There is a saying every pilot should know and memorise:
’Take-off is optional, but landing is mandatory.'
Let’s begin with the basics shall we…
To help ensure the safety of all pilots during flight, and to maintain a steady flow of air traffic, there is a basic rectangular traffic pattern (Fig 1) used by most all airports in real-world aviation.
Unless dictated by ATC, it is customary to make entries into the traffic pattern to the LEFT (otherwise known as Live or Active side) and maintain an airspeed of no more than 200 knots: adjusting accordingly so that s/he is compatible and at a safe distance with any other traffic present. In real-world aviation, traffic pattern altitudes range from 500 ft AGL to 1500 ft AGL (500 ft AGL for low performance aircraft, 1000 ft for medium performance aircraft, and 1500 ft AGL for high performance aircraft) (Fig 2).
|THE BASIC ENTRY TRAFFIC PATTERN|
As you can denote from Fig 3, there are multiple entry approach points from which you can enter the circuit, but for the mere sake of keeping it simple, I will be discussing an entry into the circuit from a 45° entry point on the live side.
Figure 1 - Rectangular Traffic Pattern
Figure 2 - Differing ALT according to A/C type
Figure 3 - Entry into pattern circuit
As you approach the airport for landing and with your nose pointed to the midpoint of the runway you intend to use for landing, you should enter the pattern at a LEFT 45° angle to the downwind leg. ALWAYS BE AWARE OF OTHER TRAFFIC!
Side note: When I was learning to fly, I always told: ’Brandon, 90% of what you should be watching is outside of the plane, not inside of it.’ So ALWAYS be aware of the other traffic around you!
During the downwind leg, you should be flying alongside and parallel (up to 1 mile) to the runway at 1000 feet AGL opposite of your intended landing direction. At this point, you should also be slowing to flap speed and extending your flaps. Before you ask…flap speeds vary for EVERY aircraft.
During the base leg portion, and usually at a 45° angle from the end of the intended landing runway, you should make a turn so that you become perpendicular to the extended centreline, whilst continuing at a gradual rate of descent.
During the final approach leg, you should follow your glidepath and be on the runway centreline. Reduce your airspeed and extend your flaps. Your judgement, precision and descent angle whilst approaching the touchdown point makes this the most important leg of the entire pattern. This is when the saying I mentioned before: ‘Take-off is optional, but landing is mandatory’ plays a vital role in the importance of a safe landing.
|GO AROUND, REMAINING IN PATTERN, OR DEPARTURE|
If a go-around procedure is needed or you decide to remain in pattern, you should commence a 90° turn to the crosswind leg beyond the departure end of the runway within 300 ft of pattern altitude.
If you decide to depart from the traffic pattern, you should continue your departure straight out or exit with a 45° turn to the left (when in a left−hand traffic pattern; to the right when in a right−hand traffic pattern) once you are beyond the departure end of the runway and after reaching pattern altitude.
Why is this important? Because having a familiarity with this basic rectangular traffic pattern, helps to significantly reduce the possibility of accidents and thus resulting in the efficiency of making approaches and departures for both ATC and the pilot.
FLAPS & TRIM ADJUSTMENTS
Now that I’ve covered basic airport entry traffic patterns, go arounds, remaining in pattern and departures, I will briefly explain why you need flaps particularly when on your approach and landing.
|During landings, flap extensions provide several advantages such as:|
- Having a tendency to create a stabilising effect and thus handling characteristics of the plane
- Producing greater lift and lowering your landing speed
- Producing greater drag, allowing for a steeper descent angle without increasing your airspeed
- And ultimately reducing the length of your landing roll.
The timing and the degree to which you deploy your flaps are crucial for a safe approach and landing. Deploying your flaps fully at one single point produces a large lift that in turn require you to significantly change your pitch and increase your power in order to maintain proper control of the aircraft. Instead, you should be extending your flaps in increments, especially during the downwind, base and final approach legs to allow for better control of your aircraft and thus amounting to smaller adjustments of pitch and speed.
Due to changes of aerodynamic forces caused by deployment of your flaps, the combination of reduced power and a slower airspeed, airflow over the wings produce less lift and less downward forces on the horizontal stabiliser and ultimately results in a nose-down tendency. To help compensate for this tendency, you must re-trim the elevator on the final approach for more nose-up (Figs 4 & 5).
Figure 4 - Trim Tab Operation
Figure 5 - Trim Wheel
In order for you to obtain this stabilised approach, you must adjust your glidepath so that the true aiming point and desired touchdown point basically coincide with one another. Once you’re on final approach, you should adjust the pitch attitude and power so that you’re descending directly toward your desired aiming point. If your approach and trim are configured in this manner, you should be set-up for a 'hands off ’ approach.
Note: There is no perfect way to trim an airplane, but using trim is an excellent way to reduce your workload in the cockpit, and make your landings more comfortable.
For you geeks like me, here’s a simpler explanation:
If, at any point, you think your desired aiming point on the runway is not where you think it should be, an adjustment must be made to your glidepath. If your approach becomes too shallow, the runway will appear to shorten and become wider. If your approach is too steep, the runway will appear longer and narrower (Fig 6)
Figure 6 - Proper descent angle view
Why is this important? Consequently, the resulting effects of your precise control of airspeed, altitude, power, trim and flaps: your round out, touchdown and landing roll are all much easier to accomplish.
Now that you have a fundamental understanding of what a stabilised approach should ideally be under normal circumstances, I will cover an environmental cause (namely the wind) that create factors in your decision of which techniques should be utilised to help you make a nice touchdown.
What is a slip? A slip is method used most commonly in situations where you encounter an environmental obstacle (usually wind) that can occur at any point during your approach, landing and departure. A slip can also be used during an emergency situation by creating a means of rapidly reducing your airspeed.
- Technical: A slip is a combination of forward movement and sideward movement, where the lateral axis of the plane is being inclined and the sideward movement is being propelled toward the low end of the axis (Fig 7).
Basic: You’re flying sideways to force a change resulting in the way which wind is striking your plane.
There are two types of slips:
INTENTIONAL: These are deliberate cross-controlling of ailerons and rudder to create positive static directional stability when landing.
UNINTENTIONAL: These are most often the result of uncoordinated rudder control and application.
A wing-low or sideslip approach and landing are often used when landing with a crosswind to maintain the plane aligned with the runway centreline. These approaches and landings are accomplished by lowering your wing a little whilst applying just enough opposite rudder to prevent a turn. The plane’s longitudinal axis remains parallel to the original flightpath, but is no longer flying straight ahead. Conversely, the horizontal component of wing lift forces the plane to also move sideways to the lower wing.
You must first align the plane’s heading with centreline of the runway and be sure to take note of the direction and rate of your drift. If you drift too much oppositely, you need to counter-correct by lowering the upwind wing. The plane is naturally going to want to turn in the direction you lower the wing. To help compensate, you need to simultaneously apply opposite rudder to keep the plane’s longitudinal axis aligned with runway (Fig 8).
Figure 7 - Aerodynamics of sideslip
Figure 8 - Angle of sideslip
These approaches, when executed correctly, are beautiful to watch as you can see above. These are commonly referred to as CRABBED approaches. The crabbed approach method is achieved by establishing and maintaining a heading toward the wind whilst maintaining level wings and nose aligned with the centreline of the runway.
If used through to the round out, you must de-crab the instant before touchdown by applying rudder to align the plane’s longitudinal axis with its forward movement. Should you not de-crab, your primary objective then becomes an issue of preventing any subjection to side loads whilst drifting (Fig 10). Which, as you can imagine, can become extremely hazardous for obvious reasons.
Figure 10 - Crosswind touchdown
Why is all of this important? Because, as you’ve hopefully surmised by now, every step from adjusting your trim, to use of flaps, to deciding which slip to use (or not use), congruently help you to determine your approach and landing technique. And lastly, please remember let us all try not to Dutch Roll…typically your passengers (even though fictitious within Infinite Flight) don’t like it.
As always, I am extremely grateful for your time in reading my tutorial. I sincerely and humbly hope it helped to teach you something new or be a great refresher.