Hobbs or FF? Time question

M

mryan75

Pattern Altitude
Joined
Jul 28, 2014
Messages
1,801
Display Name
Display name:
mryan75
I have a Hobbs meter in my Cherokee, and this is what I've always used to keep time for my logbook. When FF started keeping track for me (I guess it just did it automatically, I never asked it to), I noticed that the total times were less than what the Hobbs indicated. So I stuck with the Hobbs and never gave it another thought.

The other day after a flight I was looking through FF and saw the logs again. I double checked that flight and some of my older flights, and on average I'd say FF "gives me more time" than the Hobbs. I know it doesn't matter to those of you with a few thousand hours, but to a guy building time every tenth counts.

So my question is: do I have to be consistent with which measurement I use, either the Hobbs or FF, or can I use whichever value is higher for a given flight?

I'm not exactly trying to cheat the system, but if it's legal and fair...
 
Hobbs records the time the engine is running. Logging is supposed to be from the time the plane first moves "for the purpose of flight". Usually it's close enough. I don't know what FF does, presumably when it's moving?
 
The key isn’t so much what to use, but be able to explain why it’s the best answer. When does FF log, and why is it sometimes more and sometimes less than Hobbs time?

Then add them together for your logbook. ;)
 
I believe Ff goes back to first movement sensed... you are logging hours when you leave the hanger... might seem odd to the nosedragger but TW guys know you are flying that thing the moment you let go of the brakes to taxi...
 
Huckster79 said:
I believe Ff goes back to first movement sensed... you are logging hours when you leave the hanger... might seem odd to the nosedragger but TW guys know you are flying that thing the moment you let go of the brakes to taxi...
Click to expand...
How does FF know you’re leaving the hangar with the airplane and not the car?
 
MauleSkinner said:
How does FF know you’re leaving the hangar with the airplane and not the car?
Click to expand...

If the app is on it may not... for take off that’s ez... as it’s been off in car. At landing you may want to double check you hit “stop” on record. I had one 45 min flight where I landed n hauled butt putting her away to get to my boys basketball game an hour drive away... you should have seen the flight path it recorded for the “2 hour” flight it thought I had...

You can edit what it sends to log book...
 
Garmin pilot does that by threshold. You can configure to log when the speed is above 40 kts and 200 AGL start counting the flight time. You can also add a dedicated amount of taxi time to every log. I would assume FF have a similar feature.

I just use Hobbs.
 
Log whichever has the highest value.
 
Hobbs can run off of different things. Typically it is counting as soon as you start the plane. The Tach time is the engine time, and runs slower when the engine is slower. During taxiing it is much slower (i.e. less time counted) than Hobbs.



Sent from my SM-G973U using Tapatalk
 
Foreflight is always artificially high for me. I’ve got in the habit of recording engine start time and stop time and calculating my time. Often foreflight is still logging quite a few minutes after the plane is off for me.
 
Do you measure your oil change intervals with Hobbs, tach, watch/clock, app (FF, GP, WingX, etc) or by taste & smell?
 
sometimes I turn foreflight on at my house to do some preflighting and by the time I get to the airport it is already logged 1 hour of flight time.. in my opinion that feature is complete garbage
 
My advice: ditch FF logbook and use myflightbook. Much more seamless and capable(at least as of when i tried foreflight a year ago and hated it). This of course is not automatic and will need you to use the hobbs, but i think thats a more reliable method anyways.
 
The only time Hobbs is of questionable reliability is when some flight school set the Hobbs to start running with the master, instead of the engine. Otherwise, even the time you are starting and running that engine requires skill beyond just saying "prop clear."
 
Ryanb said:
Log whichever has the highest value.
Click to expand...
That's exactly what I was thinking. Is there any reason or regulation that says I cant do that? I know the whole "Pilot time that commences when an aircraft moves under its own power for the purpose of flight and ends when the aircraft comes to rest after landing" bit.
 
Michael A said:
[Myflightbook] is not automatic and will need you to use the hobbs, but i think thats a more reliable method anyways.
Click to expand...

Not quite true. You CAN enter the Hobbs times, or you can just press "Engine Start" and "Engine Stop" buttons and it will do the rest.
 
mryan75 said:
That's exactly what I was thinking. Is there any reason or regulation that says I cant do that? I know the whole "Pilot time that commences when an aircraft moves under its own power for the purpose of flight and ends when the aircraft comes to rest after landing" bit.
Click to expand...
So are you looking for an answer other than the correct one you gave?
 
mryan75 said:
That's exactly what I was thinking. Is there any reason or regulation that says I cant do that? I know the whole "Pilot time that commences when an aircraft moves under its own power for the purpose of flight and ends when the aircraft comes to rest after landing" bit.
Click to expand...

I'd say log what matches the regs. If you just want to log the higher number, then I can sell you a 2X stopwatch that will double your flight time.

Actually I should develop a "flight timer" app where you can set your multiplier to use! I'll make millions...
 
The FAA definition is as stated. The FAA is fairly lenient in allowing any reasonable approximation (tach time, hobbs time, time in motion from FF, or your GPS, etc...).

It is a misnomer to say that Hobbs time is determined by the engine running. It depends entirely on what electrical power source it is connected to. Some have it on the master, some on an oil pressure switch. In mine (and I believe later Bonanzas), it's on the gear switch. These planes don't have recording tach. The gear switch gives you the best approximation of "time in service" for maintenance of any of the schemes.
 
mryan75 said:
That's exactly what I was thinking. Is there any reason or regulation that says I cant do that? I know the whole "Pilot time that commences when an aircraft moves under its own power for the purpose of flight and ends when the aircraft comes to rest after landing" bit.
Click to expand...

flyingron said:
The FAA definition is as stated. The FAA is fairly lenient in allowing any reasonable approximation (tach time, hobbs time, time in motion from FF, or your GPS, etc...).
Click to expand...

@mryan75, what @flyingron says is true, with the caveat "as long as you're consistent about it." Using two different methods and logging whichever one gives you more time isn't what I think they would consider "consistent." And if they think you're cheating in any way, they can simply say that your logging was fraudulent, revoke your certificate, and make you start over from zero. Is that risk worth an extra tenth here and there?

Tantalum said:
sometimes I turn foreflight on at my house to do some preflighting and by the time I get to the airport it is already logged 1 hour of flight time.. in my opinion that feature is complete garbage
Click to expand...

I'm guessing you haven't used it in a while. I've had it record part of my drive (though I think it happened more going home from the airport in the kind of scenario @Huckster79 mentioned) but it's been a while since that happened. I think they are looking for the acceleration and climb from a runway these days, and when it detects the takeoff, it'll back up to when it started moving on the airport and that's taxi time. Not sure of the exact parameters but it seems to be working for me as long as I've stopped moving for a minute.
 
ircphoenix said:
My Hobbs was connected to my oil pressure switch. So when the engine came alive, so did the Hobbs. That's what I used to log flight time, so I probably cheated the FAA 3-4 minutes per flight by the engine being on but not moving... Getting ATIS and calling tower etc.

For maintenance purposes I used tach time.

I think that's generally how most people do it for both.
Click to expand...

If the propeller is turning, at least part of the aircraft is moving... And there have been FAA legal interpretations saying it's OK to use Hobbs time that way.

And yes, that's generally how it's done for logbook and MX, if the airplane is so equipped. My airplane has a maintenance Hobbs in the baggage compartment and a non-recording tach.
 
I look at my watch. If I forget, I multiply the tach by 1.2.

I knew an old salt that logged only currency requirements - didn't bother recording anything else. . .
 
flyingron said:
The FAA definition is as stated. The FAA is fairly lenient in allowing any reasonable approximation (tach time, hobbs time, time in motion from FF, or your GPS, etc...).

It is a misnomer to say that Hobbs time is determined by the engine running. It depends entirely on what electrical power source it is connected to. Some have it on the master, some on an oil pressure switch. In mine (and I believe later Bonanzas), it's on the gear switch. These planes don't have recording tach. The gear switch gives you the best approximation of "time in service" for maintenance of any of the schemes.
Click to expand...

Most rental operations have transitioned to the hobbs that is set to run off an oil pressure switch. The hobbs that run off other sources such as the master were too easy to circumvent; just turn off the master once the engine is started... At least for those more concerned with just flying and less concerned with the hours flown. Of course you get caught pretty quickly when you come back with an hour of tach time and no hobbs time but done "right" (in so far as there is a "right" way to cheat your rental operation and steal flight time) its very difficult to detect. If you own the plane and aren't renting it or otherwise billing for its use, there's little reason to move the hobbs power source except as a way to log more time (moving to a master switch hobbs or from a gear switch hobbs to something else).

Huckster79 said:
If the app is on it may not... for take off that’s ez... as it’s been off in car. At landing you may want to double check you hit “stop” on record. I had one 45 min flight where I landed n hauled butt putting her away to get to my boys basketball game an hour drive away... you should have seen the flight path it recorded for the “2 hour” flight it thought I had...

You can edit what it sends to log book...
Click to expand...

How do you edit the track log before sending it to foreflight's log book? I've had several flights that I had weird track logs as the result of this and have deleted the associated track log as a result. Wish I knew you could edit it instead of trashing it...
 
Sundancer said:
I look at my watch. If I forget, I multiply the tach by 1.2.

I knew an old salt that logged only currency requirements - didn't bother recording anything else. . .
Click to expand...

I think Part 91 have no obligation of recording flight time other than for currency requirements, so if you aren’t building time, some people don’t bother.
 
apr911 said:
Most rental operations have transitioned to the hobbs that is set to run off an oil pressure switch. The hobbs that run off other sources such as the master were too easy to circumvent; just turn off the master once the engine is started... At least for those more concerned with just flying and less concerned with the hours flown. Of course you get caught pretty quickly when you come back with an hour of tach time and no hobbs time but done "right" (in so far as there is a "right" way to cheat your rental operation and steal flight time) its very difficult to detect. If you own the plane and aren't renting it or otherwise billing for its use, there's little reason to move the hobbs power source except as a way to log more time (moving to a master switch hobbs or from a gear switch hobbs to something else).



How do you edit the track log before sending it to foreflight's log book? I've had several flights that I had weird track logs as the result of this and have deleted the associated track log as a result. Wish I knew you could edit it instead of trashing it...
Click to expand...

Couldn’t edit the trail log but u can edit the time...
 
You must log in or register to reply here.
Back
Top