Aviation Safety Corner
this month's topic, I would like to conclude our discussion on, "Initial Climb Strategies." Exploring
the pros and cons of using your airplane's best-rate versus best-angle climb speed after liftoff. This is Part
IV of IV.
Now let's discuss, "Trust the Table?" The trouble with airspeed correction tables and graphs are that they are generally calculated by flight-testing the airplane in level flight at minimum airspeed at which it is safely flyable and at power required for that particular level flight.
The tests probably never were done at airspeeds closer than 10 mph above stall speed for that particular configuration. They probably never were done at the actual full-power stall airspeed. And the tests never were done at full-idle power, except, maybe, during instrumented stall speed tests (with a special pitot/static swivel-head boom) and then only to get a stall-speed, not an airspeed-correction data point. The point: No matter what brand of airplane you fly, don't trust the CAS vs. IAS calibration at near stall airspeed. Before you ever attempt a Vx climbout, you already should have practiced the maneuver at some higher altitude. You must know the pitch attitude for the Vx climb under similar density altitude and weight conditions.
That Vx is on the backside of thrust and power-required curves, and not something you can search for after lifting off with a full load from Mount Baldy.
Now, let's discuss, "Snapping Point." Whether you're in a single or a twin that Vx climbout is just asking for trouble. You risk the loss of all climb rate and climb angle if you just get the nose too high and slow the airplane below Vx. Even worse, you risk a real hard crash if an engine burps during the initial climb.
A Vx climbout should be considered a do-it-right-or-die maneuver. It shouldn't be done intentionally with passengers aboard. Should you know how to perform a Vx climbout? Definitely. Just imagine taking off from a runway that's fairly short, but still long enough for a normal takeoff and Vy climbout. During initial climb at Vy, though, things don't look right. Those trees and power lines aren't falling under the nose like they always have before. They are staying in the same lower part of the windshield.
Maybe you departed with an unknown tailwind. Maybe your engines aren't putting out full power. Whatever the reason, if there isn't runway remaining on which to land, you had better be ready to transition to Vx real quick. You had better have recently practiced that Vx climb at some slightly higher density altitude. You will have to set both a higher climb pitch attitude and slower airspeed quickly and accurately.
Now, let's discuss, "Sudden Upset." While we're on the subject of maneuvers that you might have to do someday, let's consider one that you probably have never practiced in "Old Bessie," "Little Betsy" or "Twin Boomer." This maneuver would be necessary after a sudden upset in an encounter with bad turbulence or vortices from a big airplane. If you encounter this situation, you better know how to recover fast and quickly. You may ask, all this talk about recovering from a roll upset doesn't have much bearing on Vy versus Vx. But it does pertain to another part of your airplane's performance envelope, and you should know how to handle it.
We still experience too many accidents when "something bad" happens that is within an airplane's performance envelope for recovery, but outside the pilot's "envelope" of knowledge, training and practice. Too many of us are prepared only for normal operation and not ready for emergency situations that could (and do) happen.
Let's finish by considering, once again, the subject of initiating a go-around at the last minute of a landing approach or, maybe after you've already touched down.
We still see too many accidents from "long/hot" landings that end up with airplanes off the far ends of runways. Whether it's a long landing because of a botched approach, excessive airspeed or a tailwind, you can almost always go around. Even on very short final or after the wheels have touched the runway, you can still execute a waveoff, so long as there is sufficient room ahead.
But, remember just like the Vx climb or the roll to recover from an upset, it's something that needs a little bit of practice. Once again, this is an "abnormal" maneuver that needs some practice up considerably higher than ground level. And again, there will be pitch attitudes to memorize and airspeeds to peg for the initial climb.
The Bottom Line: If your airplane can do it, then you as PIC, should know how to do it. Don't miss next month's Aviation Safety Corner, when I'll start a new discussion, "Set Up For Success." Here's how to make your flying safer, more efficient and more effective. This will be a four part series.
Larry G. Harmon
FAA AVIATION SAFETY COUNSELOR
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