Hi Jessop,

The cabin pressure has very little to do with the size of the aircraft - all passenger airlines have to have pressurised cabins and the safety standards don't usually vary with the size of aircraft but most airlines allow it to drop below 1 atmosphere pressure (ie what it is at ground level) because of the cost involved in maintaining air pressure and to reduce the stresses on the fabric of the aircraft.

I suspect that the length of the flight and the cruising altitude are more important than size of aircraft. The higher the cruising altitude the greater the differential between the internal and external pressure and the more pressure on the fabric of the aircraft if the internal pressure is kept at 1atmos and the greater the likelihood of air 'leaking' away through any imperfect seals etc. And I suspect the fuel costs involved in maintaining pressure increase the longer and higher the flight and hence the incentive to allow pressure to fall too. Nearly all my flying with BA is on flights of less than 90mins and the actual time spent at 34,000 ft is negligible compared to the 5 hour charter flight to the Gambia which gave me the most trouble and this alone might account for why I find flying BA more comfortable.

SM