THE MOST USEFUL INSTRUMENTS IN YOUR COCKPIT
Acknowledgements: THE UK CAA’S AIRPROX
SAFETY MAGAZINE 2017
Every
year there’s an increase in Airprox occurrences as the better weather arrives.
It’s probably no coincidence; those who aren’t hardy winter flyers get back
into the cockpit, perhaps a little rusty after a bit of a lay-off, and as a
result there’s a great temptation to focus on getting hands and minds
recalibrated rather than looking out. We see something like one mid-air collision
per 60 Airprox occurrences, so take a couple of minutes to remind yourself before
each flight of the risks and causes of Airprox, and when airborne use THE MOST USEFUL INSTRUMENTS IN YOUR COCKPIT
as much as possible - your EYES.
How
long do you reckon it takes from seeing another aircraft to hitting it – 30
seconds to a minute, maybe? NO! lf you’ve been
unlucky enough to have had a very close encounter you’ll know you have nowhere
near as long as 30 seconds to take action; a bit like a slow-motion train crash,
everything seems to take a long time until the last few moments when it all
happens in split seconds. Research shows that in normal circumstances the
average pilot and aircraft needs anything from nine to 12.5 seconds from spotting
another aircraft to processing the closure geometry and avoiding a potential
collision.
So,
take two PA-28s meeting head-on at around 90kt each; there’s around ten seconds
from the most eagle-eyed pilot being able to spot the other aircraft and
impact. The crucial thing here is that in the first five seconds little seems to happen with not much change in the
size or motion of the oncoming PA-28 - it’s only in the last five seconds that it suddenly blooms
in size; the mind then takes a couple of seconds to recognise it as a threat,
leaving just three seconds or so to take action. Naturally, the odds of
spotting a potential collision reduce in relation to time spent looking out,
and the best rule of thumb is 80 percent of the time looking out and just 20 percent inside the cockpit
in small chunks.
A
recent collision between two PA-28s shows just how looking down into the
cockpit can lead to trouble. The two aircraft were flying on a converging
track, and while one pilot looked down to set QFE on his altimeter in preparation for landing, the other looked down
at his map – moments later they collided. They were lucky, and
both were able to land safely. The AAIB concluded: ‘It is likely that poor
into-sun visibility, the constant angle between the tracks of the aircraft, and
the fact that the attention of both pilots was inside their respective cockpits
before the collision, contributed to the breakdown of the see-and-avoid.’
So,
looking for other aircraft is vital, especially before going head-down in the cockpit, but
just ‘looking’ isn’t enough. Even in a
featureless sky eyes tend to focus somewhere, but if there’s nothing specific
to focus on they revert to a relaxed intermediate distance, which means you don’t
necessarily see anything that’s going on out there. Movement is a very important
attention-getter, and with no visual clues there’s a tendency to focus at a
point in space one to two metres away; so, you’re not necessarily going to see
something at a distance. A periodic glance at objects such as the wingtips will stop this ‘empty field myopia’.
Colliding
aircraft have a relative bearing constant to each other until impact. The collision threat remains in the same place on
the canopy, so moving your head relative to the canopy or windscreen is an
important aid to a successful lookout.
A
collision threat’s size on the retina roughly doubles with each halving of the
separation distance, so colliding aircraft stay relatively small until shortly before impact when it all happens
rather quickly! This underlines the importance of apportioning the correct amount
of time for a systematic and repetitious scan pattern. ‘Lookout’ should be
performed using a series of small eye and head movements with intervening
rests, and whilst carrying out regulated scans might sound a bit formulaic they
do work. For example, the RULE OF 3s which involves
dividing your field of view into 3 zones, with 3 areas in each. Start scan on
centreline (greatest threat); return scan to centreline (greatest threat).
First look at centre 3, then 3 hops left; back to centre, 3 hops right; back to
centre, look inside.
No
one is immune from mid-air collision, but an understanding of the limitations
of vision, collision geometry and visual scanning technique will help to avoid
one.
Other
important aids to airprox avoidance include:
· Ears – communicate by talking/listening on the radio
to make your intentions clear and maintain situational awareness of others.
· Foresight – fly defensively, with vigilance,
courtesy and consideration for others (aka airmanship).
· Insight – review your understanding of ATC
services, rules of the air, circuit patterns and procedures.
· Advertise – make your presence known through conspicuity
measures (electronic and visual).
· Prioritise – time-share cockpit tasks and avoid distractions
compromising your lookout.
FLY SAFE!