Aircraft Rental Prices
Tecnam P2002-JF (EI-WFD and EI-WAT)
> PPL Hire: €115 per tach hour
> Student Hire: €115 per tach hour + Instructor fee (€50 per Clock hour)
Piper Warrior PA28-161 (EI-DJM)
> PPL Hire: €135 per tach hour
> Student Hire: €135 per tach hour + Instructor fee (€50 per Clock hour)
What is the difference between tachometer time and Hobbs meter time and how are they both measured?
The tachometer is actually a measurement of engine hours. For example, at sea level (SL), your engine’s ‘red line’ may occur at 2700 RPM – this is the engine speed which develops 100% power. If you run the engine at 100% power for 1 hour, then you have used 1 tach hour. More usually, we use 75% power and less. At most high cruise altitudes, 75% power RPM settings are very close to 100% power setting RPM's at SL, so tach time will be very close to real time in cruise configuration.
The Hobbs meter records real time, or 'clock time', and is activated by oil pressure. For many aircraft, this means that as soon as the engine is started, the Hobbs meter is activated. This measurement of flight time is completely independent of engine RPM settings. Most instructor fees are based on Hobbs time but it is more usually called 'Clock time' in this case.
The differences between the two measurements are noticeable when, for example, you are operating from a busy airport where ground delays are common. While the Hobbs meter is ticking over in real time, the tachometer will be ticking over in accordance with idling engine speeds. In this case, the tachometer will lag the Hobbs meter. On the other hand, if you spend very little time on the ground at idle and more time in the air, tach time and Hobbs time will be very close.