If you're working toward your Commercial certificate, you already know your V-speeds. You've had them memorized since private pilot training. But here's the thing — on a commercial checkride, the DPE isn't just going to ask you what Vₐ is. They're going to ask you why it changes with weight. They'll want to know what happens to Vₓ and Vᵧ as you climb. They'll expect you to connect the numbers to the aerodynamics behind them.
This is where a lot of commercial candidates stumble. Not because they aren't smart, but because nobody ever pushed them past the chart. Let's fix that.
V-Speeds Are Not Fixed Numbers
This is the first mental shift you need to make. When you pulled out the POH during private pilot training, you probably saw a clean table — one set of speeds, nice and tidy. But most of those published V-speeds are based on maximum gross weight. The airplane you're actually flying on any given day is rarely at max gross.
That matters because V-speeds are rooted in aerodynamics, and aerodynamic forces change with weight. A lighter airplane needs less lift to maintain flight, which means it can fly slower before it stalls and reaches critical limits sooner at the high end. When the weight changes, the speeds shift with it.
Think of it this way: the POH chart is a snapshot. Your job as a commercial pilot is to understand the full picture.
Why Vₐ Changes With Weight
Maneuvering speed (Vₐ) is probably the most commonly tested example, and for good reason — it's the V-speed that changes most noticeably with weight.
Vₐ is the maximum speed at which you can apply full, abrupt control deflection without exceeding the airplane's load factor limits. Here's the key: at Vₐ, the airplane will stall before it bends. Apply a sudden full deflection, and the wing reaches its critical angle of attack and stalls before the structure takes excessive load.
Now picture the airplane 300 pounds below gross weight. It's lighter, which means it needs less lift in straight-and-level flight. If you apply that same abrupt input at the same speed, the wing can now generate more excess lift relative to the airplane's weight before it stalls — which means a higher load factor. That could exceed the structural limit.
So Vₐ decreases as weight decreases. A lighter airplane reaches its structural limits at a lower speed. Many POHs publish Vₐ at multiple weights for exactly this reason. If yours doesn't, you should be able to explain the relationship verbally on your checkride. Check your specific airplane's POH for published Vₐ values at varying weights — some POHs include a chart or table, others list only the max gross weight value.
Vₓ and Vᵧ: What Happens as You Climb
Best angle of climb speed (Vₓ) and best rate of climb speed (Vᵧ) are two more speeds that don't stay put — but for a different reason.
Both of these speeds are defined by the relationship between the airplane's power available and power required. As you climb and the air gets thinner, the power available from your normally aspirated engine drops off while the power required curve shifts. The result:
- Vₓ increases with altitude
- Vᵧ decreases with altitude
- At the airplane's absolute ceiling, the two speeds converge into a single value
This convergence point is worth understanding conceptually. At the absolute ceiling, there's only one speed at which the airplane can sustain level flight. There's no excess power for climbing — best angle and best rate become the same thing because there's nothing left to optimize.
Imagine you're departing a high-elevation airport on a hot day. Your density altitude is already eating into your performance. Knowing that Vₓ and Vᵧ are shifting means you're not blindly holding sea-level numbers — you're thinking about what the airplane can actually give you right now. That's commercial-level decision-making.
Vₛₒ, Vₛ₁, and the Stall Speed Relationship
Stall speeds (Vₛₒ in landing configuration and Vₛ₁ clean) also change with weight, and the relationship is straightforward: less weight means a lower stall speed. The wing simply doesn't need to produce as much lift, so it reaches its critical angle of attack at a slower airspeed.
This has practical consequences. If you're calculating approach speeds, reference speeds, or maneuvering margins, you should be thinking about your actual weight, not just the published max-gross numbers. A 1.3 × Vₛₒ approach speed is a different number at 2,100 pounds than it is at 2,550 pounds.
This also connects to load factor. Remember, stall speed increases with load factor — in a 60° banked turn, the stall speed increases by roughly 41% regardless of weight. If you're already light and slow, that margin shrinks faster than you might expect.
How to Talk About This on Your Checkride
The Commercial Pilot ACS expects you to demonstrate understanding of performance concepts, not just recite numbers.
Here's how to approach it:
- Know the relationships. Vₐ decreases with weight. Vₓ and Vᵧ converge with altitude. Stall speeds decrease with weight. Be able to explain why for each one.
- Use your POH. When the DPE asks about V-speeds, have the relevant charts and tables ready. Show that you know where to find adjusted values and that you understand what drives the adjustments.
- Connect it to decision-making. The DPE wants to see that you'll apply this knowledge operationally. Talk about how you'd adjust your approach speed on a light-weight flight, or why you'd reference a lower Vₐ in turbulence when below gross weight.
If you're looking for structured practice on commercial oral topics like this, the ASA Commercial Oral Exam Guide walks through the kinds of questions DPEs actually ask — including performance and aerodynamics scenarios that go beyond simple recall.
The Bottom Line
V-speeds aren't just numbers on a laminated card. They're aerodynamic boundaries that move with your airplane's weight, configuration, and environment. As a commercial pilot candidate, your job is to understand what's behind those numbers well enough to explain it clearly and apply it in the cockpit.
That shift from memorization to understanding is what separates the commercial certificate from everything before it. Nail this, and you'll walk into your checkride with the kind of confidence that comes from actually knowing the material — not just remembering it.
For more resources to support your commercial training, visit NorthstarVFR.com.