Tach/Hobbs

[dans2992]

So I was renting a Seneca from a flight school for training. The first one I was in had a Hobbs meter connected to the master - no problem.

Then the flight school got a new one. It did not come with a Hobbs meter, so the owner decides to use "tach x 1.3" until he gets the Hobbs meter installed.

I go on a XC flight that was 4.1 hours according to my watch. Tach x 1.3 comes out to 4.7 hours. Tach time on each engine was within .02 of the other engine.

I bring this up to the flight school owner and he says "that's industry standard, I've been doing this for 20 years......". Basically "don't question me". I tried to explain that it depends on how much "ground time" vs. cruise, etc, and that I think "tach time" is calibrated at 100% = 2300 RPM, so if you run at 2400 or 2500, you're actually paying _more_ than clock time.

He somewhat acknowledged this, but then basically said "it's industry standard, nobody else is complaining, and it's the best we have until a Hobbs meter is installed"

At this point, it was not worth fighting about because I was just going to get my multi and be done with it. He does have the cheapest multis in the area.

Thoughts? I flew the other plane for the rest of the training as much as I could.

 

[flyingron]

Tach time isn't time, it's a number of revolutions divided by some reference revolutions per hour number. There's nothing that says billed time has to equal flight time. 1.3 x Tach is a common fudge. How accurate it comes to depends on where the reference point is versus how you set your power settings. If you run around in what we call "Full Rental Power" you'll chalk up more tach time than if you maintain a lower power setting.

Note that neither the tach nor hobbs really depicts flight time or time in service in most cases. You can use your watch but the FAA will accept the paid for flight time.

 

[poadeleted20]

There is no such "industry standard". However, it's his plane, and in this country, that means he can charge whatever he likes as long as someone's willing to pay it.

 

[frfly172]

Tach in most schools without a Hobbs is usually 1.2,1.3 for billable time.

 

[C182P]

He does have the cheapest multis in the area.

Thoughts? I flew the other plane for the rest of the training as much as I could.

Are his rates still the cheapest after the 1.3xTach factor? If so, then you should be happy (and still fly the Hobbs if you thing that you pay less for the same usage)... and if not, then you have a decision to make.

 

[poadeleted20]

Tach in most schools without a Hobbs is usually 1.2,1.3 for billable time.

My experience is rather different, and I've never in 45 years of flying seen a school do that. I have, however, seen their hourly rates set higher for tach time than for Hobbs time, but YMMV. Regardless, there is definitely no "national standard" for a tach time multiplier published by the FAA or any national trade association for the purpose of charging for aircraft rentals.

 

[Blackhawk]

As Ron pointed out there is no industry standard for Hobbs time. I've seen some operate off of airspeed, electrical, shakers, oil,pressure... Many types.
Now if you are concerned about FLIGHT TIME that has nothing to do with a Hobbs or a tach though we often use these for convenience. Flight time is defined by the FAA-
"(1) 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; or..."

This can be a critical difference when you get into commercial duty times as a 135 crew could be incorrectly loggin their flight time using a Hobbs.

 

[flyingron]

Especially since my Hobbs is on the gear as are on many of the heavier iron (which closely fits the time in service definition for maintenance). It is short of the pilot time definition by usually 15 or so minutes even at my uncontrolled field and can be substantially more at a place like IAD.

 

[ARFlyer]

The Hobbs for our twins is tied into the master switch.

It use to be tied into the right engine oil pressure. However, it got changed when they found out people were killing the right engine and just flying with the left the whole flight.

Typically Tach Time will end up a few points cheaper then Hobbs. Everyone always tries to grab the Hobbs INOP aircraft.