Waypoints

AOPA Pilot Editor in Chief Thomas B. Haines has flown dozens of models of piston and turbine airplanes.

Many general aviation pilots spend a lifetime of flying without ever sampling that rarified flight-level air pumped into the pressurized cabin of a turboprop or business jet. For others, trips to the flight levels on turbine-powered wings are few and far between indeed. Such unfamiliarity causes some pilots to think that the ease of operation and dramatic performance capabilities of turbine airplanes relieve their pilots from doing much more than actuating the autopilot after takeoff. But you might be surprised to know that pilots of all types, whether the fuel they buy is blue or clear, face similar plights.

I've flown dozens of turbine airplanes over the years, but seldom for very long at a time. Every time I strap on a turbine airplane, it's almost as if it were a new experience for me. The times I've flown turbine airplanes over long distances and multiple legs, I have been amazed at the level of decision making that is necessary on an ongoing basis. Minute-by-minute planning isn't something faced only by piston pilots attempting to pick their way through weather and from fuel stop to fuel stop. Despite the greater capabilities of their airplanes, turbine pilots face similar issues.

A few years ago, I flew a TBM 700 single-engine turboprop from the Socata factory in the south of France to the company's U.S. headquarters near Miami. The 20 hours of flying over two days allowed me to get comfortable in the airplane. Aside from the final leg from Charleston, South Carolina, to Miami, we faced little serious weather during the entire trip. Fuel planning wasn't all that difficult because the choices are so limited across the North Atlantic. Before departing "across the pond" we fueled at Glasgow, Scotland. Next stop, Reykjavik, Iceland — whether you like it or not because there aren't many other options. Farther east, you'd better become familiar with the airports on Greenland and pick one of the few available. We chose Narsarsuaq. Goose Bay, Newfoundland, Canada, is next because you'll need fuel by then and it's the first place to get it. Next, clear U.S. Customs in Bangor, Maine. From there we were on our own to Miami. The trip from Bangor to Charleston was the longest of the journey. From Charleston south we faced a tremendous number of thunderstorms peppering all of Florida and areas off both coasts. No problem for a high-flying turboprop, right? Wrong. Even at FL280 the big storms towered over us, forcing deviations left and right of course. The airborne weather radar, Stormscope, deicing boots, and the trusty Pratt & Whitney's continuous growl helped, but I still felt like a Bonanza pilot as we weighed one course over the other.

Thunderstorms routinely top out above 40,000 feet. Few turboprops are certified for flight above 30,000 feet. The altitude and equipment certainly give turboprop pilots more options, but the mighty turbine is no vaccine against en route weather encounters.

Weather also plagued a more recent long turboprop flight, but the real challenge was the fuel planning. In this case it was a Mitsubishi MU-2 twin turboprop en route from Frederick, Maryland, to AOPA Expo in Palm Springs, California. The swift MU-2 can cruise at true airspeeds greater than 315 knots, but to get those speeds and to reduce fuel burns to less than bring-your-own-refinery rates you must fly high. Mother Nature, in apparent payback for your burning up all of those dead dinosaurs, can really turn up the wind velocities at those kinds of altitudes. So there we sat, truing 310 kt while America churned by below at the more sedate rate of 240 kt. Forty to 100 kt of headwinds taunted us all day long.

Even with the hurricane-force winds we believed we could make the trip with just one stop, in Tulsa, Oklahoma, where I had a meeting planned with Intercontinental Jets to learn about its program for converting the MU-2's Honeywell Garrett TPE331-5 or -6 engines to -10 engines. The conversion significantly increases performance and reduces maintenance and fuel burns. Tulsa is conveniently in the middle of the country where we would need a fuel stop.

At a leisurely headwind-induced pace, we headed west at FL240 and later FL260. With a couple of calculations we quickly discovered that we would arrive in Tulsa with enough fuel to be legal, but not much more, especially if the weather were low — and of course it was. Tulsa was reporting ceilings of 100 feet and one-quarter mile visibility. But the cloud-cover was forecast to lift by the time we got there. It did, but only marginally. By the time we were into the Midwest, conditions had jumped all the way to 300 and one — doable, but uncomfortably close on the fuel burns if we had to hold for any length of time. We declared Bingo on the fuel and diverted to Branson, Missouri. The 42-minute flight from Branson to Tulsa proved easy because by then the conditions had improved to VFR. I was less than an hour late for the appointment and still in time for lunch.

With full tanks and bellies we headed west hoping for some relief from the wind. We didn't get it for quite a while. Again, at FL260, the winds gnawed our groundspeed to the mid-200s. Using the Garmin GNS 430's trip-planning feature, we crafted various scenarios. If the wind backed off just a little we could make it to Palm Springs without an additional stop. But without some relief we'd be looking at another stop. Prescott, Arizona, was our backup. As Flagstaff passed under our right wing and Prescott crawled onto the top edge of the moving-map display we ran the numbers again and decided we could make Palm Springs. The winds were calming a bit, allowing the groundspeed to climb up to around 280 kt. We landed at dusk with adequate reserves. Every Midwest and East Coast pilot we talked to over the three days at AOPA Expo complained about the winds.

No matter how mighty the steed, it is never quite fast enough nor quite long-legged enough to suit every mission. Pilots not familiar with turbine airplanes sometimes think they can drone on for many hours without refueling. Truth be told, the endurance of most turboprops and light jets is about the same as most piston-powered airplanes. The difference, of course, is that turbine airplanes will fly many more miles during the same time period and burn much more fuel. The comfortable endurance of the MU-2, for example, is about 3.5 hours — about the same as my Beechcraft A36 Bonanza. The Bonanza will burn about 58 of its 74 usable gallons during that time while traveling about 580 nm in the illusive no-wind scenario. Tip tanks can add two more hours of endurance, greatly reducing the need for fuel stops.

During the climb, the MU-2's pair of Garrett engines will burn a total of nearly 100 gallons an hour. At high-speed cruise in the mid-20s, fuel burn drops to about 72 to 84 gph, depending on altitude and conditions. A total fuel capacity of 364 gallons for this model of MU-2 seems like a lot (especially when it's time to pay for a full tank), but it goes fast at those fuel flows. However, during the 3.5 hours between fill ups you'll traverse some 1,000 nm.

One advantage turbine pilots have over those flying light piston airplanes is an accurate fuel-measuring system. Turbine pilots can actually look at the gauges and know how much fuel they have. For the most part, piston pilots must either rely on a watch and knowledge of fuel burn at particular power settings or they can install an aftermarket fuel computer that makes cross-country planning much easier.

You might think that given the strong headwinds en route to Expo we'd enjoy a nice tailwind on the way home. We thought so too. But as we leveled off after departing Palm Springs, we saw groundspeeds of only about 280 kt — more than 20 kt of headwind! How can this be? Can life be this unfair?

After about 30 minutes, though, the winds kicked around to our tail and we saw the groundspeed begin to nudge up. Ultimately it zoomed to 380 kt — a 70-kt push. An approach to near minimums at Salina, Kansas, for fuel and cookies at Flower Aviation added to the day's adventure. The second leg proved uneventful as we skimmed through the tops of a few clouds over the Midwest as the sun set behind us. Crossing into the Ohio River Valley, we left the weather and clouds behind and flew into the starlit night with a continuing tailwind. We landed in Frederick 6.1 flight hours after leaving Palm Springs. Our door-to-door time was far less than those traversing the country on the airlines and our trip certainly more memorable.

E-mail the author at [email protected].