Jet engines are designed to achieve their best specific fuel consumption at high rpm, which can only be achieved at high altitudes where the air density is low.

Thrust produced will be low enough to equal the required cruising thrust. Also high altitude gives the best operating conditions for the airframe i.e. minimum drag during the cruise.

Turboprops need relatively dense air for the propellers to work efficiently and at high altitude the density would be too low.

The critical point (CP) is a point on a track where it is as quick to go on as it is to turn back.

Also known as ETP (Equal Time Point) and PET (Point of Equal Time).

Because of the distance which has to be covered to reach 41.000 feet which may not be convenient for a short flight.

On long flights it is more typical to fly at 41.000 feet when the aircraft weight and performance allows.

Tire creep is the tendency of the tire to rotate slowly around the wheel hub as a result of a millisecond landing friction on the tire before wheel spin occurs.

Yes, it is important because if there is too much creep the tire can tear out the inflation valve and cause the tire to burst.

Basic Empty Mass (BEM) is the mass of the aircraft with the basic equipment, unconsumable fluids and unusable fuel and oil.

TAS will increase.

The critical engine of a multi-engine, fixed-wing propeller-driven aircraft is the one whose failure would result in the most adverse effects on the aircraft's handling and performance.

Due to the asymmetric blade effect (P-factor), the right-hand engine typically develops its resultant thrust vector at a greater lateral distance from the aircraft's C.G. than the left-hand engine.

The failure of the left-hand engine will result in a larger yaw effect via the operating right-hand engine, rather than vice-versa, and it is termed the Critical Engine. Since the operating right-hand engine produces a stronger yaw moment, the pilot will need to use larger control deflections in order to maintain aircraft control. Thus, the failure of the critical (left-hand) engine is less desirable than failure of the right-hand engine.

The operating right-hand engine will produce a more severe yaw towards the dead engine, thus making the failure of the left-hand engine critical.

Decision altitude (precision), the altitude at which a decision must be made during an ILS, MLS, or PAR instrument approach to either continue the approach or to execute a missed approach.

New York to London (flying east) would take less time because of the Polar front westerly jet stream.

36,090ft in ISA