The length of the vehicle and the presence of air brakes has absolutely nothing to do with whether or not a CDL is required to operate that vehicle. Zilch, nada.
What does matter is the Gross Vehicle Weight Rating of the vehicle. If it's in excess of 26,000 lbs., then a CDL will be required, unless it meets the exemption criteria for farm trucks, military vehicles, first response vehicles, or recreational vehicles.
However, ANY vehicle which is a bus designed to transport more than 15 persons (including the driver) and ANY vehicle hauling a quantity of hazardous materials requiring placards to be displayed requires a CDL, regardless of vehicle GVWR (Class C for single vehicles or combinations under 26,000 lbs. GVWR/GCWR, Class B for single vehicles in excess of 26,000 lbs. GVWR or combinations in excess of 26,000 lbs. GCWR if the vehicle in tow has a GVWR of 10,000 lbs. or less, Class A for a combination in excess of 26,000 lbs. GCWR when the vehicle in tow has a GVWR in excess of 10,000 lbs.).
If it's a vehicle with a GVWR in excess of 10,000 lbs. and is being used for commercial purposes, you will, however, need a current DOT medical card.
Air brakes have absolutely ZERO determination in whether or not a vehicle requires a CDL.
Only if it's a: transporting hazardous materials or b: a bus designed to transport more than 15 persons (including the driver).
Only if it's carrying hazardous materials in an amount requiring it to be placarded, or if it's designed to transport more than 15 persons (including the driver).
No. Air brakes are not a parameter in determining whether or not a vehicle needs a CDL.
To answer you we need to know what country's traffic regulations you are asking about.
The air brakes are irrelevant. And you'd need a medical card in that instance if you were doing interstate operations, but not intrastate operations.
Try looking for "air brake endorsement" in the NY driver's manual. You'll notice there isn't mention of one. The reason is because there isn't one. For a CDL driver, if they do not complete and pass the written air brakes test and then conduct their road test in a class appropriate vehicle equipped with air brakes, then they get a restriction which bars them from operating an air-brake equipped commercial vehicles.
Only in cases where the vehicle fits the criteria where it requires a Class C CDL. Examples would include vehicles designed to carry more than 15 passengers (including the driver), and vehicles carrying hazardous materials in a quantity sufficient to require placards to be displayed. If a vehicle under 26,000 lbs. does not meet the criteria where it requires a CDL, then it can be driven on a regular Class C licence, whether it has air or hydraulic brakes, without any additional testing.
Not unless it's a bus designed to transport more than 15 passengers (including the driver).
In the US, no - there is no such thing as an air brake endorsement - only a restriction for CDL holders who don't pass the written air brakes test and complete the pretrip and road tests in a vehicle equipped with air brakes, which prohibits them from operating vehicles requiring a CDL which are equipped with air brakes.
In some instances, yes.
No.