flight hours vs hobbs hours and repairs ?
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flight hours vs hobbs hours and repairs ?
I just would like to hear some more opinions on the following facts I heard yesterday from a friend, who runs a flight school and charter business.
He changed his business from charging per Hobbs hours to real flight time about a year ago and now claims that engine repair costs for the otherwise unchanged fleet has gone down 30%. He is running 172, 182, PA24 and PA28 with about one third in training and two third in charter.
First reason in my mind was that running on Hobbs tend to let people hurry to take off with less warm up, but can this effect be such big?
He changed his business from charging per Hobbs hours to real flight time about a year ago and now claims that engine repair costs for the otherwise unchanged fleet has gone down 30%. He is running 172, 182, PA24 and PA28 with about one third in training and two third in charter.
First reason in my mind was that running on Hobbs tend to let people hurry to take off with less warm up, but can this effect be such big?
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First reason in my mind was that running on Hobbs tend to let people hurry to take off with less warm up, but can this effect be such big?
It is also a very unfair way of charging customers IMHO. as hobbs times are rarely ever the same as the required pilots logging time ie Brakes off-Brakes on.
Usually people are overcharged. and by the same token if logging your airframe/engine hours using it you are probably doing more maintenance than needed over the life of an engine.
I have seen people being stuck at the hold because of some officias **** of a FISO wouldn't give the "Clearance" for TO and you can end up just sitting on the ground clocking up unnecessary hours, because engine logs as are usually (Except Rotax?) TO/Touchdown
Last edited by PA28181; 29th Jan 2015 at 16:05.
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Just to jump in and ask a daft question, if you're charged "Brakes-off to Brakes on" is that the moment the a/c moves under it's own power (leaving the apron) to the moment you stop back in it's parking place on the apron?
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The only recent time I've flown rental, the Hobbs was used, as the tach did not have an hour meter. They charged you for the Hobbs time, less 0.3 hours, as they knew that that would the proper amount of warm up time. It was a Schwiezer helicopter, so it did not have brakes.
To be fair from a fuel burn and maintenance perspective, the significant "cost" to operate the plane starts when you apply takeoff power, and ends when you taxi off the runway. Charging for time other than that is being greedy.
To be fair from a fuel burn and maintenance perspective, the significant "cost" to operate the plane starts when you apply takeoff power, and ends when you taxi off the runway. Charging for time other than that is being greedy.
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I recently hired for the first time in years and was astounded to find that the club was charging tacho time + 0.2 hours per flight. This was allegedly because the tacho under counted time during ground running (which it does of course, but, as has already been pointed out, ground time doesn't cost much). This seems to me to be a way of disguising the charges so that hourly rates look good when potential flyers compare clubs. It makes short hops very expensive.
I've always thought that charging on Hobbs time was the worst possible arrangement encouraging rushed checks - and possibly even taxiing with the electrics off...
I've always thought that charging on Hobbs time was the worst possible arrangement encouraging rushed checks - and possibly even taxiing with the electrics off...
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The only recent time I've flown rental, the Hobbs was used, as the tach did not have an hour meter.
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Where I rent, you time your hire by your watch, and you tell them the answer, and they believe you.
Local rental charges TO to Land + 10 minutes. Reasonable as there's a long taxi and some ATC can be very cautious. It's also checkable with the tower.
Our Group use tach to charge - and adjust charges to make enough profit to cover upgrades etc. As we own our kitty, it doesn't matter if we're too high for a spell.
Our Group use tach to charge - and adjust charges to make enough profit to cover upgrades etc. As we own our kitty, it doesn't matter if we're too high for a spell.
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The airframe and engine log books are required to note daily the total time airborne and the number of flights. I think this is the only legal time recording requirement for a simple single piston. A Hobbs is fairly useless for this unless it's got a link to airspeed or undercarriage. However, industry practice is to note the Hobbs time and subtract 5 mins from each end of the flight. (or 6 mins if you're a purely decimal organization).
As you say, the Hobbs encourages not only rushed checks but 'firewalling' the throttle during flight. However, it is usually the only way of accurately recording elapsed time so most people rub along with it. I can't imagine any aircraft operator taking the whole of the Hobbs time as aircraft log book time for maintenance purposes. The difference SHOULD be around 20%.
At one place I worked, we used Tacho time. Over a period, it trued out the same as airborne time and was accepted by the CAA as an equivalence. The big plus with this is that it encourages people to use sensible airborne power settings and on the ground, any delay at the hold is less expensive.
What's needed is a reliable airborne time recording system. Many GPS offer this facility. This still doesn't get round the problem of hirers firewalling the throttle, though.
Cheers,
TOO
As you say, the Hobbs encourages not only rushed checks but 'firewalling' the throttle during flight. However, it is usually the only way of accurately recording elapsed time so most people rub along with it. I can't imagine any aircraft operator taking the whole of the Hobbs time as aircraft log book time for maintenance purposes. The difference SHOULD be around 20%.
At one place I worked, we used Tacho time. Over a period, it trued out the same as airborne time and was accepted by the CAA as an equivalence. The big plus with this is that it encourages people to use sensible airborne power settings and on the ground, any delay at the hold is less expensive.
What's needed is a reliable airborne time recording system. Many GPS offer this facility. This still doesn't get round the problem of hirers firewalling the throttle, though.
Cheers,
TOO
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Money-wise, at the end of the day (for the same time actually in the air) do you want to be charged 6 hours at £80 per hour or 8 hours at £60, depedning on how the "time" was measured? Either way, the hirer has to cover their costs.
Yes, standardised ways of measuring "time" might be useful for comparison. But then.....
Standardised ways of doing things was meant to be one of the benefits of the EU!!
And even if the way of displaying rates was standardised, I wouldn't hire on cost alone. Just like I feel Easyjet is worth a few quid - not many, but a few - over Ryanair.
Yes, standardised ways of measuring "time" might be useful for comparison. But then.....
Standardised ways of doing things was meant to be one of the benefits of the EU!!
And even if the way of displaying rates was standardised, I wouldn't hire on cost alone. Just like I feel Easyjet is worth a few quid - not many, but a few - over Ryanair.
Try flying helicopters at an airfield in Leicestershire and see how you get on.....
" Where I rent, you time your hire by your watch, and you tell them the answer, and they believe you. "
" Where I rent, you time your hire by your watch, and you tell them the answer, and they believe you. "
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Most of the rentals I have done has been choc's off/on
tiger club when I was there did it tacho + (think it was 0.2 for the cap10 which they then reduced to 0.12 but put up the hourly rate)
Tacho I think is generally fairest as you can run around at 2200 rpm and pay less than running around at 2400 rpm.
I think chocs off/on or hobbs just encourages a pilot to run at 2500 rpm to get where he is going quicker and save money that way leaving the school/owner facing with higher fuel/maintenance bills
tiger club when I was there did it tacho + (think it was 0.2 for the cap10 which they then reduced to 0.12 but put up the hourly rate)
Tacho I think is generally fairest as you can run around at 2200 rpm and pay less than running around at 2400 rpm.
I think chocs off/on or hobbs just encourages a pilot to run at 2500 rpm to get where he is going quicker and save money that way leaving the school/owner facing with higher fuel/maintenance bills
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Our club charges airborne time plus 0.2. The airborne time is measured on a Hobbs meter with an air switch. It is a good system as it does not incentivise pilots to skip the warm up, or taxy too fast. This often means that you log more time than you pay for.
Always worth checking the method used for charging before signing up to a school or renting. It can make a significant difference to the cost.
Always worth checking the method used for charging before signing up to a school or renting. It can make a significant difference to the cost.
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Our club and group both charge airborne + 5 min. We all also put into our logbooks airborne + 5 min. In our group, if you do aeros, you pay for an extra 5 min to cover the fuel. It all works out, checks aren't rushed. It doesn't stop people firewalling during a cruise but then we have few people who are flying needing to get anywhere.
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Our group aircraft had both hobbs and tacho. The tacho was only available on one of the pages of the menu so hobbs was used for simplicity in charging ourselves. Tach was used in the engine log for checks etc.
The hobbs. which was master switch and oil pressure activated recorded 16% more.
The flying club I was a member of some time ago used takeoff to touchdown plus 10 minute which was very fair but was occasionally abused by the hirers.
D.O.
The hobbs. which was master switch and oil pressure activated recorded 16% more.
The flying club I was a member of some time ago used takeoff to touchdown plus 10 minute which was very fair but was occasionally abused by the hirers.
D.O.
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Tach was used in the engine log for checks etc.
When I was working as full time instructor a student came in after an hour of circuits looking very worried. The Hobbs had failed internally and the only wheel turning was the "tens" numbers. His circuit session had increased the Hobbs by 90 hours 
I could not resist and told the dispatcher to bill him for 90 hours saying he had to pay what the Hobbs recorded.
The poor guy just about broke down in tears so I hastily let him off hook
This issue is a classic example of what is versus what should be.
What should be: That the hire rate reflects wheels up to wheels down and the pilot is trusted to accurately record and report flight time and airtime by using his/her watch.
What is: Taxi time costs the school next to nothing and allows them to post a lower hourly rate over what a rate covering only airtime would be. Most pilots shop by numbers and so the higher but more accurate rate of charging airtime only, would be business suicide. Also a significant number of renters would abuse an honour system therefore again hurting the financial viability of the school
Sad to say the Hobbs engine start to stop system of charging time is going to remain the industry standard.
I could not resist and told the dispatcher to bill him for 90 hours saying he had to pay what the Hobbs recorded.
The poor guy just about broke down in tears so I hastily let him off hook
This issue is a classic example of what is versus what should be.
What should be: That the hire rate reflects wheels up to wheels down and the pilot is trusted to accurately record and report flight time and airtime by using his/her watch.
What is: Taxi time costs the school next to nothing and allows them to post a lower hourly rate over what a rate covering only airtime would be. Most pilots shop by numbers and so the higher but more accurate rate of charging airtime only, would be business suicide. Also a significant number of renters would abuse an honour system therefore again hurting the financial viability of the school
Sad to say the Hobbs engine start to stop system of charging time is going to remain the industry standard.