Very light and personal jets (part 3)

In this part we conclude our introduction to the realm of VLJ/PLJ’s by considering operational aspects and costs associated with these aircraft as well as other factors to be considered by potential "jet jocks."

The biggest secret to flying jets well is to "be ahead of the aircraft," or so the RCAF taught us. This is true for many reasons over the course of the flight. Flight planning adds new challenges as fuel/load and range considerations often create limitations for flights.

With VLJ’s, like other aircraft, pilots may not be able to fill the fuel tanks in order to carry the passenger/baggage load as these high performance aircraft tend to be less tolerant of over-gross weights. Moreover an aft C of G issue could leave your VLJ virtually uncontrollable at lift off and be more critical than the lower performance aircraft you may have flown.

For all jets, you will need to consider the available length of the runway for your take off roll and to clear obstacles with a safe margin. For twin jets, you will want to calculate balanced field length (BFL) and take off "V speeds" to ensure you can either stop on the runway after an engine fails or in the case of sufficient speed continue the take off to go around for a single engine landing.

Perhaps for the first time in your life you will be learning about speeds such as Take off decision speed, Takeoff Safety speed, Design manoeuvring speed, Design Cruise speed, Maximum Operating Limit speed and Maximum Mach number – to name but a few.

After take off, your view will be partially restricted due to the climbing "deck angle" and you will be limited to an indicated airspeed at or below 250 knots below 10,000 feet. This shouldn’t be too much problem for most VLJ’s as their optimum climb speed will likely be below 250 knots. Nonetheless, your view of the area directly ahead may be compromised and this can be a potential collision issue in the often densely populated airport environment.

Because jets are actually normally aspirated engines, the power available drops off with altitude – as does the fuel flow – while the true airspeed increases. These facts when combined essentially provide us the reason that jets fly high – more miles per gallon.

The dropping power means the rate of climb drops constantly and the optimum climb speed may drop with altitude as well. By the time a jet climbs through 18,000 feet its power is approximately halved – and so is the fuel flow.

Since the air is less dense, the indicated airspeed provides a growing "error" because it progressively under-reads the true airspeed (and Equivalent Airspeed – EAS) as the aircraft climbs. For instance, an aircraft like the Diamond D-JET cruising at 180 knots IAS/EAS at 29,000 feet with an OAT of 0 degrees Celsius actually has a true airspeed of 302 knots - cruising almost one half the speed of sound. Which takes us to topic of mach number.

For various reasons, the high altitude airway structure is controlled by airspeeds which are indicated as a percentage of the speed of sound. Thus a mach number of .78 indicates an aircraft that is cruising at 78 per cent of the speed of sound. Common airliner mach speeds at cruise are .72 - .85 with the exception being the Concorde which beat up the air molecules at mach 2.2!

Although the VLJ’s will for the most part be at the bottom of this range – or below it, the normally stated airspeed in the higher levels is reported as a percentage of mach. One of the many topics I won’t get into will be blending the slower VLJ’s into the higher speed airline traffic – or even finding space for them in the airspace.

A conundrum unique to high altitude flight is the "coffin corner." With increasing altitude and engine power dropping the indicated airspeed the wing "sees" for lift is naturally decreasing and in fact may be very close to the stall. Likewise, due to compressibility and the ram pressure of air, the aircraft may be approaching its limiting mach number where airframe buffeting may occur from compressibility potentially inducing airflow separation.

I’m told a B-52 bomber operating at maximum altitude must be flown on autopilot because it is only 5 knots above the stall and 5 knots below high speed buffet onset. Penetration of either the low speed or high speed limit can of course lead to a loss of control. This would be a bad thing and make everyone late for lunch. For that matter, an occupant’s first name would be preceded by "The Late…." Thus the name coffin corner.

Hopeful VLJ margins will be conservative in that manufacturers will likely limit cruising speeds and altitudes to provide safe margins in turbulence and unforeseen events.

Jet power management is rather straight forward with a thrust lever taking the place of a throttle – for each engine. Most VLJ’s won’t have much for complex systems compared to their larger brethren; such as Auxiliary Power Units (APU), reverse thrust, or leading edge high lift devices. However, you will need to become conversant with the pressurization system as it is your body’s lifeline to planet Earth and you will have to ensure the system is on and working properly throughout the flight.

Failure to do monitor this life supporting system adequately could provide you and opportunity to meet with the late golfer, Payne Steward, who perished with all occupants of a Lear 35 that crashed when the pressurization system was not operating. If this system fails at say 16,000 feet in the climb, you and your passengers will have 30 seconds of useful consciousness before you begin to malfunction.

High Performance turbine aircraft typically burn 20-40 per cent of their total fuel load during the first 30 minutes of flight getting to altitude. Over the next few hours of cruising, fuel flow is much lower, but by the time they approach their destination they may only have the minimal legal fuel aboard.

Typically, approaches begin approximately a hundred miles from the destination with a request to begin descent. The pilot in command should only initiate the descent if he is relatively sure the weather at destination is adequate to successfully carry out an approach and landing safely. Otherwise, a diversion to an alternate airport is prudent.

The legal requirement mandates the aircraft must have enough fuel to carry out an approach to destination and in the case of an overshoot then fly to the filed IFR alternate airport plus and additional 15 minutes of remaining fuel calculated at the cruise power setting. This is the minimum and in my opinion – minimal.

Many of these new aircraft will not have "long legs" when it comes to range relative to airliners and pilots will really need to be looking ahead to potentially changing weather at destination for decision making.

They may have chosen an alternate which is close to the destination due to fuel/range capabilities and this can be a problem when unforecast weather closes down a destination and the nearby alternate very quickly.

For instance, it may be necessary for a pilot on a flight from Toronto to Moncton with Fredericton as an alternate to deviate into Montreal for additional fuel if his destination and/or alternate are getting marginal. I came close to participating in an airline accident in a twin jet (whilst occupying the jump seat) on just such a flight years ago when we proceeded to a destination with weather deteriorating below minimums. The last thing you want to do with a jet is arrive at your destination airport in marginal weather that could preclude landing and have your alternate go WOXOF!

Many of Canada’s airports aren’t large enough to land jets and few have instrument approaches. So, picture yourself gliding into a farmer’s field in marginal weather. This would be a very expensive landing that could have been avoided by the thought process of thinking ahead of the airplane.

Readers who have followed my writing for decades will know I have a tendency to talk folks out of aircraft that may be beyond their skill level. But there is more to it than that.

Survivability in a crash is directly related to vertical and horizontal impact speeds into obstacles and our "bods" can take a fair amount of punishment before we succumb.

The break-even horizontal impact speed is approximately 60 mph for a 50/50 survival rate. My motorglider stalls at 45 mph which means that most meetings with the Earth are survivable and even preclude serious injury – although one of my landings a few years ago left me wondering about this.

Jets with their swept, low drag wings are great gliders, but the wing loading is high on these airfoils and stall speeds are typically well in excess of 60 mph making most forced landings onto unprepared surfaces tenuous for occupants. Funerals will likely follow.

I mention this aspect as potential owners need to be aware of this consideration in their risk/reward considerations as a potential "cost" of operating high performance aircraft.

We’ve looked at the survivability of crash landings – and don’t much like the prospects. So, any emergency situation in flight must be quickly contained and typically the jet should be landed at the nearest suitable airport.

Recent history has shown us that even highly trained airline pilots sometimes don’t grasp this importance. Issues such as smoke or fire in the cabin or loss of pressurization or complete power failure will hasten one’s return to terra very firma.

In the case of engine failure for a jet with one powerplant, one becomes a rather efficient glider and I’m guessing the average VLJ will be able to glide a hundred miles from cruising altitude. This gives the pilot lots of time and options to either restart the engine and/or find a suitable airport for landing and troubleshooting.

Incidentally, landing a high performance aircraft without power into a short strip is a challenging adventure that requires exquisite judgment.

The other emergencies named above require maximum rate descents typically at the maximum allowable airspeed. Depending on a VLJ’s complexity, this may require the extension of landing gear, flaps, speed brakes spoilers or other high drag devices to allow the aircraft to get down to the life-giving areas of the atmosphere and land ASAP. Whatever the cause for an immediate descent, the pilot workload will be quite high trouble shooting the problem, getting an oxygen/smoke mask on, declaring an emergency, handling the descent on the edge of the jet’s capabilities and finding a suitable landing area. This will be a handful.

It also dictates that pilots should frequently undergo currency checks that include the broad spectrum of potential emergencies. It is commonplace for pilots to become complacent given the reliability of modern aircraft systems. However, in a jet, it only takes one critical emergency to make the occupants "past tense."

While most, if not all, of these sleek aerial slingshots will be legal to fly single pilot IFR, may I suggest most new owners consider flying with a professional jet pilot or at least a second pilot for a period of time until they get comfortable with the workload during approaches to minimums in inclement weather and other challenging situations. Although that second pilot’s weight may cut down on your aircraft’s useful load, he/she might make all the difference in safely landing/arriving at your destination.

I imagine there may be some resistance to this consideration due to the testosterone impaired judgment of some aviators; however, it is likely that insurance providers will dictate the requirement for a second pilot for owner/pilots who have inadequate experience in the high altitude realm.

It appears there will be a considerable selection of VLJ/PLJ’s available in the marketplace if all the planned companies are able to conduct successful flight testing and certification of their offerings. Cessna, Piper, Diamond, Embraer and Honda are big name manufacturers offering a full range of possibilities to fit most aviators’ needs. Others, such as: Adam, Eclipse, Epic and Excel have their own version of the optimum VLJ and their offerings should be considered as well.

Much of the performance data for many of the jets is unavailable and in my opinion, some of the published performance data is speculative and likely unattainable in some instances. It’s too early for me to comment on recommendations as a result of the preceding and the fact that I haven’t flown any of the new offerings yet.

Some of the facets potential buyers will need to consider include: avionics, useful load with and without full fuel, autopilot capability, range, cruise speed, balanced and short field capabilities, aerodynamic system complexities, direct hourly costs, parking/hangarage capabilities at your home base, insurability of pilot/plane type and your affordability of the true overall costs to own and operate the aircraft.

Each of these could easily warrant a separate article and are simply provided so you can anticipate and research how each topic applies to your needs.

In addition to Nav Canada issues, airport and fuel taxes, CBAA mandatory membership, training and insurance, would-be owners should consider other potential aspects that will ensue if the forecast proclivity of smaller jets comes to fruition.

The flood of aircraft which will be larger than most GA aircraft will create concerns as well on airports in terms of access to fuel pumps, available hangar space for longer wing spans and parking space on the tarmac. Typically, most facilities will not be able to plan adequately for this potential influx of different traffic and problems may create impediment to further growth of this segment for a period of time. Be prepared.

Buying/financing the plane and paying all the federal and provincial taxes is only the tip of the iceberg. Jets aren’t cheap – to buy, to operate, to insure, to hangar, to maintain or to crew.

Nav Canada has already set additional fees to make it unattractive to own and operate a VLJ in Canada. Make sure you create a spreadsheet or at least research the topics to be sure you can truly afford a VLJ.

There are few activities that create more pain than buying an aircraft you can’t afford to operate and having to sell it at a loss. Typically, the only thing a jet aircraft will save you is time. Therefore, the prime reason to buy a VLJ or PLJ should be a need to reduce travel time and provide more personal freedom and time for other pursuits – such as time with family.

Financially, the prime logic for a VLJ should be to free up personal time for individuals who value this commodity more than money. Mind you this consideration will not preclude many folks from buying a light jet to avoid having to fly with the airlines or for show and tell amongst their peers. So be it. That’s the beauty of living in our wonderful country.