Visual Flight - airplanes

See Visual Flight Rules for a discussion of the regulations pertaining to visual flight.

Visual flight or "Visual Attitude Flyng" is a method of controlling an aircraft where the aircraft attitude is determined by observing outside visual references.

The primary visual reference used is usually the relationship between the aircraft's "nose" or cowling against the natural horizon.

The pilot can maintain or change the airspeed, altitude, and direction of flight (heading) as well as the rate of climb or descent and rate of turn (bank angle) through the use of the aircraft flight controls and aircraft engine controls to adjust the "sight picture". Some reference to flight instruments is usually necessary to determine exact airspeed, altitude, heading, bank angle and rate of climb/descent.

There are 3 components to the aircraft's attitude. They are pitch, roll and yaw.

• Pitch can be seen as the vertical relationship between the nose and horizon. Since the pilot / cockpit and nose of the aircraft are all moving together, the pitch attitude is actually seen as the ratio of visible sky to ground. The exact ratio of sky to ground will vary from one aircraft type to another. In a typical light aircraft, the ratio might be 2/3 ground and 1/3 sky when the aircraft is in the cruise attitude
  • Increasing the pitch attitude (nose up) (more sky than ground visible)
    • Airspeed will decrease
    • Altitude will increase
    • Rate of climb will increase (or rate of descent will decrease)
    • Load Factor will increase
  • Decreasing the pitch attitude (nose down) (more ground than sky visible)
    • Airspeed will increase
    • Altitude will decrease
    • Rate of descent will increase (or rate of climb will decrease)
    • Load Factor will decrease

• Roll or bank can be seen as how much the cowling or nose "tilts" to the left or right. The tilt or bank angle usually ranges from 0 to about 30 degrees. Bank angles up to 80 degrees are used in military fighter jets. Glider pilots will commonly use bank angles of up to 45 to 60 degrees.
  • Changing the bank attitude directly affects :
    • Bank Angle
    • Rate of Turn
    • Load factor
  • When the bank angle increases past about 25-30 degrees, secondary effects oocur :
    • Airspeed - will decrease as the bank angle is increased
    • Pitch attitude - will decrease (nose down) as a result of the decreasing airpspeed
    • Altitude - will decrease as a result of the decreased (nose down) pitch attitude
  • If a constant altitude / constant airspeed turn is desired, the pilot compensates for the secondary effects by :
    • increasing the power setting - to maintain airspeed
    • increasing the back pressure in order to maintain the(pitch attitude] and therefore the 'altitude

• Yaw refers to the direction in which the nose of the aircraft is pointing. It is seen as a horizontal movement of the nose across the horizon. It is possible for the nose of the aircraft to be pointing in a direction different than which the aircraft is moving !

Depending on the aircraft type, the sight picture will vary, but in general the principles are the same regardless of type. For example, if a pilot's sight is completely filled with ground, with no sky visible, this would indicate an extremely nose-down attitude and a corresponding rapid rate of descent. An obvious exception would be in a mountainous region, which in this case could indicate the aircraft is in level cruise flight, but possibly in danger of impacting the terrain ! If the pilot can see only sky, a nose-high attitude is indicated. In either of these cases, the horizon would not be visible, and would be one of the first indications that the aircraft is in an unusual flight attitude.

Cruise attitude

An aircraft is usually designed so that the "horizon/nose sight picture" that the pilot sees in cruising flight is similar to that seen when the aircraft is on the ground. This will also usually coincide with having the interior floor and passenger compartment in a level attitude. In cruise flight, the aircraft maintains a constant airspeed and altitude, which is the result of a constant pitch attitude and aircraft power setting. A particular aircraft will have a design cruise airspeed at which the plane will be in an essentially level attitude.

When a pilot is undergoing flight training, the cruise attitude is usually one of the first things that they will learn. The sight picture associated with cruise flight, will include the horizon and a combination of sky and ground.

Climb attitude

To make an aircraft climb, i.e. gain altitude, the pilot will raise the nose higher than it is in the cruise attitude. For many light aircraft, this will correspond to a sight picture where the aircraft nose appears to be on or just slightly above the horizon. The amount of movment will typically not exceed 10-15 degrees.

If the pilot does not adjust the engine power by increasing the throttle setting, the aircraft's airspeed will decrease. The amount of decrease will depend on the amount the nose was raised compared to the cruise attitude, and what the power setting is. When flying light aircraft, power is usually increased to full for any extended climb.

Even if power is increased, the airspeed will still decrease if the pitch attitude is increased beyond a certain point. The amount that the airpseed decreases with increasing pitch attitude (nose up) is aircraft type dependent, and is usually directly related to how much excess power is available and the power setting used.

• Types of Climbs

• The pilot controls the rate of climb, and the airspeed during the climb by the combination of the pitch attitude and power setting. He will choose the pitch-power settings according to the amount of altitude gain required or how quickly it is desired to climb, or if a constant airspeed is desired. Every aircraft type has limits on the pitch-power settings that can be used for climbing flight. Typically it is the pitch attitude which is the more limiting factor. Somewhat like an automobile, if the "slope" is made too steep, by an excesive increase (nose up) in pitch-attitude, the aircraft will lack sufficient power to climb, and in an extreme nose-up attitude, the airspeed may decrease to the point where the aircraft will stall. (Some aircraft have a duration limit for a particular power setting)

• There are 3 common types of climb :
  • Cruise
    • This is usually used after takeoff when the aircraft has reached a safe height and there is no further urgency to climb. The objective is to combine an adequate climb rate with maximum forward speed. The airspeed will typically be around eighty to ninety percent of cruise speed for a light aircraft.
  • Max Rate
    • The objective is to climb at the greatest rate of altitude gain per distance covered over the ground. It is referred to as Vy. Airspeed is typically about double the stall speed for a light aircraft.
  • Max Angle
    • The objective is to climb with the greatest gain of altitude per unit of time. It is referred to as Vx. Typical airspeeds are usually 150% of stall speed.
  • A fourth type of climb might be termed a zoom climb. It is typically used when only a slight amount of altitude gain is requred (100 ft or less). For this type of climb, the pilot simply increases the pitch attitude (nose up) momentarily without adjusting the power setting, accepting a temporary loss in airspeed.

• In light aircraft, full power is typically used when climbing. The type of climb is therefore determined by the pitch attitude. The aircraft's Pilot Operating Handbook (P.O.H.) will list the airspeeds for the various types of climbs. The pilot adjusts the aircraft's pitch attitude to match the speed quoted in the P.O.H. for that particular type of climb desired. While the airspeed indicator (ASI) is used for precise airspeed control, it is generally fairly easy for an experienced pilot to distinguish the different "look" of the cruise,max-rate, or max-angle climb attitudes when he is familiar with a particular aircraft type. Larger aircraft follow the same principles, the only difference being that full power is not always used, especially at lower altitudes, as the engines are usually powerful enough to create excessive airspeed or engine overheating.

Descent attitude

To make an aircraft descend, i.e. lose altitude, the pilot will lower the nose lower than it was in the cruise attitude. For many light aircraft, this will correspond to a sight picture where the aircraft nose appears to be slightly below the horizon. The actual amount of down movement usually will not exceed about 10 degrees for most normal descents.

If the pilot does not adjust the engine power by decreasing the throttle setting, the aircraft's airspeed will increase. The amount of increase will depend on how much the nose was lowered compared to the cruise attitude, and what the previous power setting was. When flying [light aircraft], power usually is decreased to around 2/3 full for a cruise descent.

Even if power is decreased, the airspeed will still increase if the pitch attitude is decreased (nose down) beyond a certain point. The amount that the airpseed increases with decreasing pitch attitude '(nose down)' is type dependent, and is usually drectly related to how aerodynamically clean the aircraft is. If the airspeed is allowed to increase to or past Vne structural damage can occur.

Takeoff attitude

The takeoff attitude is similar to and for some aircraft, identical to a cruise climb attitude.

Landing attitude

The landing attitude has 3 actual "sub attitudes" :

• Descent
  • The descent during the final leg is typically flown at 1.3 times the stall speed of the aircraft, and usually with the flaps extended. Large "airline" (transport) type aircraft, are flown on a 3 degree slope or glidepath. Smaller light aircraft will typically be flown on a 4 to 6 degree glidepath. Typical power settings are 3/4 full power. The rate of descent typically ranges from approximately 300 feet per minute for light aircraft to 700 f.p.m. for transport category.
• Roundout
  • Contacting the runway with a 300 f.p.m. descent rate will be extremely uncomfortable and can cause damage to both the aircraft and passengers. For that reason, the aircraft will be put into a roundout attitude shortly before it would otherwise contact the ground. The attitude is similar to the cruise attitude and is accomplished by the pilot increasing the pitch attitude (raising the nose) at approximately ten to fifty feet above the ground, depending on the aircraft type. Larger, heaviver aircraft will be put into the roundout attitude at higher heights than smaller lighter aircraft.
• Flare
  • The final attitude is the flare which is basically a continuation of the roundout attitude to a slight climb attitude. The objective is to descend at the minimum descent rate and lowest possible forward speed. When performed correctly the aircraft will gently contact the ground at a descent rate of 100 f.p.m. or less