The Price of Safety

What price would you be willing to spend to ensure the safety of your friends, family, and yourself? $100? 1000? 10,000? I am often surprised at some of the actions taken by pilots in order to save a few dollars.

One area in particular I am passionate about promoting is the fitment of stall warning or angle of attack devices. In an environment where loss of control events are the number one cause of fatal accident world-wide, I believe all aircraft owners should consider the fitment of a device to warn pilots of an impending stall!

Whilst training for stall recognition and avoidance and familiarising yourself with your aircraft stall characteristics must always be the primary barrier to protect against encountering a stall in flight, a stall warning device may just act as a final barrier to safety, and better yet - They may not be as expensive as you think!

Let’s take a quick look at a few different types of stall warning device available to aircraft owners:

Vane-type stall warning device

No doubt you have seen aircraft fitted with a small tab on the leading edge of the wing. This type of stall warning device uses a small tab, or vane, to detect change of the stagnation point on the wing. When an aircraft airspeed decreases, the angle of attack increases and the stagnation point moves aft. This change in stagnation point activates an electric switch which engages an aural alert to notify the pilot of an impending stall.

Reed-type stall warning device

If you have ever flown a Cessna, you will likely recall the unmistakable screeching of the stall warning during landing. This is the sound of a reed-type stall warning device. This type of stall warning device is a small slot on the leading edge of the wing. As the angle of attack increases the reed (much like that in a musical instrument) sounds, alerting the pilot of a stall.

Stall Strips

Have you ever noticed wedge-shaped strips fitted to the leading edge of an aircraft wing? Stall strips may be fitted to an aircraft and offer two advantages. Firstly when a stall does occur, stall

strips create a more controlled stall across the wing. In addition to this, they also increase wing buffeting before a full stall, alterting the pilot that a stall is about to occur. Stall strips may be used in addition to an aural stall warning device.

Angle of attack devices

Angle of attack devices, as the name suggests, displays the aircraft’s angle of attack. These devices may be displayed on a visual display and/or an aural alert. Most commonly used on commerical and military aircraft, angle of attack devices can alert pilots prior to encountering a stall. Whilst these devices historically were much more expensive than other stall warning options available, many modern avionics systems may permit the display of angle of attack information or have the ability to have this information added.

More recently, devices have become available to display angle of attack without the need for the installation of addional probes on the aircraft, known as probeless angle of attack devices. One such device is the uAvionix AV-20S and AV-30 which only requires inputs from the pitot-static ports and provide a range of additional features such as attitude, slip/skid and G-meter whilst offering aural angle of attack alarms to warn the pilot of a stall.

Does your aircraft have a stall warning device fitted? If not, what price are you willing to put on safety?

RAAus recommends aircraft owners contact their aircraft manufacturer or local representative to discuss the possibility of fitting a stall warning device to your aircraft. Differing requirements apply depending on your aircraft type and certification.

Fitment of stall warning devices in some cases may result in noncompliance and if not fitted correctly, may negatively impact safety.

too close for comfort!

In the first half of 2021, RAAus had 16 occurrences relating to near miss or loss of separation between aircraft, many of which resulted in one or both aircraft taking immediate action to avoid a collision. So how is it that in the modern of technology, with the use of radios and other collision avoidance technology, that near miss events continue to be one of the most common occurrence types? Well, of course, these events come down to human factors: The pilot!

The most common similarity in near collision events is that they most regularly occur within the circuit.

What can you do to avoid a near miss? There are a number of contributing factors that often lead to a near miss occurrence including high workload, poor look-out or radio calls, distraction, and non-standard circuit joining procedures.

All of these factors are standard barriers that work together to maintain traffic separation, however, when the holes in the Swiss cheese start to align and multiple barriers fail, the outcome may result in two aircraft passing close by one another, or in the worst case scenario, a mid-air collision.

The following are top recommendations for avoiding a near miss occurrence: 1. Correct radio procedures Correct radio procedures is the most effective tool for traffic awareness, however, this does rely on other traffic being fitted with a radio that is in use, tuned to the correct frequency and requires pilots to be actively listening to calls.

CAR 166C requires pilots of aircraft carrying a serviceable radio which they are qualified to use, to make a broadcast whenever it is reasonably necessary to do so to avoid a collision, or the risk of a collision, with another aircraft at a non-controlled aerodrome. Radio carriage is mandatory for aircraft operating at or within the vicinity of a registered or certified aerodrome and for aircraft operating above 5000ft AMSL in class G airspace. Remember, ‘in the vicinity’ is within 10 nm, and at a height where your operations could be in the way of other traffic.

When operating outside the vicinity of an aerodrome, pilots should monitor the appropriate Area VHF frequency.

Radio broadcasts must include: (a) the name of the aerodrome; (b) the aircraft’s type and call sign; (c) the position of the aircraft and the pilot’s intentions.

The following table provides recommended broadcasts in the vicinity of non-controlled aerodromes:

(Image source: https://www.atsb.gov.au/media/5779431/figure-4.png)

Pilots should ensure procedures are in place to confirm they are operating on the correct frequency prior to flight or when operating within the vicinity of an aerodrome. In addition to this, pilots should actively monitor radio calls in order to build a mental picture of what other traffic is operating within the local area including their location and intentions. This is particularly important where traffic on the local frequency may include aircraft operating at multiple airfields. If you miss a radio call, or are not sure where someone may be located, always ask for other traffic to “say again” in order to ensure traffic is not missed. Near miss occurrences often occur due to pilots not making radio calls as they believe they are the only aircraft operating within the vicinity of the airfield, for this reason, radio calls should be made even if you believe there is no other traffic in the local area.

2. Correct circuit joining procedures A common cause of near miss occurrences is failure by a pilot to conduct normal circuit joining procedures. In many cases pilots are surprised to find an aircraft join the circuit for the reciprocal runway to that of which other aircraft are already established.

Whenever possible pilots should elect to join overhead. Not only does this allow for the pilot to establish the wind direction, but also allows pilots to visually identify other aircraft established within the circuit. Particular care should be taken to avoid complacency when operating at your home airfield. In many cases, pilots choose to join downwind or for a straight in approach and fail to identify other traffic established within the circuit.

3. Lookout, lookout, lookout During VFR flight our eyes should remain outside the cockpit at least 70% of the time, however in a changing world full of additional avionics, GPS devices and electronic flight bags (EFBs), we have an increased number of distractions leaving our eyes inside the cockpit more than ever before.

Despite improvements in radios, GPS and traffic information, it is still just as important, if not more important, that we fight the urge to rely on our devices and turn our eyes outwards. Prior to entering the vicinity of an aerodrome, or when established within the circuit, pilots should close their ipads and avoid other distractions in an attempt to visually identify any traffic you have heard, or may not have heard, operating in the area.

Of course our ability to identify other aircraft is only as good as our scanning technique. The human eye requires 1-2 seconds once stationary in order to focus. When conducting a visual scan of the horizon our eyes are unable to focus if one continuous sweep is made. It is therefore important that pilots divide the sky up into 10 to 15 degree blocks, stopping to allow the eyes to focus within each block.

4. Planning Pilots must ensure they have completed thorough flight planning prior to each and every flight. This is particularly important when operating cross country, or at an unfamiliar airfield.

Pilots should take note of any airfields along their planned route in order to avoid inadvertently transiting through an area on the incorrect frequency with the potential to conflict with circuit traffic at an aerodrome.

Whilst en-route, or prior to entering the vicinity of an airfield, pilots should have pre-briefed their arrival and familiarised themselves with local procedures. This means that the pilot can focus on identifying other traffic and maintaining an active lookout rather than reviewing local charts when joining the circuit. Cross country flights must be conducted using the appropriate hemispherical cruising levels to avoid potential conflict with opposite direction traffic in flight.

As pilots, we are all guilty of allowing complacency to cloud our flying operations, however with near miss occurrences occurring all too regularly, pilots should revise their operating procedures in order to go back to basics, and help avoid near miss occurrence!

(Image source: https://vfrg.casa.gov.au/operations/cruising-levelrequirements/prohibited-restricted-and-danger-areas/)