Aircraft Ceiling
 

Why is it that aircraft ceilings end with 100 ft.

ie B737 ceiling 37,100

B737NG ceiling 41,100

Why can't it just be 37,000 or 41,000ft. Just interested in knowing

Don't know. Dash 8 ceiling is 25,000' as far as I'm aware. Do you have a broader range of examples?

In some parts of the world, it is deemed prudent to offset your ATC-assigned altitude a bit for extra collision avoidance insurance. This may be a part of it.

Autopilot tolerance?

Some countries use the metric system.

If one climbs to the max AFM alt and slightly overshoots or sits in the crz slightly higher than say FL 410 (eg 41050) maybe as a result of turbulence, one has not intentionally busted a AFM limitation..... In otherwords it's a buffer to keep you legal.

I think that slamer came close to the mark. It's to keep you legal if you're right at the aircraft's upper limit.

In my experience, it seems to be a Boeing thing, to add to your Boeing list novicef, the upper limit for the B777 is 43,100 feet. It's testing my memory and I stand to be corrected, but I recall the limit for the B727 as being 42,100 feet.

Regards,

Old Smokey

I think you'll find it originally came from "Soft Cruise' mode or 'Alt Crz' mode of autopilot operation. This was designed to allow the aircraft to drift within this band (+/-100') rather than adjust the engine thrust to allow for minor speed discrepencies.

Aerodynamics. I think its all about aerodynamics. The EXTRA 300S ceiling is 15,000 ft. The thrust isn't too big. Military aircraft have superior aerodynamics and superior thrust. Thats why they have high ceilings...Plz correct me if i'm wrong.

Military aircraft have superior aerodynamics and superior thrust.

The G.E. engined B777-300ER has 115,000 Lb of thrust. Do any superior military aircraft have that much thrust? :=

Regards,

Old Smokey

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 :ugh:
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 :ok:

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)

Or another factor that sometimes limits the maximum flight altitude is the time to descend to 10,000ft following a decompression - all sorts of factors can affect it.
However, I think that the reason for the odd 100ft is, as [B]Slamer[[B] says, to keep you legal cruising at the top level. Only Boeing seem to worry about it though.:hmm: