Helicopter Safety - Human Factors
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The area at the end of the tail boom of a helicopter is very dangerous. It is here where the tail rotor can be found, and a tail rotor running
at full speed is lethal. However, this is not obvious to the untrained (ground) crew, let alone to a passenger. Therefore, everyone who will
be getting close to a helicopter should be briefed about the dangers of the tail rotor. Tail rotors are so dangerous because they are typically
at chest and/or head height, and a turning tail rotor is also very difficult to spot.
The main rotors are, of course, also dangerous when someone gets close to them. Again, all of the people involved with a flight should be briefed
about the do's and don'ts. Examples of things going wrong are, people waving while under the rotor disc, and people running beneath the rotor
disc because the downwash blows something away.
Special care should be taken when the rotors are starting to turn or stop. In these circumstances the pilot’s controls are not particularly
effective, and more importantly, the rotors are not straight horizontally because of the lack of sufficient centrifugal
forces (the forces that level the rotors when rotating at high speed). The problem is that rotor blades can flap and are flexible, and at low speeds,
they can do so with significant displacement. It is very easy for a wind gust to flap down a rotor during the engine start or power down.
In these circumstances someone can be easily struck. Of course, passengers do not know this in advance of a flight.
Another rotor disc related danger is the result of loose objects getting caught up in the downwash of a hovering helicopter, and thus being
lifted on the re-circulating air, eventually hitting the rotor disc on the up side.
- Brief passengers and ground crew about the dangers of the rotors
- Watch for people who are heading for the tail rotor area. Try to stop them immediately
- Never raise your arms when under the rotor disc
- Never throw objects underneath the rotor disc
- Never embark or disembark a helicopter when powering up or shutting down.
- If possible, embark or disembark when the engines are shut down.
- Look for loose objects when commencing a hover. A running down landing is less sensitive
to loose objects as there is much less re- circulating air.
Your capability as a pilot is an important factor in the safety of you and your passengers. Always assess your own capability and act accordingly.
Is the weather not as good as you would like, and you are not that experienced? Change your plans accordingly (or don't fly). If you are not
completely rested, then do not commence an exhausting flight. Know what can and cannot be done in the particular helicopter type. And should
things go wrong, always try to keep flying. Too many accidents happen because the pilot is busy analysing and solving a problem, and simply
forgets to fly the aircraft.
- Always fly within the safety limits of your helicopter.
- Know the characteristics of the type of helicopter you are flying.
- Take your own condition into account. Don't push yourself too far.
- Stay fit.
- Don't drink alcohol or use any drugs
- Helicopters are marvellous machines. They make you feel that you are actually flying
like a bird. However, be aware that spectacular manoeuvres can soon become dangerous
- When having problems, keep flying the aircraft, always!
- Be sure to understand the basic helicopter flight principles; this will help you to resolve problems when they occur.
- Follow procedures.
- When having problems, use every resource available: passengers, ground personnel,
tower, other pilots (use your radio). Consult your documentation, and always observe
the helicopter (uncommon noises, vibrations, 'feel' of control gauges, etc.).
- Regularly undergo training on incident handling.
- Prepare for spatial disorientation. Know that your instruments (e.g. the attitude
metre) are probably not wrong. Every pilot can get spatially disoriented.
Many helicopter crashes are caused by either a too big, or an unbalanced, helicopter load. Always pay attention to the maximum allowed load,
and take humidity, temperature and elevation into account. Know the capabilities of the helicopter you are flying. The Centre of Gravity (C of G)
of helicopters cannot be significantly changed without causing problems. If the C of G is outbound, the helicopter will bank and / or dip,
making landing dangerous. Also pay attention to objects that are not fixed, or are loose in the cockpit. They can obstruct vital
mechanisms (an example is an unattended mobile phone obstructing a jaw pedal).
- Take fuel, passenger, and cargo weight into account.
- Do not always trust weight figures. You are responsible and knowledgeable, whereas
other people may not even be aware of the problems they can cause.
If it goes wrong, you (as a pilot) will be blamed.
- Take into account the weather conditions. More elevation, higher air temperatures,
and humidity make
for less load capability. Low atmospheric pressure makes the situation worse. Wind also has a big influence on the lifting capability of helicopters.
- Assess the balance of your helicopter when hovering. Pay attention to the position
of the cyclic.
- When having problems with too much load, consider 'dumping' it (cargo).
- Brief passengers, and tell them not to suddenly change their position in a helicopter,
this will introduce a sudden change in the C of G, which may not be compensated for.
- Do not leave objects unattended in the cockpit. They can obstruct vital controls.
Pilot and passenger clothing
Finally, attention should be paid to clothing and protective wear. As a pilot, you should wear clothing that can protect you, at least to
some degree, against the cold, and fire. A pilot’s helmet has prevented many severe head injuries. Do not underestimate the forces that a
crashing or wildly spinning helicopter can bring to bear on your head.
Passengers should also pay, at least some, attention to the kind of clothing they are wearing. Airliners will not tell you about this
because they do not like to draw attention to the role of the passenger when it comes to safety issues, because they want to present
(helicopter) flying as being completely safe. However, the chances of suffering less severe injuries are greater when protective clothing is
worn. Obviously, jeans protect more than silk or synthetics, which are highly flammable.
- Wear appropriate clothing, with at least some degree of protection against cold, fire
and mechanical impact.
- As a pilot, wear a helmet.
Don't Get Caught in a Fatal Trap!
A vital resource for pilots, technicians, and helicopter enthusiasts, this book analyses every possible helicopter
accident in detail. It looks at accidents that have been caused by a broad range of factors, such as technical
problems, weather influences, mechanical failures, human factors, and many more. The treatment and analysis of
each cause is dealt with in depth. What makes this text invaluable is that throughout this work an attempt is
made to analyze accidents with a view to finding common causes, solutions, and enabling preventive measures to be
defined. This makes 'Fatal Traps for Helicopter Pilots' a potential life saver.