Mandatory spin training has been removed from the PPL course for nearly 40 years now, and the current alternative emphasis on stall spin awareness and avoidance is very well established. Although Flying Instructors must complete full spin training during their FI course, it is likely that most private pilots have little experience of the regime beyond the stall. So, what is spinning really all about?  

The Incipient Spin 

An incipient spin occurs if a wing drops as an aircraft stalls. If recovery is not promptly initiated, the roll will automatically continue towards the downgoing wing; this is called autorotation. If the autorotation remains unchecked, a number of unsteady manoeuvres in yaw, roll and pitch will occur and the aircraft will enter a full spin.

Recovery during the autorotation stage must remove the stalled condition and prevent further yaw and roll. If departure from normal flight is detected with buffet and undemanded roll, the controls and rudder should be promptly centralised and held. The aircraft may recover in an unusual attitude, which, once unstalled may require further careful use of controls to recover. 

The Fully Developed Spin

In a fully developed spin, the aircraft is fully stalled and is following a spiral decent path. The aircraft will be simultaneously yawing, pitching and rolling about a vertical spin axis and there will be a complex interaction of aerodynamic, inertial and gyroscopic forces acting. 

Common characteristics of the fully developed spin are:

• A high rate of rotation

• A low nose attitude

• A very high rate of descent

• A steady airspeed (of note, an increasing airspeed generally indicates a steep spiral descent)

 The high rate of descent makes the fully developed spin particularly hazardous, as prompt recognition and recovery action is required before the aircraft gets too close to the ground. Even so, a spin from low level flight such as whilst flying in the circuit may not be recoverable which is why so much emphasis is placed on stall spin avoidance in training. 

Standard Spin Recovery

You may often hear and read of the ‘Standard Spin Recovery’. In reality, this is somewhat of a misnomer as the only appropriate spin recovery actions are those which are published and approved for your particular aircraft in the Aircraft Flight Manual / Pilots Operating Handbook.

Whether you are flying an aircraft certified for intentional spinning or not, it is important you read up on what the correct actions are for your particular variant and type of aircraft if they are published. 

Here is a typical spin recovery technique from the Firefly T67M: 

Applying incorrect spin recovery actions can delay or compromise recovery, potentially leading to a dangerous or even fatal loss of height. The following accident report is an example of where the pilot may have sadly applied the technique for a previously flown type at too low a level for recovery to be effective: 

Precautions for Spin Training

Like many activities in aviation, spinning is not inherently dangerous, but it is unforgiving of mistakes or a lack of attention to detail. Whether you are a competition aerobatic ace or just someone wanting to do a little bit of dual spinning for the experience, some precautions and preparations are key.

A suitable Aircraft 

It goes without saying that any aircraft used for developed spin training must be certified and approved for intentional spinning. It is also worth reviewing the individual aircraft though - are there any deferred defects which could affect things? Is the aircraft sanitised of all the extra loose articles that can be found in the typical club aircraft? Is the cockpit clean and free of loose debris? 

Currency and Competency 

It is vital that any pilots and instructors involved are both trained and current to undertake spin training - an instructor who last spun on their renewal 4 or 5 years ago is probably not in good enough recent experience themselves to be training others. If in doubt, or not fully confident about any aspect of spin training, get some dual refresher experience with someone who is qualified and current to do so. 

Pre-Flight Briefing

A calm and unrushed pre flight briefing is the time to go through the aircraft manuals, plan for the flight and cover some emergency scenarios. It is also very important to perform an accurate mass and balance calculation - attempting spinning with the aircraft overweight or out of centre of gravity position limits is very dangerous and could result in the aircraft failing to recover. 

Pre-Flight Checks

During your pre-flight checks is also a good time to do a ‘dry run’ of the actions and control inputs for spin recovery. Practice instinctively selecting the neutral position for ailerons, elevator and rudder and check the actual control positions are neutral and you are getting the true neutral position. 

Airborne Checks 

As for any general handling exercises, it is vital that spin training is performed in a suitable operating area with regard to airspace, weather and clear of built-up areas. Remember to pre-brief this element of the flight and use the HASELL checks:

·       Height –  sufficient to be sure of recovery by the base height which is normally 1,000 ft

·       Airframe – correctly configured for the manoeuvre, e.g. flaps up, windows closed, correct fuel tank selected perhaps booster pump on

·       Security – straps tight and locked, no loose articles

·       Engine – Temperatures and Pressures good, mixture appropriately set for lowest anticipated height

·       Location – Not in or near controlled airspace, not above built-up areas, a suitable location

·       Lookout – a proper lookout to ensure no collision risk will occur. This normally involves a minimum of a 180 degree turn or 2 x 90 degree turns.

A good practice is to expand the usual HASELL checks to HASELL+ checks:

The + elements confirm that the aircraft canopy is clear of condensation or ice, there is a good visual horizon all around and the aircraft is not above a monochromatic surface such as the sea or a flat overcast (which could compromise the usual assessment of yaw and roll). There should also be a brief to ensure both pilots know who is doing what, and what actions to take in the event of an emergency or unexpected events. 

Parachutes…

The use of parachutes for spin training can generate different opinions. Whilst it is ultimately down to personal choice in light aircraft in the UK, should you use them it is vital that any parachutes are correctly maintained, in date on their servicing cycle and you know how to handle, protect, and operate them. The aircraft doors / canopy should also be capable of handling an emergency exit with a parachute and the parachute should not compromise your seating position or flying control movements. You should also factor minimum abandonment heights into your briefings and operating calculations. 

Useful Experience

While it may be unusual and challenging, gaining some experience of spin training with a qualified and current instructor in a suitable aircraft, can be a useful knowledge and confidence booster. It could also be a worthwhile exercise for your next biennial instructor flight! 

Useful references:

British Aerobatic Academy - HASELL checks and why do we do them

https://www.airpilots.org/file/666/teaching-stalling.pdf

https://bura.brunel.ac.uk/bitstream/2438/4129/1/Fulltext.pdf

https://www.gasci.ie/uprt-stall-spin-awareness.html