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Commercial pilot · ACS CA.II.F · lesson pack

Before Takeoff Check

Why this one matters

The run-up is the last chance to find a problem on the ground, and the takeoff briefing is the decision you won't have time to make later. In a heavier, faster complex airplane, with passengers aboard, both carry more weight.

1 · Know these cold

  • •Run the before-takeoff checklist by the POH, and know what each item tells you about the airplane.(Airplane Flying Handbook (FAA-H-8083-3C), Ground Operations)
  • •Magneto check: the RPM drop on each, and the difference between them, within the POH limits, with smooth running. An excessive drop or roughness, too large a difference, or no drop at all (a magneto not grounding) means don't fly.(Airplane Flying Handbook (FAA-H-8083-3C), Ground Operations)
  • •Constant-speed propeller: cycle it at the run-up RPM per the POH to check the governor and circulate warm oil to the hub.(Airplane Flying Handbook (FAA-H-8083-3C), Transition to Complex Airplanes)
  • •Review takeoff performance for the runway in use; re-check it if the runway changes.(Commercial Pilot ACS (FAA-S-ACS-7B), CA.II.F.S1)
  • •Divide attention: eyes outside during the run-up, brakes firmly held.(Commercial Pilot ACS (FAA-S-ACS-7B), CA.II.F.S4)
  • •Brief the takeoff: speeds, an abort point, and the plan for an engine failure on the runway, at low altitude and higher up.(Airplane Flying Handbook (FAA-H-8083-3C), Ground Operations)
  • •Departing behind a larger airplane: note its rotation point, rotate before it, climb above its path until you turn clear of its wake, and avoid headings that cross below and behind it; or wait (at least 2 minutes).(AIM, Chapter 7, Wake Turbulence)

2 · The lesson

What the checklist is checking
  • Run-up at the POH RPM: magnetos, carburetor heat or alternate air, oil temperature and pressure, suction, ammeter or load meter.(Airplane Flying Handbook (FAA-H-8083-3C), Ground Operations)
  • Propeller: at the POH run-up RPM, pull the control back: RPM drops, manifold pressure rises, and oil pressure dips briefly; push it forward and all three recover. No RPM drop means it isn't governing: don't fly.(Airplane Flying Handbook (FAA-H-8083-3C), Transition to Complex Airplanes)
  • Flight controls free and correct; flaps and trim set for takeoff; fuel selector, boost pump and mixture set per the POH (leaned for density altitude if specified).(Airplane Flying Handbook (FAA-H-8083-3C), Ground Operations)
  • Instruments and avionics set: altimeter, heading indicator, frequencies, transponder, flight plan in the GPS.(Airplane Flying Handbook (FAA-H-8083-3C), Ground Operations)
  • Doors and windows latched, belts and harnesses fastened, passengers briefed for the sterile departure.(Airplane Flying Handbook (FAA-H-8083-3C), Ground Operations)
Attention and runway changes
  • Position for the run-up on a firm surface free of debris, clear of other aircraft, people, vessels and buildings, with the propeller blast pointed at nothing it could damage, headed as nearly into the wind as possible (for cooling and stability); roll forward a little after stopping so the nosewheel is straight.(Commercial Pilot ACS (FAA-S-ACS-7B), CA.II.F.S3; Airplane Flying Handbook (FAA-H-8083-3C), Ground Operations)
  • Look outside often during the run-up: the airplane can creep and traffic moves around you.(Commercial Pilot ACS (FAA-S-ACS-7B), CA.II.F.S4)
  • If ATC changes the runway, re-check takeoff distance and the departure, and say "unable" if it doesn't work.(Airplane Flying Handbook (FAA-H-8083-3C), Ground Operations)
Wake turbulence
  • Vortices are strongest behind heavy, clean, slow airplanes; they sink and drift with the wind.(AIM, Chapter 7, Wake Turbulence)
  • Behind a departing larger airplane, all of these: note its rotation point, rotate before it, climb above its climb path until you can turn clear of its wake, and avoid later headings that cross below and behind it. Otherwise wait.(AIM, Chapter 7, Wake Turbulence)
Planning for a failure
  • Brief two abort triggers: not at the briefed speed by the briefed point (set from runway length, surface, density altitude and obstacles); and any engine failure, abnormal indication or other malfunction anywhere in the roll before liftoff. Either one: throttle idle, brakes, stop straight ahead.(Airplane Flying Handbook (FAA-H-8083-3C), Ground Operations)
  • Engine failure on the runway: power to idle, brakes, and stop straight ahead.(Airplane Flying Handbook (FAA-H-8083-3C), Ground Operations)
  • Engine failure after liftoff at low altitude: lower the nose to hold glide speed and land ahead or within small turns. In a retractable, gear and flaps per the POH for the landing.(Airplane Flying Handbook (FAA-H-8083-3C), Ground Operations)
  • A turn back needs much more than 180° (about 225° to line up again) and often ends in a downwind landing. Know your airplane's real altitude loss from practicing at a safe altitude (one AFH example lost about 1,300 feet); never brief a guessed round number. Below it, land ahead.(Airplane Flying Handbook (FAA-H-8083-3C), Ground Operations)

Want it all on one page, with scenarios? Read the full lesson.

On the flight

ACS standards

  • Review takeoff performance; complete the checklists; position the airplane for wind and nearby aircraft, vessels or buildings.(Commercial Pilot ACS (FAA-S-ACS-7B), CA.II.F.S1-S3)
  • Divide attention inside and outside; verify engine parameters and configuration are suitable.(Commercial Pilot ACS (FAA-S-ACS-7B), CA.II.F.S4-S5)

What your instructor is watching for

Your instructor watches for a checklist-driven run-up including the propeller check, eyes outside, correct interpretation of the magneto and propeller checks, and a clear takeoff briefing with an abort point and engine-failure plan.

3 · Say it out loud

Answer each one out loud, then check yourself and mark how it went.

  1. Remember Recall it

    “Why do you cycle a constant-speed propeller during the run-up?”

  2. Understand Explain why

    “Why set an abort point before takeoff?”

  3. Apply Use it on a flight

    “Tower changes you to a shorter runway on a hot day with full seats. What do you do?”

4 · Common mistakes

  • Skipping the propeller cycle or doing it too quickly.

    A governor fault is found on the ground or in flight.

    Instead: Cycle it per the POH and watch RPM and oil pressure respond.

  • A takeoff briefing without an abort point.

    Without one, a slow acceleration is noticed too late.

    Instead: Brief an abort point and speed every time.

  • Accepting a runway change without checking performance.

    The new runway may not work today.

    Instead: Re-check, then accept or say "unable".

5 · Quick check

Answer, then reveal. Flag anything you want to see again.

  1. 1. What does the magneto check look for?

  2. 2. Which way should the airplane point during the run-up?

  3. 3. Where are wake vortices strongest?

  4. 4. What is the first action for an engine failure on the takeoff roll?

  5. Scenario5. The propeller doesn't respond during the run-up check. Do you go?

Trained it? Now prove it: practice before takeoff check out loud with our examiner.

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Connect it

One situation that runs across this lesson and its neighbors in the same ACS area. Decide first, then check.

Connect it · Preflight Procedures

A retractable-gear airplane with a constant-speed propeller. During preflight you find fresh hydraulic fluid near the nose gear. Three passengers are boarding.

How do the preflight finding, the passenger briefing and the before-takeoff check connect? Decide, then see the worked answer

Stop the boarding and keep the passengers clear of the airplane until a mechanic has inspected the fresh fluid near the gear and you, as PIC, have determined the airplane is airworthy. A failed gear system changes every landing. Once it's cleared, review the POH emergency gear-extension procedure before departure: a check on the ground proves only that the gear is down and indicating down now. Brief the passengers as 91.107 requires: how to fasten and unfasten their seat belts and, where installed, shoulder harnesses, and that they must be fastened for movement on the surface, takeoff and landing. Add the exits and emergency equipment. Confirm the down-and-locked indications in the preflight, and check them again before takeoff per the POH. The run-up is for cycling the propeller and checking the engine instruments; it tells you nothing about how the gear will work in flight.

AFH (FAA-H-8083-3C), Transition to Complex Airplanes; 14 CFR 91.7, 91.107

Brings together: Preflight Assessment · Flight Deck Management · Before Takeoff Check

Teaching this? The instructor lesson plan →

Study aid, not FAA guidance. Sources: Airplane Flying Handbook (FAA-H-8083-3C); Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C); Risk Management Handbook (FAA-H-8083-2A); Commercial Pilot ACS (FAA-S-ACS-7B); Your airplane's POH/AFM; AIM. Checked against current sources 2026-11-13.