane, and there’s a lot to learn in order to do it correctly. One of the first lessons is that virtually all operations are done IFR. Operating any jet below FL180 limits range, speed and economy—it just isn’t done. The second lesson is that nothing is improvised. One of the leading types of jet accidents involves running off the end of the runway on landing. Speeds must be carefully computed for each landing to take into account weight, temperature, aircraft configuration and runway requirements.
Keep in mind that jets are slippery and the engines can take seven to 10 seconds to spool up, so speed adjustments take time. The small throttle adjustments that a piston pilot might make to adjust speed have almost no immediate effect in a jet. It isn’t uncommon to pull the power to idle to get a jet to slow down; at the other extreme, full power can quickly get a jet out of an impending stall with little need to actually lower the nose. One other thing about jet power: Thrust is heavily dependent on altitude and temperature—unlike in turbocharged piston engines.
All of this makes sense if you understand that unlike early jets, modern high-bypass jet engines generate thrust by accelerating a large volume of air through a relatively small change in velocity. Modern engines produce the most thrust when the air is cold and dense. In warmer weather, thrust is noticeably decreased so that acceleration, climb rate and cruise speed go way down. This loss of thrust in hot weather is particularly noticeable for the small engines powering the new wave of light jets, since these airplanes aren’t as overpowered as many larger jets.
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