Coaching Corner… Being on the lookout

PCS Head of Training David Cockburn discusses the ‘block’ system of scanning. And ponders if he has stumbled upon the secret of avoiding the problem of muscle memory…

Afew months ago I wrote about Airprox. We all know that it is vital to keep up a good lookout scan when we’re flying, because even the most sophisticated electronic ‘conflict alerting’ system can’t warn us of every aircraft which might hit us. For more detailed advice on the subject, I do recommend the CAA’s Safety Sense leaflet 13 on Collision Avoidance, which can be downloaded from its website. It offers a lot of good advice, only some of which I have space to repeat here.

Effective scanning is accomplished by a series of short, regularly spaced eye movements that bring successive small areas of the sky into the central area of vision where objects, which are not moving across the visual field, can be identified. Each movement should not exceed 15°, and each area should be observed for about one second (for those of us of a certain age, at least one-and-a-half seconds) to enable detection. Each pilot should develop the scanning pattern that is most comfortable for themselves, and then keep to it.

Peripheral vision can be useful in spotting collision risks if we are manoeuvring, but in steady flight the thing which is going to hit us will have no relative movement across our vision, so identifying such a threat needs time for our eyes to focus. If another aircraft appears to have no relative motion in relation to you, but is increasing in size, take immediate evasive action.

The leaflet describes scanning patterns to cover the most hazardous areas, and these involve the ‘block’ system of scanning. The viewing area (windshield from wingtip to wingtip) is divided into segments, and the pilot methodically scans for traffic in each block in sequential order. In my case, after a rapid scan of the essential instruments inside the cockpit, I start in the centre block of the visual field (centre of front windshield); move to the left, focusing for a second-and-a-half in each block, then swing quickly back to the centre block after reaching the last block on the left (where my wingtip can help indicate my attitude hasn’t changed) and repeat the action to the right, in a similar fashion to the picture shown, but extending further to the sides. After checking instruments again, I repeat the external scan.

I have to admit that such a scanning technique can be tiring and I’m sure I’m not alone in finding it difficult to keep it up conscientiously for more than a few minutes. Partly because I’m looking for my planned navigation features in the centre of my field of view, after a while I find my lookout scan concentrating more towards that central area. I need to actively remind myself to increase the area of my scan. For that reason I try to identify likely areas of high collision threat during my pre-flight planning, so that as I approach these high threat areas I can remember to reinvigorate my efforts.

Even in a slow moving aeroplane, the greatest threat is likely to appear within about 45° of the nose, so a restricted scan may not increase the collision hazard too much. However, trials carried out several years ago found that objects the size of a light aircraft are unlikely to be identified as collision threats until they are about one-and-a-half miles away, and closer if head-on. Even if the other aircraft is travelling across our flight path, at 120kt we can expect to cover that distance in about 45 seconds, and if it is coming towards us we can halve that time. Every pilot takes a finite amount of time to react, and the aircraft itself needs time to follow a control input, so I suggest that if we look inside the cockpit for more than about 10 seconds we are unlikely to see another light aircraft in time to avoid it. Those of us flying faster aircraft can’t afford that long.

A dirty windscreen or goggles will reduce the distance at which we can identify a threat, so it helps to keep these clean. Glare doesn’t help, so I recommend a good pair of sunglasses or tinted goggle lenses when the sun is shining, especially if it is low in the sky.

We do need to spend some time looking inside at gauges and displays, so I split checks into very short chunks, and try to carry out a full lookout scan before any check that will require me to look inside for more than a glance, and scan again immediately afterwards. We also need to check and sometimes add information on our chart or PLOG. So I lift these up to a position just below the coaming to minimise the amount of distance I have to move my eyes and the time taken to do so.

There are other ways to reduce the amount of time spent looking inside. Some time ago I realised that although optometrists assessed my eyesight as being quite good enough for a Class 2 Medical, I was having to look carefully and spend time focusing on things like the frequencies marked on my chart. When somebody lent me their reading glasses (I think they were +1.5 strength) I discovered that not only did things become clearer, but it took me much less time to focus, and therefore I was looking inside for a much shorter time.

As it happens I was fortunate at that time to find a company selling sunglasses with reading cut-outs at the bottom, and these have proved an excellent investment. That supplier is no longer trading, but a quick internet search will find other companies that can provide similar items. My legally required ‘additional’ pair are of the ‘half-moon’ type reading glasses, and I use these when glare is not a problem. I have found the ability to read charts and other details rapidly has improved my lookout considerably and I suggest others will find a similar benefit, even if, like me, they are not legally required.

Threats and Errors – muscle memory?

It is always nice to be complimented, but I was a bit disconcerted when I received this in an email from one of our members:

“Really enjoyed your latest article as I sit here in a neck brace following a take-off accident in a Taylor Monoplane. I believe a major factor in the accident was the muscle memory that had me wrongly adding right rudder. I only realised this after the tail came up and the VW engine was taking me off to the right. The day before I had been behind a C90 in an Emeraude, so more conventional prop rotation.”

That got me thinking about my own experience some years ago when a microlight instructor had taken me for a flight in a flexwing, during which he had demonstrated that it was in fact fully controllable, albeit in a different way to that with which I was familiar. He then put me in the front seat and I taxied to the holding point. Well, I say I taxied, in fact I immediately realised that 10,000 hours in three-axis aeroplanes and gliders had so conditioned me to apply rudder in what was now a natural sense to counter yaw that I was totally unable to steer the thing on the ground, even though as a schoolboy I had driven soap box carts which also steer by pushing the opposite foot to the intended turn. I declined his offer to fly the take-off because I was sure I’d kill us both, and I’ve stuck to three-axis aircraft ever since.

Above If you swap between different types, could your ‘muscle memory’ get you into trouble?

However, I’ve happily flown more than 1,000 hours behind Gipsy engines (mainly on Chipmunks) and a lot more on engines which rotate the other way, including quite a few on Chipmunks with Lycomings, so a change in engine rotation can’t be having the same effect on my brain as the change in steering effect. Have I discovered the secret of avoiding the problem of muscle memory?

Well actually, I think the reason I could adjust for whichever engine rotation I’m faced with was that at an early stage in my flying I did a lot less studying about the aircraft I was due to fly than I should have. I could never remember which way any particular aircraft was going to yaw when I applied power, so unconsciously my threat and error management consisted of preparing myself for it to surprise me. I can’t pre-condition myself so I have to be ready to apply rudder to counter whatever yaw I see actually starting (although I have to remember, it will try to yaw – I did have a bit of a surprise when I started to take-off in a twin without contra-rotating propellers).

Of course, as a glider pilot I am very used to operating the rudder in flight, because even at relatively high speed they not only have to counter aileron drag, but the secondary effect also assists roll control.

The same applies in an aeroplane, especially at low speeds, but they are also needed to counter unwanted yaw from the engine torque. I imagine the vast majority of my readers are experienced in identifying unwanted yaw and co-ordinating their stick and rudder, but if you feel your aircraft handling would benefit from some guidance, I suggest you contact your local Coach.

Details can be found on the Pilot Coaching Scheme part of the LAA website. ■

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