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Logbook hours

Old 22nd Oct 2001, 03:48
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Question Logbook hours

How do people fill in their hours in the logbook? Do you use hours or minutes, or decimal?

I have always used decimal, in this format:

0.1 5mins 0.2 10mins 0.3 15mins 0.4 20mins 0.4 25mins 0.5 30mins
0.6 35mins 0.7 40mins 0.7 45mins 0.8 50mins 0.9 55mins 1.0 1hr

...and so on. This method I have always used, and have marked a clear table in the front of my logbook. Having just tried entering a logbook in hours and minutes I have only got about 15hours into my total hours and already the decimal total is out by 20mins, when converting say 16.3 to a hhmm total of 16:15.

This leads to a question. I have now amassed over 600 hours in decimal. When the total flying is less than 30mins it seems I am overcounting my hours, by when the total is more than 30mins per hour I am undercounting it, so it should even out over the hours.

No instructor I have flown with or anyone in the CAA has queried my method.

Can anyone clarify this? Should I carry on using the decimal figures, or run a correction to my total hours at the end of a page and then change my method?
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Old 22nd Oct 2001, 03:56
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I think decimal is normal (at least that's what I do ). Otherwise totaling the pages would be far more difficult to do. As you say, rounding errors tend to be small and cancel out anyway.
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Old 22nd Oct 2001, 15:05
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Courtman - your method is doomed to inaccuracy because you are not equating the correct proportion of an hour to the corect decimal. If you use 6 minute increments, every 6 minutes is 0.1 of an hour. If 6 minutes is too large an increment for your purposes, every 3 minutes is 0.05 of an hour. So you are likely, by rounding up or down to the nearest 0.05 to be much more accurate than the method you are using at present.

If periodically, you then need to convert the deimal recording to hours and minutes, of course the hours will be accurate anyway, and you simply multiple whatever aggregate fraction of an hour you happen to have, by 60, in order to record the correct number of logged minutes.
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Old 22nd Oct 2001, 15:34
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As has already been noted, .1 of an hour is six minutes, not five, therefore there is always a possibility of error in logging individual flights using this schema.

As to what's 'normal' - on my site the majority of english pilots log brakes-off to brakes-on in 5 minute increments, and log time elapsed in 5 minute increments. It's American pilots who tend to log decimals of hours for elapsed times - and most of them don't log brakes-off to brakes-on time at all.

As to the CAA's opinion. Well, one thing which prompted me to create the website was to improve my own accuracy of logging flights and summing the types of hours because I was worried about this. Since then loads of pilots have set up profiles, and many of them have quite large innacuracies in their data.

These are very experienced pilots, some of them professionals, many with 100s of hours, and they're logging P1s all over the place, they're logging dual time when they were P1, they're logging in command time when they were dual - all sorts of errors, causing some quite large discrepencies in their totals, and none of them has ever commented to me that the CAA ever even noticed.

I reckon that the examination they give to our treasured records is entirely cursory for most of the time - it's only when they're suspicious (or when they're researching accident causes), that they pay any real attention.....


Steve R
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Old 22nd Oct 2001, 17:06
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In the UK it's normal practice to log 5 minute increments. Civil pilots log chock to chock, whilst military pilots log take-off to landing. [Used to really p&*^ us of at BDN that when doing a ground handling trial.] The exception is glider pilots, who have too many 2 or 3 minute flights to make 5 minute increments sensible.

Frankly, I think that if you've got enough hours to make a significant error, does it really matter if you have 150 or 160 hrs P1 (or 2000 or 2100) in a particular type? I try to keep my logbook as accurate as possible (and incidentally, most scientific calculators will add up hours and minutes) but don't lose any sleep over it.

G
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Old 29th Oct 2001, 09:08
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I have always logged in decimal, fits in very nicely with the Hobbs meter as well.

I normally deduct 0.3 from the total for mucking about on the ground and log this is the actual.

Julian.
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Old 29th Oct 2001, 11:28
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It seems to me that only Americans and the Army use decimal hours. The rest of us are able to add up minutes correctly - or use the DMS>DD function on calculators to add up the total on a logbook page.

How many clocks have decimal minutes?
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Old 29th Oct 2001, 12:13
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How many clocks have decimal minutes?
Well the Hobbs meter, for one
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Old 29th Oct 2001, 23:46
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In my logbook I use Hours and Minutes, Eg. having flown 1 hour 5 minutes, brakes off to brakes on, this would be entered 1:05 and so on. I recently got my PPL and this method was not questioned. If you are happy with the method you are using stay with it, as changing to another method half way through may cause confusion to anyone who has not looked at your logbook.
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Old 30th Oct 2001, 13:27
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Hey BEagle

Better add the Kiwis to the list of fools that account for their hours in decimals, or at least this fool was taught that way...

Actually, individual flights are accounted for in decimals, but each page is totalled up in hours and minutes....perhaps I was not listening in school on that first day?
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Old 30th Oct 2001, 16:48
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I've always used hours and minutes, rounded to 5 minute blocks, chock to chock. Seems to me the logical way to record data which is based on actual clock-time which is universally in minutes.

My practice is to book actual chock to chock for each flight, except for those occasions at an international airport (when the hold for IFR movements would sometimes be better measured with a calendar...) then its t/off and land each +5 mins ie flight time + 10 mins.

Adding up minutes and hours on the ground in a logbook shouldn't be a problem, after all ETAs etc are in hours/minutes, not decimals, and the brain is frequently multi-tasking at the time!

Hobbs meter is ... a meter, which stops and starts with usage, and can record whatever units its calibrated for. A clock is "kept in motion" (OED) and I haven't seen a decimal one yet.

Julian, at least there's no VAT, whether minutes or decimal-hours!

SlipSlider
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Old 30th Oct 2001, 17:13
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In private flying of which this is a forum, the hobbs starts on engine start and stops at engine stops.

It is prudent for hour building to log in 6 minute intervals and get more for your money.
 
Old 30th Oct 2001, 18:37
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I have always used whole hours and then mins (eg 1:15 being 1 hour, 15mins). I find this easiest, but as someone has said before, if you are happy with the way you do it, why change? I don't think the CAA care which way you use.
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Old 30th Oct 2001, 20:15
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Slipslider - Quite right mate, although keep it quite or HMG may try and tax that as well to pay for Johnny Two Jags running expenses
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Old 30th Oct 2001, 22:08
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Wink

Actually, individual flights are accounted for in decimals, but each page is totalled up in hours and minutes....perhaps I was not listening in school on that first day?
Forgive me if this comes off as critical:

this seems a bit backwards--the problem with logging decimal is the inaccuracy when converting from clock time*. The problem with using minutes is that they are harder to add and more subject to errors in the adding.

It seems you've got the worst of both and introduce two possible errors-one on the conversion to decimal and one on the conversion back. Once the hours are in decimal I see no reason to convert back to minutes-after all there are no requirements that hinge on the number of minures you have ["you need 3 hours and 11 minutes of night flying to get this rating"]. All requirements that I know of are in terms of whole hours, so might as well keep it in decimal.

As to logging entirely in minures--that makes sense to me too.


*not a problem here in the states where we log hobbs time

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Old 2nd Nov 2001, 02:55
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Ah the penny has dropped!
*not a problem here in the states where we log hobbs time
So now my question is - why doesn't everyone log Hobbs time? Seems far more sensible, with the added benefit of being decimal
Hobbs... a meter, which stops and starts with usage
Surely that's the whole point? The fact that the meter does just that means that there can be no argument about what is logged, for both pilot and maintenance.

[ 01 November 2001: Message edited by: sanjosebaz ]
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Old 2nd Nov 2001, 10:25
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sanjosebaz

What?????? log decimal time???? We Brits have been around for thousands of years and I can tell you that we never logged decimal time back in the 1600s when you American guys were just colonials!

Preposterous!
 
Old 2nd Nov 2001, 10:56
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You may NOT log 'Hobbs' time in a UK personal logbook! Whereas the hire of the aircraft may be charged by using 'Hobbs time', the flight time in a personal logbook MUST be recorded as 'from the time the aircraft first moves under its own power for the intention of taking off (i.e. 'chocks away') to the time of completion of the normal taxying process after landing (i.e. 'chocks under')'. Anyone logging 'Hobbs time' has not recorded their flight time in the required manner.

Decimal time - OK for thickos who never learned how to add up hours and minutes perhaps, but for the rest of us it has no relevance.

[ 02 November 2001: Message edited by: BEagle ]
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Old 2nd Nov 2001, 11:57
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I used to be syndicated on an aircraft with a bit of a starting problem (once it started it was always fine). That's where I discovered that on failed starts a Hobbs can jump forward. My record was 0.7hrs without leaving the chocks.

Needless to say, I had to pay by the Hobbs reading, but my personal logbook could only log chock to chock.

G

[ 02 November 2001: Message edited by: Genghis the Engineer ]
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Old 2nd Nov 2001, 13:43
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Progress to anything beyond a piston and suddenly you won't have a Hobbs any more. Mind you you will have a clock with good old-fashioned hours and minutes.

regards
wizzy
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