2.03 - Four Fundamentals

Straight Level Flight

  • Definition: straight level flight means maintaining a constant heading and altitude.

  • It is not hands-off: pilots must make small corrections for deviations caused by bumpy air, wind changes, and unintentional turns, climbs, and descents.

  • Pilot focus and horizon scanning:

    • FAA guidance: keep the outside horizon in view 90% of the time and look inside the cockpit only 10% of the time to check instruments.

  • Pitch attitude and horizon reference:

    • Level flight pitch is assessed by comparing the aircraft’s nose with the horizon.

    • If the plane starts to climb, the pitch attitude is too high and should be lowered.

    • If losing altitude, the pitch attitude is too low and should be raised.

  • Maintaining a constant heading (lateral level):

    • Look outside and compare the wings against the horizon; both wingtips should be at the same distance above or below the horizon.

    • If one wing is higher, the airplane is turning.

  • Lift, weight, and flight controls in straight level flight:

    • Both airspeed and angle of attack control lift; in straight level flight the throttle is primarily used to maintain the desired airspeed, and the elevator is used to control altitude.

    • The pitch required for level flight is not fixed: lift increases with airspeed, so the slower you are flying, the more you must pitch up to maintain altitude.

  • Cruise flight relationship (thrust and drag):

    • In normal cruise flight with constant airspeed, thrust equals drag: T = D.

    • If the pilot increases engine output (throttle), thrust increases and accelerates the aircraft because thrust exceeds drag.

    • As speed increases, drag also increases until drag equals thrust and the aircraft stabilizes at the new cruise airspeed.

  • Slowing down in level flight:

    • To slow down, reduce throttle, increasing the relative effect of drag and causing deceleration.

    • While slowing, the pilot must smoothly and continuously pitch up to maintain altitude as airspeed decreases.

    • As the aircraft slows, drag changes (in the transcript: "the amount of drag created will also decrease" with slowing in this context—note: in standard aerodynamics, induced drag typically rises at lower speeds, but the transcript states this decrease and it is reflected here).

    • Eventually, drag again equals thrust and a steady airspeed is maintained.

  • Transition to climb or descent from level flight:

    • To climb, create more lift than weight (L > W) by pitching up and applying power.

    • Entering a climb changes the flight path from level to climb attitude.

Climb (Three types and key concepts)

  • In a climb, weight acts straight down but is not perpendicular to the flight path, creating a rearward component that increases total drag.

  • To balance the forces and continue climbing, additional thrust is required.

  • Three climb profiles (types) with different power settings and pitch attitudes:

    • Best rate of climb (V_Y): maximizes altitude gain per unit time (maximum feet per minute).

    • Best angle of climb (V_X): maximizes altitude gain per unit horizontal distance (steepest climb path).

    • Note: VX climbs steeper but reaches the target speed more slowly than VY.

  • Returning to straight level flight from a climb:

    • Initiate the level-off at approximately 10% of the rate of climb. For example, if climbing at 500 ft/min, aim to level off at about 10% of that rate (roughly 50 ft/min), then adjust as needed to reach cruise speed.

  • Transition to cruise: once the aircraft reaches the desired cruise airspeed, reduce power to cruise setting.

Descent (Types and guidance)

  • In descent, the forward component of weight adds to thrust requirements differently than in climb.

  • Three types of descents:

    • Partial power descents (cruise descents or en route descents): normal method to descend.

    • Target descent rate for this method: about 500\ ext{ft/min}.

    • Descents performed with pitch adjusted to maintain the desired airspeed; throttle controls descent rate.

    • Descent at minimum safe airspeeds: steeper descents used during approach to landing on short runways.

    • These steep descents are flown at very low airspeed with a narrow margin for error; the risk of stalling is higher.

    • If stall onset is felt, large amounts of power may be needed to accelerate out of the stall tendency.

Glide (basic controlled descent without power)

  • Glide is a basic maneuver in which the airplane loses altitude in a controlled descent with little or no engine power.

  • Forward motion is maintained by the forward component of weight.

  • Gliders (which have no engine) routinely use this, and other aircraft use glide during engine-out situations or for landing procedures.

  • Gliding distance is maximized by maintaining the minimum drag airspeed.

  • Glide is described as a fundamental maneuver that pilots should master.

Turn mechanics (banking, control coordination, and rollout)

  • A turn is initiated by banking the wings toward the desired turn direction.

  • Although it can seem like a roll is controlled only with ailerons, multiple controls are involved:

    • In a left turn example, banking is achieved with the ailerons; the right wing’s aileron moves up (or relative deflection) to increase lift on the right wing, initiating the bank toward the left.

  • Effect of bank on lift and weight:

    • In straight and level flight, 100% of the lift is used to counteract weight (vertical lift).

    • In a bank, lift is tilted toward the bank direction; part of the lift goes horizontally, producing the turn. The vertical component of lift still opposes weight, but less lift contributes to supporting weight directly.

    • Result: there is a horizontal component of lift that causes the turn, and less vertical lift available to hold altitude unless lift is increased.

  • Need to maintain altitude during a turn:

    • Because some lift is redirected from vertical to horizontal, pilots must increase total lift by slightly pitching up a few degrees while maintaining the bank.

  • Drag implications during a turn:

    • The banked wing producing more lift also produces more drag, particularly on the wing producing more lift (the right wing in a left turn example).

  • Adverse yaw: the tendency for the nose to yaw opposite the turn direction due to differential drag causing the airplane to yaw away from the desired turn.

    • Counteract adverse yaw with rudder in the direction of the turn (e.g., press the left rudder pedal for a left turn).

  • Coordination of inputs: during a turn, pilots use all three primary flight controls together—ailerons, rudder, and elevator.

  • Bank angle and input amounts: different bank angles require different amounts of control input; practice makes this more intuitive.

  • Rollout to level flight:

    • As the aircraft rolls back toward level, pilots must lead the rollout before arriving at the target heading because the airplane will continue turning while the wings remain banked.

    • General rule: lead the rollout by about one half of the amount of banked angle (i.e., roll out slightly earlier to establish straight-and-level flight on the desired heading).

Key concepts and relationships (summary of essential ideas from the transcript)

  • Fundamental forces and their roles:

    • Lift (L) counteracts Weight (W).

    • Thrust (T) minus Drag (D) determines airspeed and acceleration.

    • In level flight: L \approx W\; \text{and}\; T \approx D.

  • Level flight control emphasis:

    • Pitch controls altitude, throttle controls airspeed.

    • Lift increases with airspeed; slower speeds require more pitch to maintain altitude.

  • Banked flight (turns) physics:

    • Lift vector tilts with bank angle; vertical component must still offset weight to hold altitude if desired.

    • Horizontal lift component provides centripetal force for turning.

    • Adverse yaw is an important consideration; counter with rudder in the turn direction.

    • Rollouts require anticipation to re-establish straight-and-level flight.

  • Climb and descent dynamics:

    • Climb requires more thrust and lift; weight acts downward and contributes to increased drag in a banked climb.

    • VY (best rate of climb) vs VX (best angle of climb) describe two common climb profiles.

    • Level-off during climb uses a 10% rule relative to the rate of climb to transition to cruise.

    • Descent strategies include partial power descents (target ~500\ \text{ft/min}), and minimum safe airspeed descents for approaches, each with different pitch and power settings.

  • Glide distance optimization:

    • Maintain minimum drag airspeed to maximize gliding distance; glide is a fundamental skill, particularly during engine-out scenarios.

Practical implications and situational awareness guidance

  • Regular outside-the-cockpit scanning is emphasized to maintain situational awareness and horizon reference.

  • Smooth transitions between maneuvers require coordinated use of all primary flight controls (ailerons, elevator, rudder) and appropriate throttle management.

  • Understanding climb/descent profiles helps manage fuel efficiency, obstacle clearance, and safe operation during all phases of flight.

  • Ethical/practical emphasis: maintain horizon-focused scanning, proper control coordination, and anticipation of the aircraft’s response to control inputs to ensure safe flight operations.

Notation and selected formulas to remember

  • Level flight relationships:

    • Lift and weight balance: L \approx W

    • Thrust and drag balance in cruise: T = D

  • Banked flight (turns) geometry:

    • Lifting force direction shifts with bank angle (\phi): vertical component L\cos\phi supports weight, horizontal component L\sin\phi provides centripetal force for turning.

  • Climb profiles:

    • Best rate of climb: V_Y

    • Best angle of climb: V_X

  • Descent rate target (partial power descent): \dot{h} \approx -500\ \mathrm{ft/min}

  • Altitude tracking during level-off: level off at approximately 0.10 \cdot \dot{h}_{\text{climb}}

  • Altitude reference for glide: maximize gliding distance by selecting the minimum-drag airspeed, i.e., the airspeed corresponding to the lowest total drag.