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Positive Rate

I was climbing on top of the fog, looked down at my instruments, and when I looked up I saw the power lines... Miraculously, all three aboard the Beech Bonanza escaped injury when the slick six-seater hit the power lines and slammed into a pasture. The aircraft was consumed in a post-crash fire.

"I was climbing on top of the fog, looked down at my instruments, and when I looked up I saw the power lines..."

Miraculously, all three aboard the Beech Bonanza escaped injury when the slick six-seater hit the power lines and slammed into a pasture. The aircraft was consumed in a post-crash fire. According to the NTSB, the flight was conducted under instrument flight rules and launched into a thin layer of fog that limited surface visibility to a quarter mile and obscured the skies with a 100-foot vertical visibility. These were very low instrument meteorological conditions (IMC). The pilot received his clearance and took off, planning to climb to visual meteorological conditions (VMC), then proceed "on top" in clear skies to his destination. But the flight only made it a mile and a half from the airport.

Early in our flight training we're taught to "rotate," or pull the nose up for takeoff, at an identified airspeed, then establish an airspeed that provides the desired climb performance. Pilot's Operating Handbooks (POHs) give two (and sometimes three) recommended climb speeds -- Vx, or best angle of climb airspeed; Vy, best rate of climb; and sometimes Vcc, best cruise climb airspeed. POHs for multiengine airplanes will additionally list Vxse (best angle of climb, single engine) and Vyse (best rate of climb, single engine -- the "blue line" airspeed). Establish one of these airspeeds and the airplane will obtain the best possible performance for the desired operation (climbing at the greatest angle, at the greatest rate, or, for cruise climb, at a good rate with additional forward airspeed for engine cooling and en route groundspeed). Any other airspeed will result in less-than-optimum climb.

Insider's Tip: These POH listed airspeeds are almost always given for the maximum takeoff weight of the airplane. Most speeds are reduced by about 2% for every 100 pounds below maximum takeoff weight. A lightly loaded airplane, then, gets best climb performance at speeds slightly lower than "book" speeds if loaded below maximum. In most training-type airplanes the difference is negligible. In airplanes with a wide range of operating weights, however, the difference is quite noticeable. Check it out yourself -- on a calm, clear day, get some altitude, then establish takeoff power and "book" airspeeds. Record performance (vertical speed). Then try a slightly lower airspeed and see if steady-state (rate after any initial "zoom") performance improves.

Danger: Soon the flight student realizes it's hard to rotate to a precise airspeed on takeoff, since the indication lags somewhat. He or she will quickly find a visual pitch attitude that nets the desired air speed -- learning to bring the nose up to here for a "normal" takeoff (usually Vy), and there for an obstacle-clearing Vx airspeed. Once the student makes this correlation it's easy to establish precise climb attitudes, knowing the airspeed will inevitably follow and the airplane will get its optimum climb performance. After a while it becomes natural.

By the time the pilot begins instrument training (especially if he/she has experience in the type of airplane used for training), the "tug" needed to establish climb is almost instinctive. Instrument instructors may see the pilot repeatedly "acing" the desired climb speed and think the student knows what pitch attitude is required for a low-visibility takeoff. In fact, the pilot is establishing pitch primarily by reference to the outside world. "Zero-zero" takeoff training (simulating takeoff in dense fog or otherwise reduced visibility) is usually more concerned with maintaining runway centerline and heading after rotation, and not a precise climb attitude. "Zero-zero" instrument takeoffs are risky, and most instructors warn their students against them. The reality is that a pilot may train for as few as one simulated instrument takeoff in an entire course of rating training ... ready to fly IFR in all cases except the actual low-visibility takeoff.

Zero-Zero Key: Pilots must know what indicated pitch attitude (on the artificial horizon, or using more modern terminology, the attitude indicator) equates to Vx, Vy and Vcc -- then establish and hold that pitch attitude until well clear of the ground.

Example: Except at very high density altitudes, a typical piston airplane achieves Vx airspeed at about 10-degrees up indication; Vy comes at around seven-degrees up; and cruise climb is usually at about five-degrees above the horizon. Establish 10-degrees up for the first 50 feet (or clear of obstacles), lower to seven-degrees up for initial climb, then establish five-degrees up for cruise climb when passing 1000 feet above ground level. "Flight test" your airplane to see what works best for you.

Once you've established climb attitude, maintain that pitch until you know you're safely above obstacles. Be especially careful to compensate for distractions while close to the ground. Leaning forward to reach a landing gear switch, for instance, may cause you to unknowingly ease forward on the control yoke -- reducing climb performance at best, and at worst putting the airplane into a descent close to obstacles you can't see. Flap retraction, in addition to the "reach and push" potential, may aerodynamically cause the airplane to pitch either up or down, taking it away from the optimum climb attitude, speed and rate. Fixation on tuning radios can cause the same effect, as can reaching for a microphone (although I've done it, handheld microphones and IMC don't mix, in my opinion). Glimpses of the ground as you streak in and out of clouds or fog may invite you to subconsciously steer downward toward them; looking down at charts or your kneeboard will almost certainly make you deviate from pitch attitude, usually down.

Instrument takeoffs are risky, but not unmanageably so. Some simple actions will minimize the risk...

  • Pass the blindfold cockpit check. In the Air Force we had to be able to identify every control, switch and gauge in the cockpit, on demand, while sitting blindfolded in the cockpit -- before we were allowed to solo. The blindfold cockpit check should be a part of all instrument flight training, and for anyone contemplating flying at night in visual conditions also. If you can't pass a blindfold cockpit check in the airplane you're flying, take the time to get familiar before launching into dark or instrument conditions.
  • Learn the pitch attitudes for Vx, Vy and Vcc (Vxse and Vyse for twin drivers, too) in the airplane you're flying. Flight by reference to instruments, especially close to the ground, needs to be done with precision. "About like this" needs to be replaced with "ten degrees up until reaching 1000 feet, then seven degrees up for climb."
  • Avoid distractions. Tune your radios before takeoff. Learn the initial climbout information from charts before taking the runway for departure, so you won't need to look at them again until you're well clear of the ground. Watch your attitude indicator (to maintain pitch) instead of physically looking at your gear or flap switch as you clean up for climb (here's where that blindfold cockpit check comes in handy). Invoke the "sterile cockpit rule" when within the takeoff "altitude critical area," the first 1000 feet above ground (see The Big Ground Theory And The ACA Defense).
  • Practice in visual conditions, so this will all be habitual when you're in IMC. Make every takeoff as if you're in a high-workload, instrument environment. Look outside for traffic and obstacles, of course, but plan ahead, and fly your plan, so you'll be ready when you want to try an instrument takeoff.

Note: There's nothing that limits these recommendations to instrument flights only. Night pilots, and even those flying visually in the day, need to maintain a positive rate of climb just after takeoff.

BOTTOM LINE: Know and practice precise techniques to get positive climb performance from your airplane. Don't attempt instrument -- or night -- takeoffs in an airplane with which you're not intimately familiar. Actively work to minimize distractions close to the ground -- that means planning. And remember this: Chances are you wouldn't be as lucky as the three that walked away from that Bonanza crash.

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About This Author:
Tom Turner is a widely published author and regular forum speaker at EAA's Oshkosh/Airventure and American Bonanza Society. Tom holds an M.S. in Aviation Safety with an emphasis on pilot training methods and human factors. He has worked as lead instructor at FlightSafety International, developed and conducted flight test profiles for modified aircraft and authored three books including: Cockpit Resource Management: The Private Pilot's Guide and Instrument Flying Handbook (both from McGraw-Hill). His flight experience currently spans 3000 hours with approximately 1800 logged as an instructor. Tom's certificate currently shows ATP MEL with Commercial/Instrument privileges in SEL airplanes.
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