What’s With All The Turbo…Drama?

It seems like once a week someone asks me a version of this question: “Most of my hours are turboprop time. Will that hurt my chances of getting hired by a major airline?”

This subject is a can of worms. I’m writing this in the hopes of simplifying all our lives. I want to open it once here, dig around a bit, seal it back up, and just send a link when I’m asked this question in the future.

(Disclaimer: I wish I knew exactly how each hiring department looks at this question, but I don’t. Your best bet is always to get as much valuable experience as you can and be a great pilot wherever you are.)

So, let’s start with nomenclature. This is the first place where we confuse ourselves and get into trouble. In some cases, it may be that your aviation knowledge is rusty or underdeveloped. (We’ll fix that now.) Most of the time when I screw this up though, it’s just because I’m being lazy. Let’s agree to fix that ourselves, okay? (You may not need this refresher. I’m not presenting it to insult your intelligence. Please bear with those of us who will benefit from the education.) There are five terms we need to straighten out:

• Turbo
• Turbine
• Turbojet
• Turboprop
• Turbofan

Turbo

If you’re talking professional/Part 121/airline aviation, you should probably stop using the term “Turbo” altogether. This term identifies a piston engine with a turbocharger. The turbocharger uses engine exhaust to spin a small, single-stage turbine. This turbine is mechanically connected to a separate turbine that compresses intake air, allowing the engine to burn a richer mixture than would normally be allowed for a given temperature/altitude. It’s a cool technology that has done a lot for our world. If you want to read more about it, I recommend starting with the Wikipedia article.

There aren’t many airline jobs flying piston airplanes anymore, turbocharged or otherwise. (Though this one does look like fun. My seaplane CFI flew for them for a while and she seemed to love it!) If you own GA aircraft, you may find yourself using this term more. Otherwise, using “turbo” as an abbreviation to describe anything related to a turbine-based engine will only confuse you and cause you to make mistakes. I don’t love piston engines. Lots of moving parts, exhaust valves like to get sticky, limited power to weight ratio…it’s the same technology you have in your car and it’s been around for more than a century. The only way to make use of the energy output of this engine is to attach it to a propeller. Thankfully, there’s a better alternative!

Turbine

A turbine engine uses what are essentially a series of fans to compress air before injecting fuel and setting the mixture on fire. Usually the resulting exhaust gasses are spewed out the back of the engine, resulting in thrust (and plenty of glorious noise!) In most cases, we add an extra turbine or two near the exhaust end of this setup to capture some of the energy and use it to turn other things. (We’ll get to those variants in a moment.)

A turbine engine is great for many reasons. It has fewer moving parts than a piston engine, and since they’re generally all spinning in the same direction all the time they don’t wear as much. The reliability of turbine engines is by far better than that of pistons. Turbine engines compress the air, like a turbocharged piston but better, so they perform well in hot/high situations. Best of all, the technology scales up better than piston engines do. That’s why 777 engines, each producing more than 100,000 pounds of thrust and having a diameter as large as my 717’s fuselage (Uh, huh huh!), are turbine engines, rather than giant radial pistons like we saw on WWII bombers. Almost all of airline/military aviation abandoned pistons in favor of turbines years ago.

There are three types of turbine engines worth covering here. The first is:

The Turbojet

This is the original turbine engine. It’s old technology and actually not widely used all by itself today. (Even most fighters go for some type of turbofan, see below.) All of a turbojet’s thrust comes from the hot exhaust being expelled out the back of the motor. It was great when it was all we had available; however, it has some drawbacks. These motors consume a lot of fuel per pound of thrust, compared to newer alternatives. Older designs tend to have a long spool-up time when transitioning from low to high power settings. (Like on a go-around when you really need it…right…NOW!) They weren’t as reliable as modern turbine engines, but that may have just been because the technology was younger. They’re also very loud, which causes trouble for airports and operators. One of the better options is:

The Turboprop

This is a turbine engine. However, it doesn’t use much of the exhaust gas directly for thrust. Instead, it puts a power turbine or two in that exhaust stream. The exhaust spins this power turbine and that energy is used to spin a propeller, usually at the front of the engine. This propeller has advantages and disadvantages. It’s generally more fuel efficient than a straight turbojet engine. The propeller makes descending and stopping a lot easier. It’s also a quieter setup overall. Unfortunately, propellers lose efficiency quickly above the high 20s and they come with a bunch of expensive moving parts that can easily break. Propellers also tend to limit your top speed. Turboprops show up in commuter airlines and cargo operations that aren’t as worried about flying far or flying fast. They’re also great for backcountry flying in places like Alaska and Siberia. They’re powerful, reliable engines that do a lot of serious aviation. However, if you want speed, altitude, or range, your best bet right now is:

The Turbofan

Snobs don’t like to acknowledge this, but a turbofan is nothing more than a turboprop. A turbofan generally takes advantage of some of the direct thrust from exhaust gasses. However, it uses much of the exhaust to spin a power turbine, which spins a rotating collection of airfoils at the front of the engine. The only differences are that there tend to be more airfoil blades in this fan than most propellers, and that they’re shrouded or ducted…meaning that there is a ring of metal around the outside diameter of the fan. That ring seeks to eliminate the wingtip vortex/induced drag you get at the tip of a traditional propeller, increasing efficiency and giving other benefits.

Yes, a turbofan is probably less complex overall than a turboprop, and yes, it gets a lot more thrust directly from hot gasses than a turboprop. However, there’s a funny thing here. Originally, we added fans to turbojet engines and found them to be better in almost every way: quieter, more efficient, more reliable. Upon experimentation, we found that the thrust coming from the fan was more valuable than that coming from the tail pipe. Today, we usually fly with “high bypass ratio” turbofans. This means that our engines get at least 3-4 times as much airflow from this ducted propeller (aka fan) as they get from the hot gasses spewing from the tailpipe. The most efficient (and profitable) engines in the world go to much higher bypass ratios, and get much greater benefits.

Not only are high bypass ratio turbofans very efficient, they’re much quieter than straight turbojets. They’re the best we have for commercial aviation right now.

So, why is everyone so worked up about turbine time, and even worse, about turbofan vs turboprop time?

We’ve already established the fact that a turbofan is just a fancy turboprop on a fundamental, big-picture level. So, my first answer is that you have better things to worry about than whether the turbine hours in your logbook are associated with a shrouded or unshrouded propeller.

What’s most important is that you have Turbine time. In my opinion, airlines want this because there is a vast difference between most turbine flying and most piston flying. We all start out flying piston aircraft because they’re more affordable at the low-performance end of the spectrum. Unless you fly a warbird or an experimental kit aircraft, you’ll probably never fly piston airplane faster than about 200 knots, higher than about 18,000 feet, or longer than a few hours at a time. These airplanes tend to be relatively simple to operate, even with one pilot.

Turbine aircraft fly faster, higher, and further. You need to have a decision-making process adapted to those speeds. You need high-altitude physiology training. You need to be able to plan for and adapt to weather and atmospheric conditions that change at both the altitudes and distances you’re likely to cover on a given flight.

These aircraft are usually more complex and require greater systems knowledge to effectively operate. This level of knowledge is significantly beyond anything involved with most piston airplanes. They’re heavier aircraft, meaning they handle differently. This all usually results in needing a crew to fly them. Crew Resource Management (CRM) is a science and an art unto itself. It can trip up even experienced professional pilots, so operators want you have to as much experience at it as possible.

I’d say the different levels of care and effort required between piston and turbine flying are like middle school vs college. Our industry is used to helping pilots make this transition, but a manager hiring for a turbine job would always rather have a pilot with turbine experience.

While turboprops and turbofans are very similar mechanically, there are some important differences in how we operate them. I assert that the difference between turbofan and turboprop operations is about like grad school vs undergrad. However, for some people that’s a big leap.

Turboprops operate in the 20s, around 200-300 KIAS, and have relatively slow approach speeds. Unless you’re doing military flying, these aircraft generally gross-out at weights well under 100,000 pounds. A lot of their flying is measured in the hundreds, rather than multiple thousands of miles.

Turbofans, on the other hand, fly in the 30s or even 40s. They read Mach speeds, rather than indicated airspeed, at altitude. They regularly fly at ground speeds above 500 kts. They are much larger/heavier planes with associated higher approach speeds. All of these speed profiles mean that we pilots must adapt very quickly to changes. These aircraft are increasingly complex and can fly for thousands of miles. This introduces us to challenges in weather, CRM, and personal physiology that young pilots probably haven’t experienced before. Knowing this, put yourself in the shoes of a hiring manager. It’s suddenly easy to see why they’d rather have people with turbofan time.

So, what if you’ve only ever flown Saabs for Silver, Q400s for Horizon, or C-2s/P- 3s/C-130s/C- 12s/U-28s/T- 34s/T-6s for the military? Are you screwed?

I say no.

First and foremost: the airlines need pilots. A pilot with nothing but single-pilot piston time is not ready to fly big turbofans. However, an experienced turboprop pilot is more likely to have the chops to successfully make that leap. Deep down even the snobs realize that your turboprop time is valuable and they’ll take that into account. Even if your particular company is hesitant to take turboprop-only pilots now, they won’t have the luxury of being so choosy for long.

Next: my airline (and I suspect all of the others) are big-picture on pilot hiring. They want pilots with valuable training and experience…anyone can sit in a right seat and raise the gear for thousands of hours. The value of your flying and background can make a difference for you. I wrote a post about some of the “other” stuff you can do to make yourself more attractive (Getting your Airline App Noticed, Part 2).

Marc Himelhoch  from Cockpit2Cockpit LLC just started writing a series of articles on the same subject (Your Leadership Profile…How to Enhance Your Airline Application).