Hobbs/VDO, tach time and airswitch?
“Pretty much what ever suits you” might be OK for charging regimes, but care must be taken to comply with the law.
There’s a legal requirement to record an aircraft’s time in service in the MR or its equivalent. There is a definition of time in service. There is no latitude to do anything other than comply with the requirement.
There’s a legal requirement for a pilot to record flight time in the pilot’s logbook. There is a definition of flight time. There is no latitude other than comply with the requirement.
There’s a legal requirement to record an aircraft’s time in service in the MR or its equivalent. There is a definition of time in service. There is no latitude to do anything other than comply with the requirement.
There’s a legal requirement for a pilot to record flight time in the pilot’s logbook. There is a definition of flight time. There is no latitude other than comply with the requirement.
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100% agree Lead Balloon.
The sticky point is the many and varied means by which TIS is ascertained.
I'm guessing that some time in the distant past clock time and tacho time were not too different. Not the case now.
The sticky point is the many and varied means by which TIS is ascertained.
I'm guessing that some time in the distant past clock time and tacho time were not too different. Not the case now.
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Thank you all for these very informative answers. This now better explains how flight schools and operators turn their profit. From daily meter sheets for various aircraft, I observe that the maintenance time is on average 0.2 to 0.4 hour below engine time, which is a sizeable fraction when the latter only average 0.9 to 1.3 hours. That's at a fairly large airport where taxi distances and waiting times (I'm looking at you, HOLD SHORT OF RWY XY) can occasionally be long, esp. when circuits are busy.
Whilst the practice of charging on engine time alone makes it easier to understand how one is being billed at first, this remains of somewhat questionable ethics if the true cost incurred will only ever be that of 1-3 litres of Avgas.
Alas, I find this just plain counterproductive and almost an incentive to want to rush through run-ups and to taxi at 25 kts.
Whilst the practice of charging on engine time alone makes it easier to understand how one is being billed at first, this remains of somewhat questionable ethics if the true cost incurred will only ever be that of 1-3 litres of Avgas.
Alas, I find this just plain counterproductive and almost an incentive to want to rush through run-ups and to taxi at 25 kts.
Money ‘in’ still has to equal or exceed money ‘out’ in order for an operator to be viable.
You could try to insist that you’re charged on the basis of time in service - wheels off to wheels on - rather than e.g. battery on to battery off. All that would happen is that the hourly rate would be increased accordingly.
Remember, you’re still in command or dual while operating the aircraft on the ground, and that’s aeronautical experience that goes into your logbook. Part of the learning experience is to resist the urge to taxi at 25 knots and rush through run-ups, to save $50. If you have an accident as a consequence, you’ll be a lot further in the hole than $50.
You could try to insist that you’re charged on the basis of time in service - wheels off to wheels on - rather than e.g. battery on to battery off. All that would happen is that the hourly rate would be increased accordingly.
Remember, you’re still in command or dual while operating the aircraft on the ground, and that’s aeronautical experience that goes into your logbook. Part of the learning experience is to resist the urge to taxi at 25 knots and rush through run-ups, to save $50. If you have an accident as a consequence, you’ll be a lot further in the hole than $50.
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Remember, you’re still in command or dual while operating the aircraft on the ground, and that’s aeronautical experience that goes into your logbook. Part of the learning experience is to resist the urge to taxi at 25 knots and rush through run-ups, to save $50. If you have an accident as a consequence, you’ll be a lot further in the hole than $50.
Folks,
With our "ever changing" rules, two of the things that have been constant are the definitions of (loosely described) "Chock to Chock" for logging pilot time, and "time in service" for maintenance purposes, wheels off to wheels on.
Thankfully, these definitions, in my experience, are universal.
Lead Balloon has spelled it out in legal terms.
If you are being told otherwise by your instructor/CFI/LAME/FOI/AWI/whatever, they are airing their ignorance, the correct aeronautical term being: "talking bollocks".
Commercial organisations can arrange their billing on whatever basis they choose, it doesn't have to be related to Flight Time or Time in Service, or tacho time, dreamtime or whatever.
And confirming, VDO and Hobbs a the name of instrument makers, as are Smiths, Stewart Warner (for the older brigade) and the dreaded Lucas.
Tootle pip!!
PS: Many "tachos" that are part of a rev counter only record "time" at the same rates as your watch at a reference RPM, if you'r using higher RPM the recorded time will be more than elapsed/chronological time, at low RPM, they will record less than elapsed time.
With our "ever changing" rules, two of the things that have been constant are the definitions of (loosely described) "Chock to Chock" for logging pilot time, and "time in service" for maintenance purposes, wheels off to wheels on.
Thankfully, these definitions, in my experience, are universal.
Lead Balloon has spelled it out in legal terms.
If you are being told otherwise by your instructor/CFI/LAME/FOI/AWI/whatever, they are airing their ignorance, the correct aeronautical term being: "talking bollocks".
Commercial organisations can arrange their billing on whatever basis they choose, it doesn't have to be related to Flight Time or Time in Service, or tacho time, dreamtime or whatever.
And confirming, VDO and Hobbs a the name of instrument makers, as are Smiths, Stewart Warner (for the older brigade) and the dreaded Lucas.
Tootle pip!!
PS: Many "tachos" that are part of a rev counter only record "time" at the same rates as your watch at a reference RPM, if you'r using higher RPM the recorded time will be more than elapsed/chronological time, at low RPM, they will record less than elapsed time.
Last edited by LeadSled; 13th Apr 2018 at 14:03. Reason: typo
Oki, if you want to evaluate the market more accurately, you need to ask for the basis on which you will be charged for aircraft hours.
Airswitch = time in the air +/- a bit.
Tacho = what the tacho reads. Remember, for a standard steam driven tacho 1 hour tacho time only equals 1 hour of real time at a specified RPM (I think it’s 2,350 on most, but you can googlerate that to find out). So, keep your RPMs down while taxiing! 15 minutes of taxi time at low RPMs does not equal 15 minutes counted on the tacho.
Hobbs/VDO = meaningless unless they tell you and you can confirm what switches it on and off. If it’s connected to the battery/master switch, that’s the method that results in the longest time charged.
Don’t forget to ask for the fine print about fuel costs. If you rent the aircraft ‘wet’, does that include whatever price fuel costs wherever you go? Even at William Creek or Forrest?
Don’t forget to ask for the fine print about terminal navigation charges, landing and parking fees and all the other people who want to get their hands in your pocket.
Don’t forget to ask what happens if the aircraft goes unserviceable at e.g. Leigh Creek.
Airswitch = time in the air +/- a bit.
Tacho = what the tacho reads. Remember, for a standard steam driven tacho 1 hour tacho time only equals 1 hour of real time at a specified RPM (I think it’s 2,350 on most, but you can googlerate that to find out). So, keep your RPMs down while taxiing! 15 minutes of taxi time at low RPMs does not equal 15 minutes counted on the tacho.
Hobbs/VDO = meaningless unless they tell you and you can confirm what switches it on and off. If it’s connected to the battery/master switch, that’s the method that results in the longest time charged.
Don’t forget to ask for the fine print about fuel costs. If you rent the aircraft ‘wet’, does that include whatever price fuel costs wherever you go? Even at William Creek or Forrest?
Don’t forget to ask for the fine print about terminal navigation charges, landing and parking fees and all the other people who want to get their hands in your pocket.
Don’t forget to ask what happens if the aircraft goes unserviceable at e.g. Leigh Creek.
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Awesome, as always, this forum is a great place to ask questions. Many thanks to you all.
How dare those evil flying schools try to make a dollar! We should be doing it for the love of it and living under a bridge!
As an example, an aircraft hired on VDO will do about 115 revenue hours for every 100 hours in service. Therefore the gross margins are calculated on 115 hours/100 hourly. So if the hirer wants to rent it on tacho, no worries, but you will pay 15% more per hour.
If you want to buy fuel in Forrest, you pay the difference between that and the local rate so a hire wet or dry won't make any difference.
As for the economics remember that if the operator is on a 15% margin, that's just nine minutes in every hour that is covering fixed costs and maybe evilly making a profit. Agreed this is the sort of thing that CPL students should be aware of. So run an aviation organisation for 20 years and then get back to me if you have a more clever way.
But remember for example things happen that aren't budgeted for. EG The piece of FOD that caused a puncture to one of my aircraft recently ended up costing over $1000 by the time you have paid for recovery, new tube and tyre, labour, down time. That's just when it happens at home base with a handy shop that sells tyres and a handy engineer to fix it. So the evil flying schools have to build that sort of thing into the costs. Unethical to have some bucks set aside for this sort of thing? Making the unfortunate hirer who landed on someone else's FOD pay for the flat tyre would have been unethical.
As an example, an aircraft hired on VDO will do about 115 revenue hours for every 100 hours in service. Therefore the gross margins are calculated on 115 hours/100 hourly. So if the hirer wants to rent it on tacho, no worries, but you will pay 15% more per hour.
If you want to buy fuel in Forrest, you pay the difference between that and the local rate so a hire wet or dry won't make any difference.
As for the economics remember that if the operator is on a 15% margin, that's just nine minutes in every hour that is covering fixed costs and maybe evilly making a profit. Agreed this is the sort of thing that CPL students should be aware of. So run an aviation organisation for 20 years and then get back to me if you have a more clever way.
But remember for example things happen that aren't budgeted for. EG The piece of FOD that caused a puncture to one of my aircraft recently ended up costing over $1000 by the time you have paid for recovery, new tube and tyre, labour, down time. That's just when it happens at home base with a handy shop that sells tyres and a handy engineer to fix it. So the evil flying schools have to build that sort of thing into the costs. Unethical to have some bucks set aside for this sort of thing? Making the unfortunate hirer who landed on someone else's FOD pay for the flat tyre would have been unethical.
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The sole advantage to VDO is that it allows you to advertise a lower rate.
This is lost the first time the hirer sits for 15 minutes at the holding point waiting for a break in traffic to take off and works out they spent $70+ to just sit and watch aircraft.
That is a BIG disincentive to coming back and doing it again. I would much rather pay a higher rate for air time, and not have the dollars ticking over while waiting on the ground. Especially if the operators costs are primarily based on airswitch.
This is lost the first time the hirer sits for 15 minutes at the holding point waiting for a break in traffic to take off and works out they spent $70+ to just sit and watch aircraft.
That is a BIG disincentive to coming back and doing it again. I would much rather pay a higher rate for air time, and not have the dollars ticking over while waiting on the ground. Especially if the operators costs are primarily based on airswitch.
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and works out they spent $70+ to just sit and watch aircraft
That includes listening and copying down an ATIS then studying its ramifications before engine start rather than with engines running before taxiing.
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Maintenance time is calculated only of the m/r or equivalent doc period. What time you or not is up to you. This dose not mean you may go against the requirements of any regulations.
Wheels off to wheels on is actual maintenance time per the regulations.
Flight schools are free to charge what ever they like and calculate it how they wish.
Maintenance on the ground ie engines runs are not part of any time that is to be recorded on the m/r ie it dose not form pard of any additional hours to be recorded against tbo time.
Wheels off to wheels on is actual maintenance time per the regulations.
Flight schools are free to charge what ever they like and calculate it how they wish.
Maintenance on the ground ie engines runs are not part of any time that is to be recorded on the m/r ie it dose not form pard of any additional hours to be recorded against tbo time.
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So does that mean the hours on the tacho instrument will never be equal to the total hours on the engine once any maintenance ground runs have been done?
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How dare those evil flying schools try to make a dollar! We should be doing it for the love of it and living under a bridge!
As an example, an aircraft hired on VDO will do about 115 revenue hours for every 100 hours in service. Therefore the gross margins are calculated on 115 hours/100 hourly. So if the hirer wants to rent it on tacho, no worries, but you will pay 15% more per hour.
If you want to buy fuel in Forrest, you pay the difference between that and the local rate so a hire wet or dry won't make any difference.
As for the economics remember that if the operator is on a 15% margin, that's just nine minutes in every hour that is covering fixed costs and maybe evilly making a profit. Agreed this is the sort of thing that CPL students should be aware of. So run an aviation organisation for 20 years and then get back to me if you have a more clever way.
As an example, an aircraft hired on VDO will do about 115 revenue hours for every 100 hours in service. Therefore the gross margins are calculated on 115 hours/100 hourly. So if the hirer wants to rent it on tacho, no worries, but you will pay 15% more per hour.
If you want to buy fuel in Forrest, you pay the difference between that and the local rate so a hire wet or dry won't make any difference.
As for the economics remember that if the operator is on a 15% margin, that's just nine minutes in every hour that is covering fixed costs and maybe evilly making a profit. Agreed this is the sort of thing that CPL students should be aware of. So run an aviation organisation for 20 years and then get back to me if you have a more clever way.
But charging at a fixed rate on VDO is skewed and does not generally benefit flight training in my opinion.
As you seem well versed in the mechanics flight school operations, here's an honest question. How about charging for lessons as follows:
Lesson bill = lesson base price that covers aircraft fixed costs (insurance, parking, landing fees, etc.)
+ fuel used ╳ fuel (daily/weekly) rate
+ oil used ╳ oil cost+ tacho/airswitch time ╳ hire rate which will cover variable aircraft costs such as maintenance, engine overhaul, etc.
+ VDO time ╳ instructor rate in flight
+ pre- and post-flight briefing time ╳ instructor rate on ground
where all the rates are transparent and worked out so that, in the end, a margin deemed adequate to run the business is yielded.
+ oil used ╳ oil cost+ tacho/airswitch time ╳ hire rate which will cover variable aircraft costs such as maintenance, engine overhaul, etc.
+ VDO time ╳ instructor rate in flight
+ pre- and post-flight briefing time ╳ instructor rate on ground
where all the rates are transparent and worked out so that, in the end, a margin deemed adequate to run the business is yielded.
Absolutely nothing wrong with flight schools not being charities and actually thumbs up to those that are profitable in this day and age.
But charging at a fixed rate on VDO is skewed and does not generally benefit flight training in my opinion.
As you seem well versed in the mechanics flight school operations, here's an honest question. How about charging for lessons as follows:
Lesson bill = lesson base price that covers aircraft fixed costs (insurance, parking, landing fees, etc.)
But charging at a fixed rate on VDO is skewed and does not generally benefit flight training in my opinion.
As you seem well versed in the mechanics flight school operations, here's an honest question. How about charging for lessons as follows:
Lesson bill = lesson base price that covers aircraft fixed costs (insurance, parking, landing fees, etc.)
+ fuel used ╳ fuel (daily/weekly) rate
+ oil used ╳ oil cost+ tacho/airswitch time ╳ hire rate which will cover variable aircraft costs such as maintenance, engine overhaul, etc.
+ VDO time ╳ instructor rate in flight
+ pre- and post-flight briefing time ╳ instructor rate on ground
where all the rates are transparent and worked out so that, in the end, a margin deemed adequate to run the business is yielded.
+ oil used ╳ oil cost+ tacho/airswitch time ╳ hire rate which will cover variable aircraft costs such as maintenance, engine overhaul, etc.
+ VDO time ╳ instructor rate in flight
+ pre- and post-flight briefing time ╳ instructor rate on ground
where all the rates are transparent and worked out so that, in the end, a margin deemed adequate to run the business is yielded.
In aviation, some are both.
Thank you for being so patronising, the formula I have is working fine. When you have trialled yours at your own flying school for ten years please get back to us all here and let us know how it's going.
Lesson bill = lesson base price that covers aircraft fixed costs (insurance, parking, landing fees, etc.)
+ fuel used ╳ fuel (daily/weekly) rate
+ oil used ╳ oil cost+ tacho/airswitch time ╳ hire rate which will cover variable aircraft costs such as maintenance, engine overhaul, etc.
+ VDO time ╳ instructor rate in flight
+ pre- and post-flight briefing time ╳ instructor rate on ground
where all the rates are transparent and worked out so that, in the end, a margin deemed adequate to run the business is yielded.
+ oil used ╳ oil cost+ tacho/airswitch time ╳ hire rate which will cover variable aircraft costs such as maintenance, engine overhaul, etc.
+ VDO time ╳ instructor rate in flight
+ pre- and post-flight briefing time ╳ instructor rate on ground
where all the rates are transparent and worked out so that, in the end, a margin deemed adequate to run the business is yielded.
I run a flying school, have done on and off for years, decades even. How about we charge VDO. It starts when the oil hits the switch and ends when the engine stops. For that you get me sitting next to you, a heap of free time briefing and debriefing and the use of my facilities, can't come much simpler than that.
Plus I charge flight test fees and flight review fees. Simple really, nothing hidden. Feel free to bring your own aircraft even.
i thought it would be quite simple. Maintainance wise, airswitch. Business wise tacho switch or whatever you call it from start up till shut down. Why complicate it?
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The mr ttis for the aircraft dose not change in the top of the mr. Its transfered from the previous mr. So zero change.
So sometimes an air stwich is used so you note that on the mr.
Ie
Ttis
5500/679 airswtich vdo etc
This means if the vdo has been changed its noted with the new hours
But maintenance can also be noted with both figures but must use ttis.
So for example in the due column
Ad/c175/ 4a5 ttis5550 or 729as or 04/dec/18.
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Before coming up with a formula try learning the difference between fixed and variable costs.
In aviation, some are both.
Thank you for being so patronising, the formula I have is working fine. When you have trialled yours at your own flying school for ten years please get back to us all here and let us know how it's going.
In aviation, some are both.
Thank you for being so patronising, the formula I have is working fine. When you have trialled yours at your own flying school for ten years please get back to us all here and let us know how it's going.