Hobbs v. Flight Time Variance (G1000)

[SlowFlight]

I'm curious what variances you see on your G1000 '40s between the Hobbs and the flight time reported on the G1000. I have 1,111.6 on the G1000 and 1444.6 on the Hobbs.

[CFIDave]

Your ratio between the Hobbs and G1000 time in service ("tach time") looks quite normal, since the Hobbs also includes all the time you spend on the ground during taxi, run-up, going through checklists, waiting for clearances, etc. The G1000 only counts time in the air.

DA40s that are used for flight training tend to have a greater spread between the two counters, since training aircraft tend to spend proportionally more time with the engine running on the ground.

When we sold our DA40 a few years ago we had 663 hrs on the G1000 and a little more than 800 hours Hobbs.

[Fred]

Your ratio between the Hobbs and G1000 time in service ("tach time") looks quite normal, since the Hobbs also includes all the time you spend on the ground during taxi, run-up, going through checklists, waiting for clearances, etc. The G1000 only counts time in the air.

DA40s that are used for flight training tend to have a greater spread between the two counters, since training aircraft tend to spend proportionally more time with the engine running on the ground.

When we sold our DA40 a few years ago we had 663 hrs on the G1000 and a little more than 800 hours Hobbs.

I have exactly 25% less Tach then Hobbs time with my Hobbs reaching 1,900 recently.

[Rich]

Tyson, this is almost exactly what my plane is at, with the VM1000 recording the flight hours. I'm not sure how the G1000 operates exactly, but the VM1000 actually doesn't record all flight hours, quite. It doesn't count time while the RPM is below 1,500, which typically happens on the last phase of approach to landing. And of course, ground operations excluding runup.

[Charbie]

The greater the percentage of short flights, the greater the discrepancy. I have 356 air time and 687 hobbs time.

[rwtucker]

Then there is the Hobbs time some of us created when we forgot to turn off our left seat map light.

[Joey]

Just came out of annual so I just happened to write both down: g1000 engine page: 820 and Hobbs: 1019

[Kent Shook]

I have exactly 25% less Tach then Hobbs time with my Hobbs reaching 1,900 recently.

We're pretty similar - Just a few hours shy of 1900 on the G1000, with 2500 and change on the Hobbs.

[carym]

I'm curious what variances you see on your G1000 '40s between the Hobbs and the flight time reported on the G1000. I have 1,111.6 on the G1000 and 1444.6 on the Hobbs.

Tyson, this discrepancy is based (in part) on the fact that the G1000 is set to start timing after a certain airspeed is reached. I have found that my "Hobbs" adds about 0.2-0.3 hours to the G1000 time for each flight, and this is the amount of time it takes for me to taxi and run-up before the flight and to taxi back after the flight. Since most of my hours are x-country hours the discrepancy is not as great. If I am doing a lot of stop&go practicing, or x-wind landing practicing, the discrepancy is going to be much greater.

[rwtucker]

Curious. How many other than CFIs, rentals, clubs, etc. use Hobbs? In terms of oil changes, etc. I care about time under power. Lots of older aircraft don't even have Hobbs. The percent of non-flight time a Hobbs adds to each flight is a function of the duration of the flight. Taxi and run-up time are more-or-less a constant. Since the majority of my flights are 30-45 minutes, Hobbs is a significant percentage.