Why is it that aircraft ceilings end with 100 ft., ie B737 ceiling 37,100, B737NG ceiling 41,100
What are we writing about here?
It seems to me that the numbers quoted here are MAXIMUM FLIGHT ALTITUDES, and those have most of the time nothing to do with the CEILING of the aircraft.
The maximum flight altitude is obtained by factoring the desired service life of the airframe against the combination of stress and cycles (yes, caused by pressurization of the hull) during its projected life, while taking into account the consumption savings of the higher levels
There are some cases when the aerodynamics limit the aircraft (i.e. wings too small... ask the MD-90 jocks!), but the majority of airliners are power/aerodynamically able to climb higher than the defined maximum flight altitude
Service or Maximum Ceiling: under standard atmospheric conditions, altitude at which an airplane cannot climb more than 100 fpm
Absolute Ceiling: under standard atmospheric conditions, maximum altitude above sea level at which an aircraft can maintain horizontal flight (ROC = 0)