I'm surprised a certain Capt. Lappos hasn't already joined in, take that as a clue.
As I said, the terms V1 (TDP) , V2 and Vy relate to Class 1 / Perf. A Operations. V1 & V2 are derived from graphs taking into account density altitude and aircraft mass and are bugged on the ASI before takeoff. Vy is given for sea level conditions and is deemed to reduce at a standard rate with increased altitude. For V1, read Takeoff Decision Point (TDP) if you prefer.
Below V1 (TDP), in the event of a single engine failure the aircraft cannot climb away and is landed back on. For the type I fly, this ranges from 30 to 49 kts, depending on prevailing DA conditions.
Above V1 (TDP) the aircraft can be flown away on the remaining engine. V2 is held until obstacles are cleared (40 to 59 kts on said type), then IAS is increased further to Vy, which by definition gives the best ROC.
Last edited by ShyTorque; 4th Mar 2006 at 10:41.