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Climb Speed

Old 17th May 2009, 15:19
  #1 (permalink)  
Thread Starter
Join Date: May 2005
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Climb Speed

Hi all,

I am flying with a guy at the moment who believes climbing at 300 feet permin in RVSM rocketing along at 320 knots is the best way to climb as you make up time. Apart from the obvious extra fuel burn I was wondering, as I dont know the price of things, what you all think regarding the trade off of doing this. I dont believe the extra speed offsets the price of the wasted fuel, and I dont think its significantly faster. He wont listen to my or other copis views on this.

Any thoughts? On the theory and how to confront the Capt?


ollycopter is offline  
Old 17th May 2009, 16:37
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Last time I looked you aren't even allowed to do that since your rate of climb should be within the range of 500 - 1500 fpm in RVSM airspace.

If he doesn't want to listen to his colleagues, rub the relevant legislation in his face...
Longhitter is offline  
Old 17th May 2009, 16:38
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Is he doing this in V/s?

For a given IAS you actually achieve a better TAS at higher altitude. If he is deliberatley climing slower, but is NOT maintaining full climb thrust, he is actually going to take longer to get where he is going.

You could tell him that if he REALLY wants to go fast, maintaining the altitude at which 320IAS is equal to cruise MACH (?.80? in a 320?) will give him the best TAS, but will use a shed load of fuel. Is he willing to justify this?

Bottom line would be, what are your company SOPs?
Wizofoz is offline  
Old 17th May 2009, 17:17
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From 747 Classic FCTM -
The following table shows optimum climb vs. gross weight for min trip fuel.
500,000 lbs (227 tonnes) = 290 KIAS - M. 83
600,000 lbs (273 tonnes) = 305 KIAS - M. 83
700.000 lbs (318 tonnes) = 320 KIAS - M. 83
800.000 lbs (364 tonnes) = 335 KIAS - M. 835
833,000 lbs (377 tonnes) = 338 KIAS - M. 84
The above speeds are valid for 747-100/200 types.
The 747-300 - requires 10 KIAS and Mach .01 higher speeds.

Happy contrails
BelArgUSA is offline  
Old 17th May 2009, 22:29
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Basically he climbs with max climb thrust at as fast a speed as possible. I have clocked him at 52 minutes to climb to cruise in an aircraft that can climb to that cruise alt in 20 to 25 comfortably at the weight we were. He says that the money spend on fuel is made up for by getting there faster. Today he said we should refuel full so we can save money as its cheaper where we are but he will climb out in the same way.. He actually would fill up full everytime he could no matter where we are or what it costs if he was not monitored. He is a nice guy but I just cant seem to get through to him.
ollycopter is offline  
Old 18th May 2009, 22:25
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I have also found captains who have their own theories that differ from the manufacturer recommendations.

When the aircraft manufacturer does their certification test flying, they need to meet two sets of criteria. They need to meet the certification requirements, but they also need to meet the brochure numbers that the marketing department promised to all the customers. They therefore do a series of climb/cruise scenarios to find the ideal cruise climb profile that maximises block speed and/or range and/or payload. They spend a fortune doing this, because the answers are worth literally millions to them. Not all this data makes it to the AFM. Some will be in a supplement, or a planning handbook, or whatever - you may need to check for your type.

But, it is very unlikely that your Captain has inadvertently discovered a better answer than the company test pilots who were paid to find the very best way of operating their machine. You just need to find the appropriate guidance material and lead your Captain to it!
CJ Driver is offline  
Old 18th May 2009, 22:51
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Longhitter has the answer, I think, don't ATC expect a minimum of 500fpm?
parabellum is offline  
Old 19th May 2009, 14:27
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It is not more efficient. If you're in a Boeing put '0' in the cost index and it will display the most efficient speed.

Minimum climb rate is 500' FPM(U.S. standards). Lower climb rate requires notification to ATC.

The most efficient place to increase speed, and decrease time, with the lowest additional fuel burn is on the descent. The least efficient is increasing cruise speed. If you're on a Boeing you can verify this by modifying the cost index and seeing what impact increasing cost index does to the CLB/CRZ/DES speeds. DES is increased first, then CLB speeds, and it takes amazingly high cost index numbers to increase the cruise mach on the FMC.

His statement that the time saving pays for the gas is wrong. You should be able to verify that by crossing checking the time saved vs. fuel used at the first waypoint after top of climb.

Another issue is why do you care what he does? It's not unsafe, you know it's not true, and you say you can't get through to him. If you can't get through to him, like he won't listen to facts that disagree with how he views the world, why bother worrying about him? Mark it down as a lesson for when you upgrade to Captain and the value of being technically correct when you pass on knowledge to your FO's.
misd-agin is offline  
Old 19th May 2009, 19:36
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Maybe my last few years of regimented flying has made me naive but have SOPs been thrown out of the window? Whilst I agree a lot of it makes better use as toilet paper, I think anything to do with fuel planning should be done by the book.

Running through the physics of his assumption in my head tells me he is wrong. The best proof being misd-agin's 4th paragraph.
betpump5 is offline  
Old 20th May 2009, 17:44
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Well in a time like this I think sitting back and not caring about a costly practice would be the worst course of action.. I flew today and after 48 mins we reached cruise. We were behind schedule.. He did not care. We also burned 700 pounds of fuel more then we would have. Its not a 737, 700 is a lot.

I mentioned RVSM again.. He does not care if no one says anything.
ollycopter is offline  
Old 21st May 2009, 13:02
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Adjusting the time (speed) vs fuel burn for a minumum cost is not pilot`s job if CI is provided by company.
Fly the CI speed at any phase of flight for minumum cost. As entering CI to FMGC, we are telling the computer the comparison between Fuel Cost and Othet costs (time related Costs). So, computer optimizes the best speed for minumum cost with real-time effects (wind speed, temp, altitude, weight, remaining route length etc.)

Full Stop
JABBARA is offline  
Old 21st May 2009, 13:08
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Never mind the rate of climb, what happened to max 250 knots below 10K?.
kwachon is offline  
Old 21st May 2009, 15:14
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We dont have a cost index. I wish we did. Is it typical in Biz aviation? My guess is no. But still, flying as efficiently as possible should really be a priority.. There is no gain for that fuel burn. Thats my big problem with it.. He does regulary bust 250 below 10000 but who the heck has ever called someone on that? I have never seen it, and I have many hours with this fella.. I may add he has started this practice of slow climbing.. It was not his way before..
ollycopter is offline  

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