Time or Fuel economy

[LearjetGA]

Good evening.

Just a general question : You have a substantial and unexpected tailwind (50 kt)at your cruising altitude on your 500 mile leg. Would you power back to keep your usual groundspeed, let's say 440 kt or would you keep normal power and be there let's say 10 minutes early ? Of course Lifeguard and express cargo excluded.

LearjetGA

 

[pa56pa]

hmmm.. an hour and 5 min... becoming a 55 min. flight?? I don't think you would save 10 min. I'd rather save the fuel... besides, below 10000 ft., we're all at the same speed, possibly slowed down by ATC... so much for the time savings... obviously, it would be different if you were lifeguard.

 

[2000flyer]

What is the cost difference between 10 minutes of fuel or 10 minutes on the aircraft?

In aircraft like the Ultra I fly, max continuous thrust is the most economical way to fly. Pulling the power back may save you fuel, but the added time on the aircraft is more costly than the fuel you saved.

2000Flyer

 

[Gulfstream 200]

Fly as fast as you can taking into consideration pax comfort (turbulence)

Depending who is on board, saying you slowed down to save a few dollars may get you some dirty looks!

There are better ways to save $$$!

 

[Fokkerflyer]

Mach .82 all the way baby!

Our goal is to get our people where they have to go. Get them there faster, everyone happy.

As G200 said, there's better ways to save $$$.

FF

 

[Roadie]

No reason to go slow unless you have to do a max range profile.

I think the fuel savings notion is an illusion because the $ saved in fuel be offset by the additional time on the airplane. Its not worth the bother to slow to your no-wind groundspeed - youre not really saving anything.

I used to fly with a guy in a Citation 650 operation who was under the delusion that he needed to climb as high as possible to save fuel / $DOC, and even on short trips he'd take it to 410/430/450. The extra time to climb (and slower groundspeed) offset the fuel savings. We tried to prove the point one time on a trip involving two airplanes on a flight between the same city pairs at the same time. He saved about 200 lbs but got to the destination 4-5 min later.

 

[pa56pa]

True, but like I said, in reality a 500 mile trip.... cmon... you're NOT saving 10 minutes..... besides... the lears usually go M.77, not .82.... (<<<< I wish!!) G200 said it in quote... "don't analyze it...." and to the person in the C650, that's ridiculous to climb to 410 on a 500 mile leg!! now, that's not thinkin period.... lol

 

[501261]

If conditions permit, going fast is "generally" more economical in most business jets.

Why? Because the few bucks you save in fuel are spent on the extra dollars you will be spending writing checks to MSP or JSSI or other power by the hour programs or warranty programs that "most" business jets are on. On average those programs are about $120 per hour per engine. So taking an extra 10 minutes might save $40 in fuel, but cost you an extra $40 in MSP payments.

You also have to consider that if you always fly at economy fuel setting you are going 10% slower meaning you will be spending 10% more time in the air. In money terms that means you will be at your 300 phase check while the guy going fast will only have 270 hours on the airframe.

There are obvious exceptions for turbulence, range profile type trips, but when in doubt go fast.

 

[Roadie]

[and to the person in the C650, that's ridiculous to climb to 410 on a 500 mile leg!! now, that's not thinkin period.... lol

I said Short leg (e.g. 200 or less) - not 500 mile leg. Of course it makes sense to go to 450 on a 500 mile.

 

[Airpiraterob]

faster....faster...faster....oh yeah...

well you can look at it anothe way.

what are you carrying?
what are you doing?
how soon after you get there will you have to do what you just did again?

this came up in charter freight a while back. the faster you can get there then the sooner you can get another charter cargo load. the more revenue cycles you can put on the life of the engines the more money you can make for that given replacement expense. so 5 or 10 minutes here and there add up over the course of a few thousand hours and flights. so...how many more revenue flights can you make on those engines now? will that income pay for the engine overhauls and then have some more left over?....perhaps. so go faster. burn more gas. its good fo rthe economy all around in this case ;>

heh
heh