Before Takeoff Check

It's the systematic AFM/POH procedure for checking the engine, controls, systems, instruments, and avionics prior to flight — normally performed after taxiing to a run-up position near the takeoff end of the runway (AFH ch. 2). The completion standard is unambiguous: all run-up and pre-takeoff checklist items should be completed before taxiing onto the runway or takeoff area, and as a minimum before every takeoff all engine instruments are checked for proper and usual indications and all controls for full, free, and correct movement (AFH ch. 6). Nothing gets finished on the runway.

On a firm surface — smooth pavement or turf if possible — that is free of debris, because the propeller will otherwise pick up pebbles, dirt, sand, or loose objects and hurl them rearward, damaging the propeller and possibly the tail. Small chips in the propeller leading edge form stress risers that can lead to cracks and possible blade failure. Position clear of other aircraft and the taxiway, with nothing behind you that the propeller blast can damage, and headed as nearly into the wind as possible for cooling. Then let the airplane roll forward slightly to align the nosewheel or tailwheel with the longitudinal axis (AFH ch. 2).

Because on the ground, much less air is forced through the cowling and baffling than in flight, and prolonged ground operations may cause cylinder overheating long before there is any indication of rising oil temperature — the gauge you're watching is the wrong one. Mitigation: head into the wind, monitor cylinder head temperatures if equipped, and set cowl flaps per the AFM/POH (AFH ch. 2). Note the opposite constraint too: many engines require the oil temperature to reach a minimum value stated in the AFM/POH before takeoff power is applied.

• Fuel system — set per AFM/POH, verified ON with the proper tank selected
• Trim — set for takeoff, including rudder and aileron trim if fitted
• Flight controls — checked through their entire operating range, full deflection in all directions; the AFH specifically calls out that pilots often fail to exercise full travel, "which is not acceptable"
• Engine — temperatures and pressures in normal ranges, magneto or FADEC operation within limits, carburetor heat functioning, and a constant-speed or feathering propeller exercised with the engine continuing to run normally
• Electrical — voltages in range and the battery system charging
• Vacuum — an acceptable level, typically 4.8 to 5.2 inches of mercury at 2,000 rpm (check your AFM/POH)
• Flight instruments — rechecked and set, directional gyro and magnetic compass in agreement, heading bug to the runway or assigned heading
• Avionics — frequencies, initial nav source and courses, autopilot preselects, transponder code (AFH ch. 2)

Because mechanical gyroscopic instruments need adequate time to spool up to acceptable rpm before they indicate properly. A quick taxi and rushed run-up doesn't give them that time — and the AFH's conclusion is pointed: under those circumstances "a departure into instrument meteorological conditions (IMC) is unadvisable" (AFH ch. 2). Commercially this is the rushing-because-someone-is-waiting failure with a specific consequence attached.

Yes. The AFH is explicit that the takeoff briefing is made out loud by the pilot even when no other person is there to listen, and that it should include a visual verification of the correct surface and direction to preclude a wrong-surface departure (AFH ch. 2). Saying it out loud pre-loads the decision, so a failure gets action instead of deliberation.

Following the AFH's sample structure: type of takeoff (normal, short, or soft); runway assigned; wind direction and speed; rotation speed (the manufacturer's or calculated V_R); initial turn heading and initial altitude; then the emergency plan by phase —

• Engine failure below V_R — reject, apply appropriate braking, stop ahead
• After V_R with runway remaining — lower pitch, land, brake, stop straight ahead
• After V_R with no runway remaining — lower pitch to best glide, no turns prior to a stated altitude, land in the most suitable area, brake, avoid ground hazards; turn back to the runway only at or above a stated AGL altitude, converted to MSL
• If time permits — fuel, ignition, and electrical systems off (AFH ch. 2)

Before beginning the roll, confirm that the runway numbers agree with the magnetic compass and heading indicator. Then as power comes to full takeoff power (AFH ch. 2):

1. Doors latched and windows closed as required?
2. Controls positioned to account for any crosswind?
3. Power correct?
4. Engine rpm normal?
5. Engine smooth?
6. Engine instruments normal and in the green ranges?

The decision, not the technique. Avoidance technique on the roll and climb is covered under Task IV.A; what has to happen before you ever release the brakes is:

• Decide whether to accept the departure at all. Waiting behind a large, heavy airplane costs you minutes; the AFH names the consequence of getting it wrong as a possible loss of control at an altitude with no recovery margin (AFH ch. 6)
• Decline the "no delay" or "immediate" departure if the spacing you want isn't there. You are never obligated to accept a clearance that compresses your own margin, and a commercial pilot with a paying passenger has more reason to say "unable," not less
• Brief the rotation point while you're still stopped, because you cannot compute it during the roll

The examiner is testing whether the pressure to keep the flight on schedule is what moves your decision. It shouldn't be.

Re-do the work, not just the taxi:

• Runway length and surface condition — checked against your required distance
• Wind components — recomputed; a crosswind can become a tailwind in one instruction
• Obstacle and terrain picture — off the new departure end
• Emergency plan — rewritten, because the land-ahead options and the turn-back altitude are runway-specific

Re-brief it out loud with the new numbers. If it doesn't work, "unable" is the answer, and the taxi route and hot-spot review start over (Task II.D).

• That a drop occurs at all. No rpm drop on a mag suggests the ignition wasn't actually isolated — a broken P-lead leaves that magneto hot regardless of switch position, which is the same failure that makes a "dead" propeller dangerous (AFH ch. 2, hand-propping discussion).
• The size of the drop. An excessive drop or rough running points to a fouled plug, a failing magneto, or timing outside limits.
• The split between the two. A large difference means one ignition system is unhealthy even when both drops are individually inside the POH limit.

Compare all three against the AFM/POH numbers for your airplane — the limits are type-specific and are not something to carry over from a different airframe.

Diagnose once, then decide. A lead-fouled plug will often clear by leaning aggressively at moderate rpm per the POH and rechecking; if it clears fully and the split returns to limits, the cause is understood. If it doesn't clear, or you find yourself on the third attempt inventing reasons the number is acceptable, the airplane goes back to the ramp. The commercial framing: an ignition system that is marginal on the ground with 5,000 feet of runway ahead is a system you have chosen to test again at 200 feet AGL.

Because the airplane isn't necessarily stationary. The AFH's reason: if the parking brake slips, or toe brake application is inadequate for the power applied, the airplane could rapidly move forward and go unnoticed if pilot attention is fixed only inside. The recommended operational practice is to split attention from one item inside to a look outside (AFH ch. 2). Add the traffic picture — aircraft on final, aircraft taxiing up behind you — and your own position relative to the hold line.

Answer, then back up several items and re-run them rather than resuming from where you believe you stopped. Interruption is the documented mechanism by which checklist items get skipped, and the ACS builds distraction into the test deliberately: evaluators are directed to incorporate realistic distractions to evaluate situational awareness and the ability to divide attention inside and outside the flight deck (ACS Appendix 2). Handling the interruption gracefully and then visibly recovering the checklist is the behavior being graded.

Compare the assumptions to what's actually true right now:

• Wind — current versus the wind you planned on
• Temperature and altimeter setting — current versus the density altitude you computed
• Runway — the one you're actually assigned, and its surface condition
• Weight — what the airplane finished up at after the last-minute bag

Density altitude is the variable that moves fastest and hurts most — it decreases engine and propeller performance, increases takeoff roll, and decreases climb performance (AFH ch. 6). If the recomputed numbers no longer leave margin, the run-up area is the last cheap place to say so.

As a set of operational factors you evaluate for this departure, in the ACS's own order:

• Airplane characteristics
• Runway or takeoff path length
• Surface conditions
• Environmental conditions
• Obstructions

The AFH adds the decision content — consider the available options if an engine failure occurs after takeoff, including the preferred direction for emergency turns to landing sites based on the departure path, altitude, wind conditions, and terrain (AFH ch. 6). That survey is what produces the specific altitudes and headings you then speak in the takeoff briefing; a briefing without it is a recitation.