*‘VTOSS’ means take-off safety speed for Category A rotorcraft. 
‘VW’ means maximum winch-launch speed (JAR–22 only).    
*‘VY’ means speed for best rate of climb.  
*‘V1’ means take-off decision speed.  
*‘V2’ means take-off safety speed.  
*‘V2min’ means minimum take-off safety speed.     
‘V3’ means steady initial climb speed with all engines operating.

ALTITUDE (m) (pressure basis)
STANDARD CLIMATES – S.I. UNITS
Fig. 1

NOTES: (1)  This diagram gives envelope conditions for design purposes; it does not constitute an accurate representation of any particular climate.
(2) The line BC has no significance other than as illustrating the text.
TEMPERATURE (°C)
ALTITUDE (ft) (pressure basis)
STANDARD CLIMATES – NON S.I. UNITS
Fig. 1

NOTES: (1)  This diagram gives envelope conditions for design purposes; it does not constitute an accurate representation of any particular climate.
(2) The line BC has no significance other than as illustrating the text.
TABLE 1
RELATIVE PRESSURES AND DENSITIES – S.I. UNITS
Air density at sea-level (barometer 1.013250 x 103 Pa

temp 15°C) is 1.2250 kg/m3
Altitude (Pressure Basis) m  Relative Pressures (I.C.A.O.)  Relative Densities Associated with Conditions Stated 
International Standard (I.C.A.O.)  Tropical Maximum  Temperature and Arctic Maximum  Tropical and Temperature Minimum  Arctic Minimum 
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 7000 7500 8000 8500 9000 9500 10000 10500 11000 11500 12000 12500 13000 13500  1.000 0.942 0.887 0.835 0.785 0.737 0.692 0.649 0.608 0.570 0.533 0.498 0.466 0.435 0.405 0.378 0.351 0.327 0.303 0.282 0.261 0.242 0.223 0.206 0.191 0.176 0.163 0.151  1.000 0.953 0.907 0.864 0.822 0.781 0.742 0.705 0.669 0.634 0.601 0.569 0.539 0.509 0.481 0.454 0.429 0.404 0.381 0.358 0.337 0.317 0.297 0.275 0.254 0.235 0.217 0.200  0.906 0.862 0.820 0.780 0.741 0.703 0.668 0.633 0.600 0.568 0.538 0.509 0.481 0.454 0.428 0.404 0.380 0.358 0.337 0.316 0.297 0.279 0.261 0.244 0.229 0.214 0.201  0.951 0.905 0.862 0.820 0.779 0.740 0.703 0.667 0.632 0.599 0.568 0.537 0.508 0.480 0.453 0.428 0.403 0.380 0.357 0.336 0.316 0.296 0.276 0.255 0.236 0.218 0.201  1.138 1.072 1.010 0.955 0.908 0.862 0.818 0.776 0.735 0.696 0.659 0.623 0.589 0.556 0.525 0.495 0.466 0.439 0.412 0.388 0.364 0.341  1.291 1.190 1.097 0.011 0.949 0.892 0.837 0.792 0.750 0.709 0.670 0.633 0.597 0.563 0.531 0.500 0.470 0.442 0.415 0.389 0.365 0.341