Principles & why

A normal takeoff combines three principles that recur in every Area IV task: V-speed selection for climb performance, pitch-for-airspeed control discipline, and left-turning tendencies on a propeller-driven airplane near full power.

Why V_Y for initial climb

V_Y is the airspeed that produces the maximum rate of climb — the most altitude gained per minute. It's where the excess thrust horsepower is largest: the difference between thrust horsepower available (from the engine) and thrust horsepower required (to maintain level flight).

V_X (best angle of climb) is slower than V_Y — it gives the maximum altitude per unit of horizontal distance. V_X is used for obstacle clearance on short-field departures (E) where you need to clear something close to the runway end. For a normal departure, V_Y wins because it gets you out of the traffic pattern faster.

Default view: V_Y only — the normal-takeoff profile. Switch to "Compare" to see V_X overlaid; it's steeper but slower over the ground. For the V_X-then-V_Y short-field sequence (E's task), see the V_X → V_Y mode.

Both V-speeds decrease as altitude increases because thrust horsepower available falls faster than horsepower required as the air thins.

Pitch for airspeed, power for altitude

On the takeoff climb at constant takeoff power:

• Pitch attitude controls airspeed (you trim for V_Y by setting a specific pitch attitude).
• Power controls altitude (the throttle is already at takeoff, so altitude rate is what it is).

This inverts what students sometimes expect ("I'll climb faster if I pitch up more" — wrong; you'll slow down and climb less). Set the pitch attitude that gives V_Y, hold it with trim, and let the airplane climb at whatever rate the airplane chooses for the conditions.

Left-turning tendencies

At full power and high angle of attack — exactly the takeoff regime — a propeller-driven single produces four yaw-left tendencies, summarized by the mnemonic PAST:

• P-factor: descending propeller blade (right side, on most US engines) takes a bigger bite of air than the ascending blade (left side), producing left yaw. Strongest at high alpha + full power.
• Accelerated slipstream: the propeller's helical airflow strikes the left side of the vertical stabilizer, pushing the tail right (nose left).
• Spiraling slipstream: the same effect, longer name.
• Torque: Newton's third law on the engine's rotation — the propeller spins clockwise (from the cockpit), the airplane wants to roll left, and the wheel-on-the-ground contact resists, transferring it to yaw.

Total result: a normal takeoff requires right rudder to track the centerline. Forget it and the airplane drifts left.

Why we confirm the runway

V.A.S1 requires verifying the assigned or correct runway before takeoff. Wrong-runway takeoffs are a documented runway-incursion category and a frequent NTSB report. The check is:

1. Read back the clearance.
2. Check the runway numbers on the threshold.
3. Check the heading bug matches the runway.

Three independent confirmations of the same fact. The redundancy exists because each individual check can fail — the bug can be wrong, the numbers can be misread, the clearance can be misheard — but all three failing at once is rare.

Why "smooth power"

V.A.S3 specifies smooth power application. Two reasons:

• Engine longevity. Slamming the throttle subjects the engine to thermal and mechanical shock; smooth application is gentler.
• Directional control. Sudden power application is a sudden left-yaw torque pulse — harder to coordinate with rudder than a gradual rise.

Three to four seconds from idle to full is gentle enough to be smooth, fast enough not to waste runway.