CASA's CAAP 155-1, Aerobatics, is an excellent resource for aerobatic pilots having a very broad and informative content.
Some extracts from the CAAP are provided below and you can also download the CAAP.
2.4 Basic aerobatic manoeuvres
The types and combinations of aerobatic manoeuvres are virtually unlimited, but the basic aerobatic manoeuvres specified in CAO Section 40.0 for the issue of an aerobatic endorsement are:
- Barrel roll
- Slow roll
- Roll of the top
- Stall turn
- Spinning - which is listed as a separate endorsement in CAO 40.0 but is a pre-requisite for the issue of an aerobatic endorsement and can also be considered as a basic aerobatic manoeuvre.
3.11 Flight Manual Manoeuvre Limitations
3.11.1 In utility category aeroplanes, the manoeuvres that can be performed safely are listed in the approved aircraft flight manual and/or on placards located in the cockpit.
3.11.2 Acrobatic category aeroplanes are normally suitable for most standard aerobatic manoeuvres but some types may have certain restrictions. The aircraft's flight manual or cockpit placards will normally specify any manoeuvres that are not permitted or any other restrictions on aerobatic flight.
3.12 Airspeed Limitations
3.12.1 The aircraft flight manual will specify airspeed limitations for the aircraft. Limitations that are particularly relevant in aerobatics are:
- VNE - never exceed speed
- VNO - normal operating limit speed
- VA - maximum manoeuvring indicated air speed (IAS)
- Entry speeds for manoeuvres
- Maximum flick manoeuvre IAS
3.13 Manoeuvring Speed
3.13.1 Manoeuvring speed (VA) is the speed above which full deflection of the elevator control will exceed aircraft structural limitations. Below VA the aircraft will stall before structural limits can be exceeded. VA will be specified in the aircraft's flight manual and placarded on the instrument panel. Full control deflection of any flight control should be avoided above this speed.
3.13.2 It is important to note that VA is established at the aircraft's maximum all-up weight or maximum aerobatic weight, and that at lighter weights it is possible to exceed G limitations at speeds less than the specified VA.
3.13.3 It could be argued that exceeding G limitations at a lighter weight may not necessarily overstress the wing structure because the lift forces imposed at the lighter weight for the same G are proportionately less, and therefore the wing structure should be strong enough to withstand the load. However, other airframe components such as engine mountings, attachments and other equipment still experience the full G loading and these structural components could fail even though the wing does not.
3.13.4 Thus, to stay within a safe operating envelope, the pilot should manoeuvre near VA with caution, monitor the accelerometer rather than rely solely on airspeed limitations, respect rolling G and flick roll limits, and be cautious in the use of abrupt control inputs.
5.1 Civil Aviation Regulation (CAR) 155
5.1.1 CAR 155 specifies rules limiting the conduct of aerobatic flight. Aerobatics pilots should be familiar with all the provisions of CAR 155 and the following provides a summary of the main elements of the regulation:
- Aerobatics must only be conducted in visual meteorological conditions (VMC) by day.
- A pilot must not perform aerobatics in aircraft unless the Certificate of Airworthiness (COA) or flight manual for the aircraft specifies that the aircraft can perform aerobatics.
- Straight and steady stalls or turns with not more than 60o bank, are not classified as aerobatics.
- Aerobatics must not be conducted below 3000' above terrain or objects on the ground without the written permission of CASA.
- Aerobatics are not permitted over populous areas or public gatherings without the written permission of CASA.
- Before conducting aerobatics, pilots must ensure that:
- There are no loose articles in the aircraft
- All locker and compartment doors are fastened
- Safety harnesses on vacant seats are secured so as not to foul controls
- Dual controls are removed or passengers are briefed not to interfere with the controls and there is adequate communication with the pilot. (See Civil Aviation Regulation (CAR) 226 and Civil Aviation Order (CAO) Section 20.16.3)
- All occupants are secured with correctly adjusted safety harnesses.
6.2 Spin Endorsements
6.2.1 The training and the issue of a spinning endorsement may only be conducted by a flight instructor who holds a spin training endorsement. When entered in a pilot's logbook, the spinning endorsement specifies the type of aeroplane in which competency was demonstrated, but is valid for any other aeroplane approved for spinning.
6.2.2 Separate endorsements are required for upright and inverted spins.
6.3 Aerobatics Endorsements
6.3.1 To be authorised to conduct aerobatics as pilot-in-command, a pilot must hold a logbook endorsement for upright spins and a logbook endorsement for the aerobatic manoeuvres to be performed.
6.3.2 An aerobatic endorsement must be made in the pilot's logbook by either a flight instructor or an approved person and must include the manoeuvres that the pilot is authorised to perform. The following manoeuvres are specified in CAO Section 40.0, as needing specific authorisation:
- Barrel roll
- Slow roll
- Roll of the top
- Stall turn
6.3.3 A pilot may perform any combinations of the manoeuvres endorsed and needs no further endorsement to perform other manoeuvres not listed in the Order.
6.3.4 Aerobatic endorsements entitle a pilot to conduct aerobatics in accordance with CAR 155, not below 3000' above ground level (AGL).
To perform aerobatics at lower levels, a separate low-level aerobatics permission issued by CASA under CAR 155 is required.
6.5 Aerobatic Training Endorsements
6.5.1 Flight instructors must be certified as competent to give instruction in spins and in aerobatics and have the logbook endorsements specified in CAO Section 40.1.7 to that effect. An instructor must hold a spin training endorsement and a training endorsement for each the aerobatic manoeuvres which require endorsement under CAO Section 40.0 and for which he or she gives instruction. Aerobatics training endorsements must be entered in the instructor's logbook by either a chief flying instructor (CFI) or a Grade 1 instructor who also must hold the training endorsement.
6.5.2 Assessment of competence for the issue of an aerobatic training endorsement should be on the basis of the instructor's ability to give ground and flight instruction and assess competence in each of the units and elements listed in the aerobatics competency standards in Appendix A of this CAAP. Sample Achievement records for issuing instructor training endorsements are included in Appendix B of this CAAP.
6.5.3 The forms of log-book endorsement for spinning, aerobatic manoeuvres and aerobatic instruction are specified in CAO Section 40.1.7, Appendix III.
6.7 Low Level Aerobatic Training
6.7.1 Instructors or approved persons authorised to give aerobatics instruction, who also hold a low-level aerobatics permission, may give aerobatics instruction down to the limit specified in the permission.
6.8 Requirement for Air Operator's Certificate (AOC)
6.8.1 Aerobatic flight instruction is given for the purpose of increasing a pilot's skill and is therefore classed as flying training. Aerobatic training for the issue of an endorsement or permission must be conducted under an Air Operator's Certificate (AOC) and be specified in the holder's Operations Manual. Note: This does not prevent a person who already holds an aerobatic endorsement or permission from practising aerobatics as a private operation to maintain or improve their own skills.
6.8.2 Therefore, an initial aerobatics endorsement can only be given by a suitably qualified flight instructor or approved person operating under a flying school AOC. Subsequent aerobatics activities such as advanced aerobatics and low-level aerobatic permissions may be given by pilots approved by CASA.
7.12 Situation Awareness
7.12.1 Situation awareness is the awareness of all the elements in the environment, how they affect your flight, and how they could affect it in the future. Situation awareness requires good anticipation and asking 'what if'? Considering all possibilities and planning operations to proactively identify and manage the potential threats and errors for each flight will aid in enhancing situational awareness. Typical issues to consider for aerobatics activities are:
- Pilot fitness
- Pilot G awareness and readiness
- Aircraft airworthiness
- Aircraft G loading and manoeuvre limitations
- Aircraft airspeed and engine limitations
- Manoeuvre entry parameters
- Unusual attitude/ spin recognition and recovery
- Density altitude effect on performance
- Area/ terrain/ ground features
- Height limitations
- Cloud base and visibility
- Airspace requirements and other traffic
- Use of clearing manoeuvres
- Extraneous pressures
- Possible effects on persons, animals and property on the ground
7.16 Recognition And Recovery From Mis-handled Manoeuvres
7.16.1 In aerobatic flight, there is always the possibility of unintentional entry into a spin or disorienting unusual attitude, and the application of an incorrect recovery procedure is likely to exacerbate the problem.
7.16.2 It is beyond the scope of this CAAP to provide detailed procedures for recovery from all situations in all types of aircraft, but pilots need to be able to recognise and take appropriate recovery action applicable to the aircraft type for each of the following:
- Extreme unusual attitudes, upright or inverted, nose high or low
- Upright spin
- Inverted spin; and
- Spiral dive
7.17 Unusual Attitude Recovery
7.17.3 The following procedure does not require immediate recognition of the aircraft's attitude, but depends on the pilot recognising when the nose has fallen below the horizon and regaining orientation from that reference. It is applicable to both high and low nose attitudes but a low nose attitude will require the following actions to be completed promptly:
- Close throttle
- Centralise and hold controls firmly
- As soon as the nose falls below horizon
- Prevent yaw with rudder
- Roll aircraft upright, wings level with the horizon; and
- Return the nose to level attitude, observing airspeed, G and engine limitations
7.18 Spin Recovery
7.18.1 Modern aerobatic aircraft designs normally have predictable spin characteristics and respond to the standard spin recovery technique. However, older aircraft and non-certificated or amateur built aircraft may have special characteristics which require particular recovery procedures. Therefore pilots need to be familiar with, and practised in, the spin recovery procedure specified for the particular aircraft type.
7.18.2 The following standard spin recovery procedure is applicable, with variations, to most aircraft types.
7.19 Spin Recognition
7.19.1 It is important to determine if the aircraft is in a spin before applying the spin recovery procedure. The two elements which conform that the aircraft is in a spin are:
- Continuous rotation in yaw and roll
- Airspeed is stable (not increasing)
7.20 Upright Or Inverted
7.20.1 When a spin is entered unintentionally from an aerobatic manoeuvre, it is important to establish if the spin is upright or inverted.
7.20.2 Generally, when looking out the front of the aircraft, the sky appears to be above in an upright spin. In an inverted spin the ground appears to be above. In an inverted spin, there will be -G forces tending to lift the pilot off the seat.
7.21 Direction Of Rotation
7.21.1 The direction of rotation may be determined by looking down the nose of the aircraft and confirming the direction of yaw in relation to the ground. The direction of yaw is the direction of rotation of the spin. The direction of spin may be confirmed from the turn needle or the turn coordinator. However, a turn coordinator indication may not always be reliable, particularly if the aircraft is inverted.
7.21.2 Aircraft flight manuals will specify the particular spin recovery procedure for the aircraft type, based on the aircraft's demonstrated handling characteristics during flight testing. It is imperative to know and apply the procedure specified in the aircraft's flight manual or Pilot Operating Handbook for the aircraft type.
7.21.3 The following generalised spin recovery procedure should be applicable in most situations and aircraft, but the procedure specified in the aircraft's flight manual is the ultimate authority.
7.22 Standard Spin Recovery:
- Close throttle
- Centralise ailerons
- Identify if the aircraft is spinning, the direction, and whether upright or inverted
- Full rudder opposite to rotation (opposite to yaw)
- Elevator forward for upright and back for inverted as required to unstall
- When rotation stops, centralise rudder
- Roll wings level and recover to level flight.
7.23 Aircraft Type Differences
7.23.1 Spin recovery procedures will vary between aircraft types and situations. The aircraft flight manual should be the final authority for spin recovery procedure, but some issues that may need to be considered are:
- Too much or too rapid an application of elevator control may blanket the airflow over the rudder, making it ineffective
- Too much or too rapid an application of elevator control may flick the aircraft from an upright to an inverted spin or viceversa
- Use of aileron into the spin may sometimes assist in recovery
- Where there is difficulty differentiating between an upright and an inverted spin, full back control column may ensure the aircraft enters an upright spin.
7.28.1 While recent experience is important in maintaining proficiency, independent opinion on performance is an equally valuable tool for enhancing safety. Because of the high level of skill and the fine safety margins involved in low-level aerobatics, it is strongly suggested that low-level permission holders should undertake a peer review of their performance on a regular basis. An appropriate frequency would ensure that a peer review had been completed within the 15 months previous to conducting any low-level aerobatics.
7.28.2 The peer review process is intended to provide an independent assessment by a similarly qualified person or persons on the way the pilot conducts the activity and to identify any incorrect techniques or practices that the pilot may have developed over time. It is not intended to be a flight test for the renewal of the permission, but an opportunity for constructive discussion with other practitioners with a view to enhancing the safety of a pilot's performance.
7.28.3 The following is the recommended procedure for the peer review process:
- The pilot should have had sufficient recent practice and/or training to be able to conduct a sequence of low-level aerobatics safely
- The pilot should brief the observer(s) on the sequence to be flown
- The pilot should fly the sequence under observation, either from the ground or the aircraft down to the level of the permission, or the level to which the pilot intends to exercise the permission, if higher
- After the flight, the pilot and the observer(s) should de-brief the sequence to identify ways in which performance and safety could be improved; and
- The review is entered in the pilot's logbook and signed by the pilot and by the observers as a record to indicate that the observation and discussion has taken place. It could include a disclaimer that the observer is not certifying the pilot's competence
7.28.4 The observers would need to have proficiency in low-level aerobatics and preferably also in assessing low-level aerobatic performance. Suitable observers would be any one of the following:
- CAR 155 delegate; or
- At least two other low-level permission holders with similar permissions; or
- CASA Flying Operations Inspector (FOI).
7.28.5 During the debriefing process it is important to be objective in identifying items that were done well and those that could have been done better. Emphasis should be on providing input and advice on ways to improve safety and performance rather than on questioning an individual's ability.
7.28.6 Signing-off as an observer for peer review should not be construed as certifying the competency of the pilot, but that the review has taken place and that any issues of concern have been brought to the pilot's attention.
7.28.7 The object is not to assess the pilot as suitable or otherwise to continue to hold the permission, but in cases where continued operation by the pilot would constitute a serious risk to air safety there would be some moral responsibility for the participants to counsel the pilot and, if necessary, bring this to the attention of CASA.
7.29 Aerobatic Checks
7.29.1 Aerobatics, like any other flight activity, requires a system for checking essential safety items before, during and after every flight. The following checks are specific to aerobatics and are additional to the normal checking activities that should be conducted on all flights.
7.30 Pre-flight Planning
- Pilot is qualified and current for aerobatics
- Pilot physical and mental fitness for aerobatics
- Aircraft is suitable for planned aerobatics
- Aircraft limitations checked and known
- Day visual flight rules (VFR) with meteorological conditions suitable for aerobatics
- Suitable area selected
- Airspace and height limitations checked
- Manoeuvre sequence planned
- Manoeuvre safe entry parameters known
- Risk management reviewed; and
- For low-level aerobatics, check aircraft all up weight and the expected density altitude for the effect on performance
7.31 Pre-flight Inspection
7.31.1 A pre-flight inspection for an aerobatic flight will cover all the items for a normal pre-flight inspection, but with additional attention to items that are particularly critical to aerobatic safety.
Structure - check for visual evidence of damage or failure including struts and strut connections, elevator and rudder stops, wrinkles in the metal or fabric covering and looseness in any structural part. Also check control surfaces, cable trim tabs and actuating rods etc.
Seatbelts and shoulder harness - make sure the harness is suitable for aerobatics, is in good condition, and check that the latching mechanisms lock securely. Check that unoccupied seats have their harnesses secured so that controls cannot be fouled.
Doors and canopies - Check doors, windows and canopies for secure locking.
Controls - With all occupants seated and strapped in, ensure that the controls can be operated freely through the full range of movement and work in the correct sense.
Loose objects - Don't carry items that are not essential for the flight, and make sure any loose objects are secured or stowed. Check for foreign objects in the cockpit and in the fuselage to ensure that there are no loose objects which could jam the controls during manoeuvres. For all occupants, empty pockets or ensure that they are securely closed and that there are no loose items in clothing. Make sure the cockpit floor is clean and ashtrays are empty and closed.
7.32.1 If passengers are carried on aerobatic flights they should be fully briefed on aerobatic considerations:
- Safety harness is tightly fitted and secured at all times
- Seats securely locked in position
- Briefed not to interfere with controls
- Are they fit for aerobatics? (no illness or medical condition)
- The manoeuvres and sensations to be expected
- To alert pilot of feelings of nausea or problems with harness or seat
- Location of ventilation controls and sick bags
7.32.2 It is advisable not to subject passengers who are not used to aerobatics to -G loadings
8.1.1 Select an area that is not in congested airspace and is away from aerodromes and built up areas. CAR 141(2) precludes aerobatic flight in a flying training area unless it is in an aerobatics training area set aside for the purpose. Check that the area around and below is clear before performing spins or aerobatic manoeuvres, and maintain a lookout and listening watch for other traffic while performing.
8.2.1 Consider that your aircraft will be operating at high power settings during many aerobatic manoeuvres and minimise the noise effect by flying higher and over sparsely populated areas where possible.
8.3 Pre-aerobatic Checks
8.3.1 Prior to commencing aerobatic manoeuvres carry out appropriate checks. Use of the acronym HASELL is useful.
- Height - sufficient to recover by 3000' AGL (or the lower limit of the pilot's approval)
- Airframe - gear up, flaps up, trims within normal limits
- Security - harness secure, hatches closed, no loose objects
- Engine - instruments checked, mixture rich, carburettor heat checked, fuel adequate, fuel selections made
- Location - in an appropriate area, not over a built-up area, forced landing options reviewed, major features identified
- Look-out - clearing turns both directions and review between manoeuvres
8.4 Low-level Checks
8.4.1 The following additional checks can be performed at a safe height prior to conducting low-level aerobatics:
- Inverted check for loose articles and for aircraft systems functionality
- a slow loop to check aircraft handling characteristics
- a manoeuvre that takes a known height, to check aircraft performance and altimeter indications
- a G awareness manoeuvre, such as a high G turn. This should be three to five G for 10 seconds to allow the pilot to practice the G straining manoeuvre and to ready the cardiovascular system for high G. It is not to check maximum G tolerance
8.5 In-flight Exceedences
8.5.1 Monitor airspeed, engine and accelerometer indications during all manoeuvres.
8.5.2 If at any time during a flight the aircraft limitations are exceeded, the aircraft should be immediately returned to the aerodrome for an inspection by a licensed aircraft maintenance engineer (LAME). If something doesn't feel right during the flight, for instance abnormal control pressures or responses, unusual vibrations etc, the same advice applies.
9.1.1 Conduct a careful post-flight inspection of the aircraft to check for indications of overstressing or damage that may have occurred or become evident following the flight, as if you are about to fly the aircraft yourself. Look for the same items listed in the pre-flight inspection.
9.2 Maintenance Release
9.2.1 Enter damage, defects or exceedences in the maintenance release or flight technical log.
9.3 Responsibility To Other Pilots And Operators
9.3.1 To ensure that significant safety issues are not overlooked, the pilot has a responsibility to subsequent pilots, not only to enter defects or exceedences in the maintenance release, but to bring to the attention of the owner, operator or subsequent pilot, any matter about which there could be a concern in relation to airworthiness. A number of inflight airframe failures have been attributed to stresses experienced by the aircraft on a previous flight or accumulated over a number of previous flights.
9.3.2 Do not reset the accelerometer, leave it as evidence to the next pilot of the G loadings experienced.
9.4 Aerobatics Safety Summary
- Aircraft is airworthy and prepared
- Pilot physically and mentally ready for spins and aerobatics
- Know the limitations of both yourself and the aircraft
- In case of disorientation, plan to roll upright, level to the nearest horizon rather than pull through, and take time out to recover equilibrium
- Review the emergency spin recovery procedure for upright and inverted
- Review procedure for unusual attitude recovery
- Assess the possibility of GLOC in the manoeuvre sequence
- Do the full 'HASELL' check before commencing manoeuvres
- Use a clearing procedure before all manoeuvres
- Review the entry parameters for ensuring safe manoeuvring
- Start with sufficient height to give plenty of margin for recovery
- Maintain a good lookout during any sequence of manoeuvres
- Do not exceed maximum engine RPM or manifold pressure
- Monitor and react appropriately to engine temperatures and pressures, particularly during prolonged inverted flight
- Never exceed the G or VNE limits of the aircraft
- Do not make full-range or aggressive control movements near or above manoeuvring speed (VA/VMAN)
- Do not roll the aircraft above its rolling G limit
- Do not do flick manoeuvres above the speed stipulated in the flight manual
- Do not pull significant G above VA in turbulent conditions (a gust could overstress the aircraft)
- Constantly monitor your height for recovery margins
- Constantly monitor G forces in relation to physiological and structural limitations