TURNS, STEEP TURNS, AND COLLISION AVOIDANCE MANOEUVERING
- TURNS, STEEP TURNS, AND COLLISION AVOIDANCE MANOEUVERING
Students must demonstrate the ability to perform level, descending, or climbing gentle and medium turns, as well as level steep turns using co-ordinated inputs. Develop the skills to safely and effectively change the heading and altitude of the aircraft in a spontaneous fashion for the purpose of avoiding imminent collision.
While gentle and medium turns are not specific flight test items, you must demonstrate overall the ability to conduct these turns in safe and accurate fashion. In contrast, steep turns are a specific flight test item, and you must demonstrate the ability to execute a steep turn through 360°, with an angle of bank of 45°, using a pre-selected and prominent geographic point as a heading reference. The Examiner will specify the airspeed, altitude, and reference point prior to entering the steep turn.
Private Pilot Students must:
- complete appropriate safety lookout before entering the steep turn;
- roll into and out of turns, using smooth and coordinated pitch, bank, yaw and power control
- roll into a coordinated turn with an angle of bank of 45°;
- maintain coordinated flight;
- maintain the selected altitude (±100 feet), airspeed (±10 knots) and angle of bank (±10°);
- maintain an effective lookout;
- visually recover from the turn at the pre-selected recovery reference point (±10°).
Commercial Pilot Students must:
- maintain an effective lookout;
- roll into and out of turns, using smooth and coordinated pitch, bank, yaw and power control;
- maintain the specified altitude (±100 feet) and airspeed (±10 knots);
- maintain the bank angle of 45° (±5°) while in smooth stabilized flight;
- reverse the direction of turn and repeat the manoeuvre in the opposite direction;
- roll out of the turn (at approximately the same rate as used to roll into the turn) at the reversal heading and the entry heading (±10°);
- divide attention appropriately between outside visual references and instrument indications.
There are three types of turns: gentle turns are up to 15° bank, medium turns are between 15 and 30°, and steep turns are in excess of 30°. For the purpose of this exercise, a steep turn is a 45°-bank turn.
Prior to performing a steep turn, the aircraft must be completely stable. So often students rush this, but before you perform a steep turn, establish a power setting that will produce airspeed, say 2300 RPM; then trim the aircraft to maintain the desired altitude, lining the aircraft nose with a prominent geographic feature—if the desired altitude is 3500’, don’t settle for 3480’ or 3540’, but make sure the altimeter is “pegged.” Note the airspeed, because this exercise requires ideally that airspeed remains constant throughout the turn.
Before initiating the turn, check for vicinity traffic on both sides, first in the opposite direction of the turn, and then in the turn direction.1 Now you are all set. Smoothly but firmly initiate the roll in reference to the attitude indicator, but don’t forget the necessary rudder inputs in the direction of the turn to maintain the ball in the middle of the turn co-ordinator. After rolling past 30°, get ready for required back-pressure, because the configuration of wings (with the lift vector moving excessively away from its normally vertical position) will require that input back-pressure to produce a compensating increase in the angle of attack. If you fail to input the backpressure, the aircraft will begin a descent. The timing and magnitude of the backpressure will come with experience and practise, but during the turn intermittently glance at your altimeter and vertical speed indicator for any signs of a descent—then counter the descent by sufficiently increasing the angle of attack. Simultaneously, don’t overdo the backpressure or the aircraft will climb. Now, here is where it gets tricky—as you input backpressure the aircraft will, without correction, decrease speed. How to compensate sufficiently to keep a constant airspeed with the backpressure? Normally, you could drop your nose slightly by pitching forward, but this of course, will cost you altitude (remember the altitude must be kept constant). Instead, you respond by advancing the throttle—usually only 100 or 200 RPM is required, but this of course varies with your gross weight. Practise and experimentation with power is required here. Now, back to the rolling motion. Using your attitude indicator as reference, allow the roll to continue to the 45° marking (make sure you can read the instrument correctly), and then keep it there. Remember that when the ailerons are neutralized, the rudder should be neutralized as well. Further complications arise, however, as this is not an instrument flying manoeuvre; instead, safety requires that you scan the sky during the turn in the direction of rotation. So how do you keep your eyes on the instruments for reference? The answer is that you keep your eyes in the direction of the turn and then periodically scan the instrument panel.2 Say to yourself “look for traffic, look for traffic, cross-check, cross-check, look for traffic, look for traffic, cross-check, cross-check . . .” When you say “look for traffic,” do that, scanning for other aircraft; then when you say “cross-check,” do just that—scan your attitude indicator for 45°, correcting if necessary, then your altimeter, again correcting if necessary, and then your airspeed indicator, correcting if necessary as well.
Some additional hints: once the attitude indicator shows 45° bank, visually transpose this angle on to the angle between the glareshield and the horizon—this allows you to monitor the angle of bank as you scan. Secondly, study the exact position of the nose with respect to the horizon as it travels around 360°—making precise pitch adjustment is a fundamental flying skill. Note that the nose position relative to the horizon will look differently in a left, as opposed to a right, turn. Get to recognize the correct visual clues in both directions. At the end of the manoeuvre, look for your rollout point and time it carefully (using adjusting aileron pressure and corrective rudder pressure). As the wings roll level, bring the power back to its initial setting. As you will see, this is one of the most difficult manoeuvres to fly so practise the skill every time you fly.
During the air instruction on turns, your Instructor will introduce you to collision avoidance manoeuvres. The idea behind collision avoidance manoeuvring is that the direction and altitude of the aircraft be changed as quickly as possible, without placing excessive g-force loading on the airframe. The idea, then, is to be “smooth but aggressive.” It is quicker for the aircraft to change altitude downward, rather than upward (just as birds do), so a collision avoidance manoeuvre should normally entail an immediate closing of the throttle, as well as a simultaneous forward push (pitching forward) on the control column. Since it is normally desired to change the lateral direction of the aircraft (left or right), the manoeuvre should also include roll-inputs. So, as you can see, collision avoidance manoeuvres entail simultaneous power, pitch, and roll inputs—the throttle is immediately closed, as the nose is pitched forward and the aircraft is rolled. Your instructor will likely provide practise using something to the effect of “Simulated traffic 12 o’clock!!” You simply respond with the proper inputs in a smooth, yet aggressive, fashion.
There are some special considerations for commercial students with respect to the switchback 180° steep turns. In particular, note that the actual reverse roll through level flight will require some subtle power changes. While the power setting during a sustained 45°-banked turn requires the addition of approximately 100 RPM from the cruise power setting from which the steep turn was entered, the reverse roll will require a momentary return to the original cruise power setting as level flight is passed, and then an increase in power back to steep-turn power setting as the reverse 45° bank is achieved. All of this implies, of course, that you must also manage pitch with equal care. As you roll for the reversal, you will have to ease up on the backpressure that was held to sustain level flight during the stabilized 45°-banked turn, only to increase the back-pressure once a level attitude is passed and the bank is increased for the reverse turn.
- Because of rapid change in direction, a visual check must be done prior to the manoeuvre in both directions, first in direction opposite to the turn, and then in the direction of the turn.3
- During the turn, eyes should predominantly be looking outside the cockpit in the direction of the turn, monitoring that the airspace remains clear. A pilot who does not watch for traffic is not a safe pilot.
- Avoid letting the nose pitch excessively downward, as a spiral can easily develop if the downward movement is not corrected quickly. If a spiral develops, close the throttle, and level the wings prior to recovering from the dive.
- Be conscious of the fact that stall speed will increase as the angle of bank increases. In a level 60°-banked turn (which usually is permitted only when the aircraft is operated in the utility category), the stall speed will increase 40%. In a 40°-banked level turn, the stall speed will increase 13%.
1 The “both-sides” check preceding a turn is applicable to both 45°-bank steep turns and 30°-bank slow-flight turns (see P. 69), both of which entail a rapid change of direction. In the practise area, this could be dangerous without a thorough traffic check.
2 You should be cautioned, however, about over-dependence on the attitude indicator. As an instrument-rated pilot knows, this instrument affords precise positioning of the aircraft and is thus extremely valuable when instrument flying, but it will easily become a crutch for a VFR pilot as more attention to the attitude indicator means less attention for vicinity traffic. Flight test Examiners look for those who “stare at the instruments” with a lack of situational awareness for other traffic.
3 Students often get confused about the need to conduct a HASEL check prior to a steep turn. This is not the case. A steep turn with an angle of bank up to 45° is considered a normal manoeuvre, and they are quite different from stalls, spins, spirals, and unusual attitude exercises which entail a considerable loss of altitude—with these a HASEL check is required. The steep turn is different from gentle and medium turns in that there is a rapid change in direction, and it is therefore prudent to clear for traffic on both sides of the aircraft prior to beginning the manoeuvre.