Moving Up to a Jet

There are several types of jets that can be flown by a single pilot instead of a crew, and that holds additional appeal for the airplane owner who is freed from the complications and expense of having to take a copilot along. The Beechcraft Premier IA, the CitationJet series, the Mustang and the Embraer Phenom 100 are just some of the jets eligible for single-pilot operation. And more are in development.

So what's the big deal about jets? Why do the FAA, insurance companies and especially pilots view them as different creatures from propeller airplanes?

Some of the mystique is left over from the early jet age when our understanding of aerodynamics, particularly at high altitudes and high airspeeds, was not complete. Early jets did have many characteristics, such as the so-called "coffin corner," that could trap the inexperienced pilot. The "coffin corner" is largely a thing of the past, but in early jets the wing design was such that, at a high altitude and high weight, the jet could be flying just a few knots above the low-speed stall buffet, and just a few knots below the high-speed Mach buffet. In that situation, turbulence or the added load of aggressive maneuvering could put the airplane out of control.

Another reason a higher level of pilot training and experience has been demanded for jets is that they are certified to a higher standard of potential safety than propeller airplanes are. From takeoff to touchdown there is not a single failure, or even a series of aircraft or system failures, that is remotely possible that would prevent a jet from safely reaching a runway. But to make use of these redundant capabilities, the jet pilot has to perform to a high level and react correctly to each system failure or potential emergency. If the pilot isn't up to the task, the greater potential safety of the jet is squandered.

It is for this reason that the FAA requires the pilot of any jet to have a type rating in that airplane. A type rating, as the term implies, means that a pilot is rated to fly that specific type of jet. That differs from the requirement for propeller pilots to have a category rating, such as single-engine land, or multiengine land and so on. A type rating applies to a specific jet, such as a CE-525 (CitationJet), and, no matter how much experience you have in that type, it doesn't carry over to another type of jet.

But are jets really that different to fly? Does a pilot need different techniques than in a propeller airplane? Again, the answer is yes, but also no.

I think that most pilots new to jets are surprised, at least a little, by the time it takes the engines to spool up or down, and by the amount of power available.

The certification rules allow a jet engine to take as long as five seconds to accelerate from idle to maximum power. You may think five seconds is brief, but just try counting those seconds out as you wait for a full response to your power-lever movement. If you are already flying too slowly and need more power, a lot can happen in five seconds, and none of it will be good.

On your first few takeoffs in a jet, you will notice the lag in engine acceleration, and thus airplane acceleration, as you advance the throttles. But then you will also be surprised by the acceleration of the acceleration, if that makes sense. The power response from a jet engine is not normally linear. In other words, as the engine compressor and turbine start to spin faster and faster, the thrust is multiplying. So, if it takes four seconds for an engine to reach full power, more of that power will be produced in the last second or so than in the first three.

As you accelerate down the runway, the jet engine is feeding itself more air and thus increasing power output. This is called "ram recovery" because the slipstream air being rammed into the front of the engine is helping the compressor do its job. This phenomenon was even more noticeable in old straight turbojet engines that really got to work when the airspeed hit 200 knots or more, but it is still noticeable in modern turbofan engines in which the fan produces the big majority of thrust at low airspeeds and low altitudes.

At takeoff rotation, the jet has a huge excess of thrust because every takeoff is planned to be able to continue safely if one engine fails at the worst possible time on the runway. This excess thrust will amaze you at first because, unlike conventional propeller airplanes, the jet will both climb and accelerate with the nose up at a high angle. Pilots with only propeller airplane experience will be tempted to release back pressure on the yoke after rotation, but that will only allow the jet to blow through the 200-knot airport traffic area speed limit. In reality you will need to hold the rotation angle, maybe even increase it, and then reduce power a lot if you have an assigned level-off a few thousand feet above the airport.

Once up and flying, the jet is not all that different from propeller airplanes except that it requires more precision from the pilot. Because of the higher airspeeds and the wing design, very small changes in attitude will produce high vertical velocities. So, to capture and hold the assigned altitude with the necessary precision requires very accurate attitude control. The task is really compounded during turns in which — except at landing approach speed — it is necessary to bank steeply to produce a usable rate of turn. Thirty degrees is the maximum bank angle in a jet for all but unusual or emergency maneuvers, but at that angle it takes very precise nose-up pitch control, as well as bank angle control, to hold altitude.

I remember when I got my first Learjet type rating nearly 30 years ago. I had to complete all training tasks and the check ride in the airplane even though I had spent two weeks in FlightSafety's simulator and ground school course and had passed the ride in the sim. It was then the "Learjet way." But all during the training, and then for the check ride, I never was asked to wear a view-limiting hood as is normal in propeller airplane IFR training and checking. The examiner told me I was free to look out the windshield all I wanted, but he was going to be watching the instruments and there was nothing out the window that would help me stay on assigned altitude, airspeed and heading with the accuracy required. He was right. The view out the window might tell you up from down, but it sure won't help you stay right on the assigned altitude. Jet flying is 100 percent instrument flying.

Another flying-quality difference in many jets is lightly damped Dutch roll, particularly if the wing is swept. Dutch roll, of course, is caused by yaw when the advancing wing produces more lift than the retreating side and thus causes the airplane to roll toward the retreating wing. With a swept wing, this characteristic is amplified. Dutch roll can become a control issue when it is excited by turbulence, particularly at very high altitudes where the thinner air provides less natural damping. In the early days of jets, a number of pilots lost control because of undamped Dutch roll.

Many jets require the automatic yaw damper to be engaged all of the time, or at least above specified altitudes, to control Dutch roll. However, more recent aerodynamic features such as the inverted-V ventral fins found on many jets aerodynamically damp Dutch roll, making the electronic yaw damper more of a passenger comfort aid than an airplane control necessity.

Flying at very high altitudes — 41,000 feet always seems to be the level mentioned — is often cited as the reason jet pilots need to be more experienced, but why? The reason is that the air is extremely thin, and low air density can disrupt the behavior of the wing and engines. At very high altitudes, the wing is experiencing the effects of Mach, which can cause shock waves to build on the wing or tail. These waves can disrupt lift production and cause unexpected pitching if the proper airspeed is not maintained or the wing is too highly loaded by an altitude too high for the airplane's weight, by steep turns or by turbulence.

More recently designed jets have wings that are very forgiving at high altitude and high speed compared with those of jets from one or two generations ago. That means the modern jet can tolerate sloppier flying without biting the pilot, but still there are limits, and at very high altitude in any jet the pilot needs to be smooth and remain well within the operating limitations.

Jet engines also feel the effects of the thin air at altitude, and the compressors can stall if maneuvers are too abrupt or if turbulence is encountered. Again, the margins in newer engines are much better than they were years ago. Any reasonably good control of the airplane will work, but high altitude simply increases the emphasis on the need for good flying skills. Of course, the autopilot will do the flying at high altitude, and it is typically required to be engaged when flying level above FL 290 in reduced vertical separation minimum standard (RVSM) airspace, but the human is the backup for the autopilot and must be ready to assume control at any moment.

The new jet pilot will really need to be at the top of his game for maneuvering in the terminal area and for the approach and landing. More jet accidents happen on approach and landing than during any other phase of flight.

The big difference in flying the approach in a jet is again the slower engine-throttle response than that in a propeller airplane. This is particularly important when the jet is configured to land. Jets have higher wing loadings than propeller airplanes, a condition that cuts drag in cruise flight but also increases stalling speed and thus increases approach speed, which in turn requires longer runways. To help reduce the stall speed despite the smaller wing area, nearly all jets have larger and more effective flaps than a propeller airplane does, and we all know that flaps add drag as well as lift.

Because a jet will have more drag than most propeller airplanes when configured for landing, you must be careful not to allow airspeed to decay. It is crucial that the jet pilot monitor airspeed trends and move the throttles aggressively to keep the airplane from decelerating below target approach speed. This job is, again, made more difficult by the slower response from the engine. The pilot needs to anticipate the need for more, or less, power and stay ahead of the airspeed trends.

The big fear on approach is that the airplane, with its high drag flaps, will start sinking, and the inexperienced pilot will add power too late to arrest the descent. That can and has happened, and the results are usually disastrous.

However, the more common accident for jet pilots, particularly those short on experience, results from approaching too fast, landing too long and running off the end of the runway. The only thing worse is the pilot who realizes he can't stop in time and tries a late go-around and runs off the end accelerating, but not flying, instead of slowing. That is a certain recipe for tragedy.

The solution for either hitting short or landing long is the same — accurate airspeed control. Modern flat-glass avionics with the airspeed trend indicator have made airspeed control much easier. The indicator is a little tape that moves up and down on the airspeed scale to show where the airspeed will be in a specified number of seconds if the current acceleration or deceleration continues. The trend indicator gives you five or 10 seconds of warning for adjusting the power to return to the target speed.

What pilots new to jets will find unusual about landing is the site picture near the runway. All but a handful of jets approach the runway in a level to slightly nose-up attitude, while nearly all propeller airplanes approach at least a little nose-down. Because the jet's nose is already close to the landing attitude, any additional back pressure on the wheel will halt the descent prematurely. It's very easy for the new jet pilot to flare too high and sit there with airspeed bleeding off rapidly and the runway too many feet below.

Many jets have radio altimeters that audibly count down the last 50 feet, and that can be a big help in knowing that you are still descending, because the visual cues can be misleading. But there is nothing like experience in each type of jet to know what the landing attitude looks like, where to start to flare, how much to flare and how to get the airplane down to the runway without floating over long distances.

Transitioning into a jet is something that any competent propeller pilot can do with the proper training. But if you think there is a jet in your future, the best way to get ready is to fly your propeller airplane with the greatest precision you can demand of yourself. If you get used to nailing every altitude, heading and course in whatever you fly now, you'll be ready for the jet. Pilots of propeller airplanes simply get more slack from the authorities, and the airplane, than pilots of a jet, but there is no reason you can't fly any airplane with everything right on the center.