Pipistrel Virus 912, Flight And Maintenance Manual, Page: 84 / 108

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Appendix
How much difference is there between IAS and TAS
in practical terms?
Data below are valid for Sinus ultralight motorglider and Virus 912 aircraft flying in standard
atmosphere. To obtain correct speeds for particular atomospherical conditions please take advan-
tage of the table on page 85 of this manual.
The table below indicates how fast you may fly at a certain altitude to maintain
constant True AirSpeed (TAS).
TAS [km/h
(kts)
] IAS [km/h
(kts)
] TAS [km/h
(kts)
] IAS [km/h
(kts)
]
1000 m 3300 ft 250
(135)
237
(128)
270
(145)
256
(138)
2000 m 6500 ft 250
(135)
226
(122)
270
(145)
246
(133)
3000 m 10000 ft 250
(135)
217
(117)
270
(145)
235
(126)
4000 m 13000 ft 250
(135)
206
(111)
270
(145)
226
(121)
5000 m 16500 ft 250
(135)
195
(105)
270
(145)
217
(117)
6000 m 19700 ft 250
(135)
187
(101)
270
(145)
205
(110)
7000 m 23000 ft 250
(135)
178
(96)
270
(145)
196
(103)
8000 m 26300 ft 250
(135)
169
(91)
270
(145)
185
(98)
The table below indicates how TAS increases with altitude while keeping IAS constant.
IAS [km/h
(kts)
] TAS [km/h
(kts)
] IAS [km/h
(kts)
] TAS [km/h
(kts)
]
1000 m 3300 ft 250
(135)
266
(144)
270
(145)
289
(156)
2000 m 6500 ft 250
(135)
279
(151)
270
(145)
303
(164)
3000 m 10000 ft 250
(135)
290
(157)
270
(145)
316
(171)
4000 m 13000 ft 250
(135)
303
(164)
270
(145)
329
(178)
5000 m 16500 ft 250
(135)
317
(171)
270
(145)
345
(186)
6000 m 19700 ft 250
(135)
332
(179)
270
(145)
361
(195)
7000 m 23000 ft 250
(135)
349
(188)
270
(145)
379
(204)
8000 m 26300 ft 250
(135)
366
(198)
270
(145)
404
(218)
As you can see from the table above the
diferences between IAS and TAS are not so little and
MUST be respected at all times!
REMEMBER!
• Do not trust your ears.
• Do not trust your eyes.
• Trust the instruments and be aware of the IAS to TAS relation!
Always respect the limitations prescribed in this manual!
Never exceed the VNE as this has proved to be fatal!
Keep that in mind every time you go flying. Pipistrel d.o.o. wishes you happy landings!