Take-off
Take-off is one of the most critical phases of flight. Low altitude, full power, speed near stall — errors here turn into accidents fastest.
Take-off speeds (V-speeds)
| Symbol | Meaning | Source |
|---|---|---|
| Vr | Rotation Speed | POH |
| Vlof | Lift-off Speed | POH |
| Vy | best rate of climb (most altitude per time) | POH |
| Vx | best angle of climb (most altitude per distance) | POH |
| V₁/V₂ (twin) | critical engine failure speed / take-off safety speed | POH; primarily multi-engine |
Example C172: Vr ≈ 55 KIAS, Vy ≈ 79 KIAS, Vx ≈ 64 KIAS.
Take-off procedure — standard (normal take-off)
- Line up: nose aligned, yoke neutral, brakes off.
- Throttle smooth full forward (3 seconds).
- Engine check: full RPM, manifold pressure (constant speed), no red T&P values. If abnormal: abort.
- Acceleration: pilot checks runway movement, keeps centreline with pedals.
- Rotation at Vr: light yoke back → nose up → lift-off.
- Initial climb at Vy (or Vx if obstacles).
- Gear retract (retractable): after positive climb.
- 500 ft AGL: flaps in (if take-off flaps), "after take-off check".
Take-off configurations
Normal take-off
- Paved runway, no obstacle.
- Flaps 10° (POH).
- Accelerate to Vr, rotate.
Short-field take-off
- Short runway or obstacle at the end.
- Flaps 10–20° (POH).
- Hold brakes while throttle full, release.
- Rotate at Vx, climb at Vx until obstacle clear, transition to Vy.
- Best obstacle clearance.
Soft-field take-off
- Grass, snow, mud runway.
- Flaps are set to the value specified in the flight manual (POH) for soft-field take-off — typically 10° in the C172, other values for other aircraft. Never "any flap setting" — the precise configuration is POH-specific.
- Yoke fully back while rolling → nose up, less wheel friction.
- Lift-off as early as possible (ground effect).
- In ground effect accelerate to Vy, then climb.
Crosswind take-off
- Ailerons full into wind at standstill.
- During acceleration: reduce aileron as control surfaces become effective.
- Rotate slightly before Vr (slightly earlier than normal): avoid single-wheel lift-off.
- Once airborne: light slip into wind → no sideways movement.
TODR (Take-off Distance Required) — influencing factors
When calculating the required take-off distance, the following factors must be considered — all stated in the POH performance chart:
| Factor | Effect |
|---|---|
| TODR from POH chart | base value for standard conditions |
| Pressure altitude | higher PA → longer TODR (lower air density) |
| Temperature (OAT) | higher temp → longer TODR (lower air density) |
| Runway slope | upslope → longer TODR; downslope → shorter |
| Runway surface condition | grass, snow, slush, wet → longer TODR (see lesson "Contaminated Runways") |
| Wind | headwind → shorter TODR; tailwind → longer |
| Weight (take-off mass) | more weight → longer TODR (squared effect) |
Runway availability must be at least TODR + 25 % reserve (AOPA recommendation; POH gives TODR without reserve).
Aerotow / glider tow start
On aerotow (a powered aircraft tows a glider) the take-off distance of the towing aircraft lengthens due to the additional load. The TODR increase on aerotow is further increased by the following factors:
- Upslope runway: longer roll, less acceleration.
- Tailwind: higher ground speed required for same IAS lift-off → longer distance.
- High outside air temperature: lower air density → less lift → longer acceleration.
- Low atmospheric pressure: also lower air density → longer TODR.
All four factors act cumulatively to extend aerotow take-off distance. The pilot computes the combined TODR together with the glider club before the aerotow and compares it with the available runway.
Engine failure on take-off
Pre-flight briefing (see run-up):
- Before Vr / still on runway: throttle idle, brakes, runway stop.
- After Vr / lift-off, < 500 ft AGL: continue straight, emergency landing route, no turn back ("Impossible Turn").
- Above 500 ft AGL: emergency-field selection, best-glide speed, possible turn back (see Subject 070 lesson "EFATO").