Airplane log times vs pilot log times

[Oldguystrtn2fly]

I have been taught that Hobbs (or tach time if you have no Hobbs) , is flight time. Time up to time down is air time. Flight time is the pilot logged time. So 1.0 Hobbs ,or flight time, equals 1.0 PIc time, or dual etc in the pilot log book, assuming he keeps one. If the same flight yields an airtime of 0.8, all the aircraft times go up by 0.8, so 0.8 more for airframe, engine and propeller times.

Do I have this correct ? I was recently told elsewhere that airframe was equal to tach time but that has me scratching my head.

Thanks all for any clarification. Also this would be for a private aircraft.

[dialdriver]

I have been taught that Hobbs (or tach time if you have no Hobbs) , is flight time. Time up to time down is air time. Flight time is the pilot logged time. So 1.0 Hobbs ,or flight time, equals 1.0 PIc time, or dual etc in the pilot log book, assuming he keeps one. If the same flight yields an airtime of 0.8, all the aircraft times go up by 0.8, so 0.8 more for airframe, engine and propeller times.

Do I have this correct ? I was recently told elsewhere that airframe was equal to tach time but that has me scratching my head.

Thanks all for any clarification. Also this would be for a private aircraft.

Flight time starts when the aircraft starts to taxi for the purpose of flight until it taxis to a stop after the flight. Air time starts when you leave the ground until you land. Hobbs and tach are not a legal reference for log book purposes. See the CARs.

[Chris M]

Yep, that.

In small planes Hobbs time is generally very close to your flight time and so is generally used for personal logbooks since we generally get a move on within a minute or two of starting, however, this is not a technically correct way to record time. If you were to start up and sit for 10 minutes getting clearances and waiting to taxi you are not entitled to put that .2 in your logbook.

Tach time is useless for most folks. Some clubs use it for billing as it is thought to better represent the usage of the aircraft, but otherwise it has no legal use.

[Oldguystrtn2fly]

And in the tech logs. Airtime for engine, frame and prop?

[dialdriver]

And in the tech logs. Airtime for engine, frame and prop?

Correct.

[Oldguystrtn2fly]

Ok, I pretty much do this correctly then. I use tach for flight time I guess but I am a5 a uncontrolled airport so it likely has little consequence. I will start to track taxi start stop and see if it differs much.

[photofly]

If you were to start up and sit for 10 minutes getting clearances and waiting to taxi you are not entitled to put that .2 in your logbook.

If you roll forward six inches before you sit for ten minutes, then sure you are.

Tach time is useless for most folks. Some clubs use it for billing as it is thought to better represent the usage of the aircraft, but otherwise it has no legal use.

Tach time depends on RPM, which isn’t helpful.

[Schooner69A]

Without the benefit of higher education, my peers and I had to resort to something simple.

Since the middle of the last century, I've used time up and down as air time. Add another ten minutes (or point 2) for flight time.

Worked military, corporate, TC; now private.

I don't even note exact times any more. At the end of the trip, Mr GPS tells me my time in the air and manufacture up/down times to suit.

[Pratt X 3]

Tach time used to be the standard for airframe time. The US still seems to use that for that purpose. Tach hour meters are set up to correspond to the typical cruise RPM setting equaling an hour in real life (i.e 2300 RPM tachometer will read 1 hour at that RPM; less than an hour at higher settings and more than an hour at lower settings).

As for time to be used in tech logs:
625.93 Technical Records - General
(1) Pursuant to Item 4 of Schedule I to subpart 605, persons calculating times between maintenance activities need only consider air time (i.e. the intervals from the moment an aircraft leaves the ground until it touches the ground at the end of the flight); the air time specified must be the actual air time, and not arrived at by calculation from the total flight time.
(amended 2008/12/30)
http://www.tc.gc.ca/eng/civilaviation/r ... htm#625_93

[AirFrame]

It's important to note that tach time and Hobbs time aren't the same... As PrattX3 mentions, the tach is set to record time at an average cruise RPM. What I didn't see mentioned anywhere is that the Hobbs is electric and usually connected to the Master or an oil pressure switch... So if the engine is running, it's counting.

My aircraft didn't come with a "Hobbs" meter, just the Tach. After a number of flights where I kept detailed notes, I determined that the Tach did indeed correlate very accurately with Air Time, so I use it for recording times in my and the aircraft's log book as air time. I add .1 or .2 to the flight for "flight time" depending on how much time I spent f*rting around before takeoff or after landing.

[Zaibatsu]

A hobbs meter runs off of aircraft power and an oil pressure switch in most light aircraft. Some flight schools bypass the oil pressure switch and have it run off the battery master as a deterrent to leaving the master on. Though they might charge you for the time, it certainly doesn't count as flight time.

Flight time starts at the first movement of the aircraft for the purpose of taking off. I don't think rolling forward and then setting up avionics, getting clearance, etc is within the spirit of that definition.

But in the real world, nobody is going to know, and nobody is going to care. 2 hours of accumulated 172 or Dutchess time means sweet f all in the grand scheme of things.

[Oldguystrtn2fly]

It's important to note that tach time and Hobbs time aren't the same... As PrattX3 mentions, the tach is set to record time at an average cruise RPM. What I didn't see mentioned anywhere is that the Hobbs is electric and usually connected to the Master or an oil pressure switch... So if the engine is running, it's counting.

My aircraft didn't come with a "Hobbs" meter, just the Tach. After a number of flights where I kept detailed notes, I determined that the Tach did indeed correlate very accurately with Air Time, so I use it for recording times in my and the aircraft's log book as air time. I add .1 or .2 to the flight for "flight time" depending on how much time I spent f*rting around before takeoff or after landing.

Are you saying you use airtime for your pilot log book? And not flight time?

[digits_]

I don't think rolling forward and then setting up avionics, getting clearance, etc is within the spirit of that definition.

I find the definition/regulation extremely vague. What IS the spirit of the definition? Measuring how long a pilot spent in the plane training/working his skills? Measuring how long an airplane has increased risk of having an accident (since it isn't parked safely in a hangar)? Historically grown so it corresponds to the departure/arrival times on boards in terminals? I have no clue.

If setting up radios isn't part of flight time, is doing a run up? Is holding while waiting for other traffice to land? Is taxiing via detour to allow other planes to taxi more efficient?
Taxiing to a deice bay and getting deiced is not part of flight time, yet this is just one of the delays people can get when going fying.
What if you taxi the plane over to the mechanic, with your intention of getting it fixed to fly the next day? I think it's safe to say everyone of us gets in planes with the intention of eventually taking off.

A very interesting grey area.

[ahramin]

Oldguy, I don't see how Airframe could have been more clear. For his pilot logbook he is using his estimated air time plus .1 or .2 depending on his estimate of time taxiing. Obviously air time + 0.1 is not = air time.

For your original question, as others have said it's very simple:

1. Personal logbook time is flight time. Flight time has a complicated definition so everyone just uses the time the engine is running. TC knows about this and has no problem with it.
2. Aircraft total time is air time. Air time is from takeoff to landing.
3. Tach time isn't anything.
4. Many pilots find it too much effort to record start takeoff land and stop time so they just guess via various methodology and put that in the books.

[airway]

1. Personal logbook time is flight time. Flight time has a complicated definition so everyone just uses the time the engine is running. TC knows about this and has no problem with it.
2. Aircraft total time is air time. Air time is from takeoff to landing.
3. Tach time isn't anything.
4. Many pilots find it too much effort to record start takeoff land and stop time so they just guess via various methodology and put that in the books.

Not everyone. I know from personal experience that some flight schools in Canada, Jazz, Air Canada, and I would bet most major airlines in Canada, record and use the the 4 times (1st movement, takeoff, landing, and stop taxi) required to comply with TC's definition of air/flight times.

I agree with everything else you said here ahramin, particularly #4

From the AIM:

4.1
Air Time is the period of time commencing when the aircraft leaves the supporting surface and terminating when it touches the supporting surface at the next point of landing.

Flight Time is the total time from the moment an aircraft first moves under its own power for the purpose of taking off until the moment it comes to rest at the end of the flight. This should be recorded in all Pilot Log Books.

NOTE:
Air Time and Flight Time should be recorded to the nearest 5 minutes, or to the nearest 6 minutes when using the decimal system as follows:
0 to 02 = .0
03 to 08 = .1
09 to 14 = .2
15 to 20 = .3
21 to 26 = .4
27 to 32 = .5
33 to 38 = .6
39 to 44 = .7
45 to 50 = .8
51 to 56 = .9
57 to 60 = 1.0

No need to convert to the decimal system if you don't want to.

The definition of flight time is going to be changed. They are going to delete the ""under its own power" part to allow flight time to start at the beginning of pushback. Many airlines have automated systems that start and stop the recording of flight time at park brake release to park brake set at the gate.

[digits_]

The definition of flight time is going to be changed. They are going to delete the ""under its own power" part to allow flight time to start at the beginning of pushback. Many airlines have automated systems that start and stop the recording of flight time at park brake release to park brake set at the gate.

So you can start logging the time as soon as you start pulling your 172 out of the hangar?

[AuxBatOn]

I don't think rolling forward and then setting up avionics, getting clearance, etc is within the spirit of that definition.

I find the definition/regulation extremely vague. What IS the spirit of the definition? Measuring how long a pilot spent in the plane training/working his skills? Measuring how long an airplane has increased risk of having an accident (since it isn't parked safely in a hangar)? Historically grown so it corresponds to the departure/arrival times on boards in terminals? I have no clue.

If setting up radios isn't part of flight time, is doing a run up? Is holding while waiting for other traffice to land? Is taxiing via detour to allow other planes to taxi more efficient?
Taxiing to a deice bay and getting deiced is not part of flight time, yet this is just one of the delays people can get when going fying.
What if you taxi the plane over to the mechanic, with your intention of getting it fixed to fly the next day? I think it's safe to say everyone of us gets in planes with the intention of eventually taking off.

A very interesting grey area.

Not a grey area at all...

"flight time means the time from the moment an aircraft first moves under its own power for the purpose of taking off until the moment it comes to rest at the end of the flight;"

The first time you taxi out with the intent to takeoff, you can start logging it. If you are going through de-icing, this counts as well.

[digits_]

Not a grey area at all...

"flight time means the time from the moment an aircraft first moves under its own power for the purpose of taking off until the moment it comes to rest at the end of the flight;"

The first time you taxi out with the intent to takeoff, you can start logging it. If you are going through de-icing, this counts as well.

The last 2 companies I worked at, had it in their transport approved COM that time spent travelling to a deicing bay was not included in flight time. Personally, I think that's ridiculous.

[airway]

The last 2 companies I worked at, had it in their transport approved COM that time spent travelling to a deicing bay was not included in flight time. Personally, I think that's ridiculous.

This is absolutely ridiculous. By this logic, time spent traveling to the runup bay for a runup should also not be included in flight time.

Or how about the time spent traveling to the button of the runway, because you had to stop momentarily to let another aircraft clear the runway?

[AuxBatOn]

Yup, it all counts.