Our weekend flying activities have been curtailed due to the arrival of our baby daughter. At what age would it be considered safe; in regards to protecting her ears from damage or injury due to noise and pressure changes, for her to fly and what precautions should be taken?

Congratulations on your new baby. I hope she gives you much pleasure and satisfaction and that she, too, will grow to enjoy aviation. Your letter raises a number of interesting issues so I'll devote this whole column to the topic of 'flying with infants (and children)'.

You mentioned your concerns about damage to your baby's ears due to noise and pressure changes. I'll address these as well as a couple of other matters worth thinking about: Air-sickness, fear of flying, and restraint / impact protection.

You will find, though, that providing your child is in good health and that you take a few sensible precautions she should be able to fly with you from a very early age.

Pressure Effects.

Children have the same gas containing spaces in their bodies as adults. Changes in pressure can, therefore, lead to the same sorts of discomforts and injuries in children as in adults.

While the anatomy of the Eustachian tube (connecting the inside of the ears to the back of the throat) in children is slightly different to adults no-one appears to be certain whether this makes any real difference in the aviation. It may be that a child's Eustachian tube is less likely to lead to ear pressure problems during flight than that of an adult.

A child is less likely to consciously clear their ears than an adult. Ear clearing is more likely to occur during sucking, crying, or jaw movement.

Most pressure related ear problems occur during descent, when the gas in the middle ear contracts. You and I will consciously 'pop' our ears during descent to avoid the pressure build-up and prevent ear injuries - a young child cannot do this. To avoid these problems it is wise to feed children during descent. This means their jaw and mouth are constantly in motion and their ears clearing.

In older children chewing gum is a good method of getting their jaws working and their ears clearing. The past airline practice of handing out boiled sweets before takeoff was of very little use - virtually no-one gets ear pressure problems during ascent - they'd have been much more use at the top-of-descent.

A child with a sniffle, a cold, glue ears or any other ear or throat problem is a different matter altogether. Such a child should not fly until they are completely well.

Gut pain and sinus pains are also possible in children during flight. Unlike ear problems these troubles tend to occur during ascent. While there's not a lot you can do about these problems I'm not aware of them causing any major difficulties. It would be prudent to avoid any foods known to cause 'gas' in your child and to keep a close eye on their comfort during flight, especially ascent and descent.

Another potential problem, especially during flight in pressurised aircraft, is dehydration. A child will dehydrate quite quickly compared to an adult. Mild dehydration can result in drying of the surface membranes of the mouth and ears. When dry these membranes, including the eustachian tube, won't function optimally and ear pressure problems might result.

Ensure that your child is well hydrated before and during flight. Certainly don't withhold fluids to avoid the inconvenience of wet nappies - an injured eardrum is a much greater inconvenience.

Feeding a child during flight can be a mixed blessing. While the sucking a jaw movement makes the ears more likely to equalize a quantity of air is invariably ingested with the feed and could, theoretically, lead to stomach discomfort during ascent. On balance the benefits far outweigh the potential problems.

Noise.

Children, like adults, can have their hearing damaged by excessive noise exposure. Exposure to high noise levels should, wherever possible, be minimized.

While GA aircraft are not terribly noisy (especially when compared to some of their military counterparts) their cabin noise levels are not insignificant. Your C172, cruising at 100 kts at 4000 feet, exposes you to approximately 91 dB(A) of noise.

Aircraft noise exposures are generally quite brief and unless the noise levels are extreme do not usually represent an undue hearing loss risk. Regular, long duration, noise exposures are a different matter altogether.

Noise concerns would usually not preclude a child from flying in an aircraft providing that some heed is taken to their hearing protection.

I wouldn't recommend earplugs but you might look around for child-size hearing protection earmuffs.

Air Sickness.

A child's susceptibility to airsickness usually peaks somewhere between the age of 4 - 8 years. It is lower in younger children.

All other things being equal: The earlier a child flies the more likely they are to acclimatize to the aviation motion environment and the less likely they are to be airsick. Some children, however, will get airsick (and/or carsick) no matter how early they are exposed.

Fear of Flying.

Regular exposure to aviation, especially when accompanied by parents enjoying themselves, should make flying a less threatening environment to children. From the families I know I've come to believe that the earlier a child is introduced to flying the more comfortable they are with the activity.

Of course if they are airsick or get sore ears every time they fly they aren't going to associate aviation with fun or pleasure.

Restraint and Impact Protection.

This is probably the most important issue concerning children in aviation. All passengers in an aircraft require 'adequate' restraint. What constitutes adequate restraint is not so straight-forward with infants and children.

My understanding of the regulations is that a child less than 3 years old and weighing less than 15kg can be 'adequately' restrained when held by a parent. While this requirement makes the life of airlines and commercial operators much easier I wouldn't recommend it. In the event of an accident involving significant impact forces it will not be possible to restrain a child held on your lap or that of your partner.

A secondary loop harness around the child's abdomen interlaced with the parent's harness will provide a greater degree of impact protection. These loops, however, have has concerns raised about their safety. It is conceivable that a child could suffer abdominal injuries if involved in an aircraft accident while wearing such a loop. The question has to be asked though - Would you prefer the risk of abdominal injuries to the risk of major head injuries during an impact?

In my opinion the best option currently available is to use an appropriate car seat / capsule to carry your child in the aircraft. This matter is addressed in the Civil Aviation Advisory Publication No. 235-2(0) of March 1992. Basically an Australian Design Standard approved seat is appropriate for fitting into your aircraft.

You should be aware, though, that the fitting of the seat/capsule to your aircraft must either involve no structural modification to the aircraft or be approved by CASA (CAR 35 I think). If your thinking about doing this I'd suggest spending a little time talking to your LAME about your placement and security options.

Older children can, of course, be strapped into the aircraft in an identical manner to adults.

In conclusion - There appears to be no overwhelming reason that an infant or child should not fly in GA aircraft providing a few sensible safety measures are observed.