V-Speeds: Attitude is Everything

We’ve all heard the phrase, “attitude is everything.” This is especially true for pilots. During your first flight lesson, you probably learned that if you point the nose up, the airspeed goes down, and vice versa. With any luck, your savvy flight instructor taught you how to set the airplane’s pitch attitude using the natural horizon as your reference instead of that tiny little artificial one on the instrument panel. After takeoff, the goal is to climb at a speed that will give you the maximum altitude gained in the shortest amount of time. This is also referred to as the best rate of climb, or Vy.

What does Vy look like? In most light aircraft, a pitch attitude of approximately 10 degrees above the horizon at full power will result in a climb at Vy. To the pilot, it should appear that the top of the instrument panel is even with the natural horizon.

How is the specific airspeed for Vy determined? Presumably, some test pilot working for Cessna back in 1969 was able to achieve the maximum vertical speed in a climb at full power at 73 miles per hour — hence, the published Vy of 73 mph for N60254, a 1969 Cessna 150J. The published Vy for N3370V, a 1975 Cessna 150M, is 78 mph. Why the 5 mph difference in Vy between the two? Who knows. It was the seventies. Both aircraft share basically the same airframe, have the same maximum gross weight capability, and are powered by the same stock 100-hp Continental engine.

In any case, there are many variables that can affect an airplane’s climb performance on any given day, including outside air temperature, altitude, weight, and the overall health of the engine. What you’re after is the best rate of climb that airplane can deliver under the given conditions.

The FAA’s Private Pilot ACS states that during a normal takeoff and climb, the applicant must “establish a pitch attitude to maintain the manufacturer’s recommended speed or Vy, +10/-5 knots.” That’s a pretty wide range. Consider, then, that an applicant flying N60254 can climb at 68-83 mph and an applicant flying N3370V can climb at 73-88 mph to satisfy the ACS. Why not just climb at 75 mph in either aircraft and be done with it?

Vy in other Cessnas in our fleet:

• N152SJ or N152DM (both 1978 Cessna 152): 67 kts (62-77 ACS)
• N65842 (1983 Cessna 172P): 76 kts (71-86 ACS)
• N99725 (1985 Cessna 172P): 76 kts (71-86 ACS)
• N739ZW (1979 Cessna 172N): 73 kts (68-83 ACS)

In practice, we could simply state that Vy is 75 (mph or kts, whichever scale is applicable) in any of our Cessna aircraft and still satisfy the ACS. Then, observe the actual rate of climb achieved at that speed, in that plane, on that day to determine whether you are really getting the most bang for your buck, so to speak.

A similar argument could be made for best glide speed. If the engine quits, you want to pitch for best glide speed — which is going to be ever-so-slightly-nose-down in most light airplanes — and then go about the business of landing the airplane somewhere reasonably hospitable. You are not concerned with a knot here or there, plus or minus from the published speed; you are concerned with doing your best to minimize your rate of descent, which is going to buy you time to restart the engine, run your checklists, and secure the airplane for landing. A good trick is to roll in full nose-up trim, which will get you pretty darn close to best glide speed. Best glide is in many ways similar to best rate of climb, in that you are trying to put time on your side.

Here are the advertised rates of climb for the aircraft in our fleet, at max gross weight, at sea level, on a standard day: N60254 or N3370V, 670 fpm; N152SJ or N152DM, 700 fpm; N65842 or N99725, 700 fpm; and N739ZW, 770 fpm. As any pilot who’s flown a Cessna 150 on a hot summer day knows, you’ll be very lucky to see 500 fpm in the climb to pattern altitude. Plus, unless you’re flying solo with less than full tanks, you’re almost always loaded near or at max gross weight in a Cessna 150, which doesn’t help climb performance. Conversely, if you fly N65842 or N739ZW, with their 180-hp engines and max gross weight of 2,550 pounds, even with full tanks you’re almost always way under max gross weight and will consistently see better than advertised climb performance. 

In conclusion, Vy and its sister speed, Vx — best angle of climb — are approximations, not absolutes. The goal in either case is to do your best, using visual references together with observed aircraft performance, to achieve a safe climb to your cruising altitude, without stalling the airplane or hitting anything on the way up. 

Here’s a video we made a few years ago, that might give you a better perspective on pitching for airspeed. Enjoy!