Cabin Altitude

[whirlwind]

My question is about sinus difficulties etc - when not to fly. What is cabin altitude commonly set to when crossing the Atlantic, in say, a 747? If I can't clear my ears on the ground due to a heavy cold, am I likely to have a problem?
WW

[fujii]

Ask a GP or ENT.

[Tarq57]

Cabin altitude on most airliners is typically 8000 feet.

Problems with blocked sinuses typically result in painful ears, as the pressure may be unable to equalise. This happens on descent; the Eustachian tubes need to be physically opened for the air to equalise. During climb it's usually not a problem - the shape of the apertures allows the air out, a bit like a non-return valve.

Physically opening the Eustachian tubes to balance the pressure between the (inner) ear and the sinus is done by swallowing. In an unobstructed (and normal) system, that provides sufficient movement for the air to get through. When the sinus is blocked it may be necessary to pinch the nostrils closed and blow - not too hard. If that doesn't work you're in a spot of bother. A painful inner ear will ensue. A ruptured eardrum is the worst case scenario.

The trick is to clear them deliberately and frequently on the way down, before it gets to the point of painful ears. A difference in air pressure tends to hold the tubes closed, thus requiring a greater physical movement than swallowing might provide.

I'd strongly recommend a nasal decongestant, or a spray bottle with a saline solution in it, to prevent the mucus becoming too 'gunky', and therefore more likely to form a blockage that can't be moved. Use it regularly during flight. Air in the cabin is dry. Some people have reported success with hayfever medications designed to dry the sinuses out.

[BOAC]

A small correction there. The 'Eustachian tubes balance the pressure between the (inner) ear and the airway', not the sinuses. They have no direct connection to the sinuses. Clearing a blocked sinus is extremely difficult, and can sometimes be achieved by the Valsalva action Valsalva maneuver - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Valsalva_maneuver) but not reliably. Pain from descent with a completely blocked sinus can be excruciating. I once suffered this from a circuit detail in the RAF when descent from 1000' to ground level caused intense pain.

Do not treat a bad head cold lightly in aviation. fujii is spot on.

[KBPsen]

Another correction, cabin altitude is not "typically 8000 feet", it is between 6 and 7000 feet. On the latest types it is even lower.

[BOAC]

'Can be as high as' is more like it.

[whirlwind]

Thank you.
WW

[Notso Fantastic]

Well I think 8000' is more typical, especially in longhaul aeroplanes.

I believe the Stuka pilots used to open their mouths wide and scream in their dives which must have been quite painful. A good technique to try on an airliner! It'll get everybody clearing their ears quite effectively!

[Load Toad]

1) I find yawning helps.
2) An OTC nasal spray from Japan called 'Nazal'.