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MD-80 Pilots, Know About Fuel Savings?  
User currently offlineSLOflyer From United States of America, joined Sep 2009, 2 posts, RR: 0
Posted (5 years 1 month 2 weeks 1 day 8 hours ago) and read 6336 times:

I'm curious if there are any MD-80 pilots out there that can share anything about what the operators have them do to help save fuel. Is this much of an effort? Do they have specific flight instructions to help save fuel burn?

thanks in advance!

9 replies: All unread, jump to last
 
User currently offlineIAHFLYR From United States of America, joined Jun 2005, 4790 posts, RR: 22
Reply 1, posted (5 years 1 month 2 weeks 1 day 7 hours ago) and read 6323 times:

Well not an MD80 pilot but my guess is from controlling a few MD80, 81, 82, 83, and 88's in my time, the first thing would be to slow down a bit!

A climb speed at 330 KIAS certainly has to burn alot of gas, then a cruise of .82 though moving through the air must increase fuel burn.....and on approach I'd think attempting to stay at or above the clean maneuvering speeds when able certainly helps on gas consumption.

Can't wait to see what the Mad Dog drivers say!

[Edited 2009-09-16 18:02:30]

[Edited 2009-09-16 18:49:39]


Any views shared are strictly my own and do not a represent those of any former employer.
User currently onlineStarlionblue From Greenland, joined Feb 2004, 17079 posts, RR: 66
Reply 2, posted (5 years 1 month 2 weeks 1 day 6 hours ago) and read 6313 times:

My guess is that climb speed is a trade-off. Faster climb burns more fuel per minute, but gets you to the economical cruise altitude faster. There's probably a break-even point there somewhere.


"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineJoseKMLB From United States of America, joined May 2008, 493 posts, RR: 0
Reply 3, posted (5 years 1 month 2 weeks 22 hours ago) and read 6218 times:

Slow down a bit think there cruise is like .76 mach but not sure on that.

User currently offlinePGNCS From United States of America, joined Apr 2007, 2834 posts, RR: 45
Reply 4, posted (5 years 1 month 2 weeks 16 hours ago) and read 6134 times:

It is similar for most aircraft: fly the proper speeds, fly with a clean wing, and fly at the most economical altitudes.

Your question is very broad, but the optimum Mach speed at cruise will vary, especially for different wind conditions. Typical optimum economy speeds are somewhere around .74-.77 Mach, and typical economy climbout speeds are in the vicinity of 310 KIAS until reaching climb Mach. Descent speeds vary widely depending on what cost index you are using in the FMS, but are generally slower than the climb speeds. A low cost index can yield an econ descent profile of 250 KIAS, which will generally not please ATC. Typically the MD-80 descends at a Mach number around our cruise Mach, converting to a descent speed around 290-310 KIAS. Understand that ALL of this is subject to ATC needs, and few flights are optimally fuel conserving. We have MANY pages of text in manuals, bulletins, etc., that discuss methods of conserving fuel.

Other techniques are minimizing APU use and using single engine taxi procedures when possible. Many of the newer ATC Departure Procedures (and some Arrivals, as well) have speed restrictions the MD-80 can't comply with clean, which will require leaving the slats extended for much longer than normal. SLC is famous for this, as is DFW. Some procedures in CLT and ATL also come to mind, but I can't recall the specifics right now.

IAHFLYR is generally correct, that to optimize fuel burn we would typically like to go a tad slower than ATC would like to fit in with other traffic (although nothing like an ERJ for example), probably cruising around .75 or .76 on average, though complying with anything from .70 to .79 is normally not a problem. 330 KIAS on the climbout is actually not too far off from the cost indexes that are commonly used; I see speeds in the high 320's pretty commonly; when the CI changes downward you can see much slower speeds. We don't like speed restrictions below 250 KIAS, as depending on weight, we may have to configure with slats which hugely increases fuel burn and gives a pronounced nose high pitch attitude with slats extended that some people find uncomfortable.

Hope this gives you a general idea of some of the considerations involved.


User currently offlineIAHFLYR From United States of America, joined Jun 2005, 4790 posts, RR: 22
Reply 5, posted (5 years 1 month 2 weeks 15 hours ago) and read 6089 times:



Quoting PGNCS (Reply 4):
Many of the newer ATC Departure Procedures

Some of those speed I know are for airspace or TERPS requirements in order to keep a turn contained within the route width for the procedure, DFW and LAS come to mind.



Any views shared are strictly my own and do not a represent those of any former employer.
User currently offlinePGNCS From United States of America, joined Apr 2007, 2834 posts, RR: 45
Reply 6, posted (5 years 1 month 2 weeks 10 hours ago) and read 6020 times:



Quoting IAHFLYR (Reply 5):
Quoting PGNCS (Reply 4):
Many of the newer ATC Departure Procedures

Some of those speed I know are for airspace or TERPS requirements in order to keep a turn contained within the route width for the procedure, DFW and LAS come to mind.

I'm sure that's true; SLC is the same. I was just saying that we don't like them due to configuration and fuel burn issues as that was the focus of the thread. The DFW ones aren't that bad as the restrictions are fairly close in to the airport so operational impact is pretty small; the SLC ones are much more annoying as they last much further from the field. I have nothing at all good to say about the new SLC departures or arrivals.

The MD-80 has modestly high clean maneuver speeds, especially when heavy, which makes flap/slat management a factor in some flight regimes. The good news is the airplane has very high flap speeds, unlike competitors (especially Boeing) which is a big help and helps avoid flap overspeeds. Slat extend, Flap 11 max speed is 280 KIAS, for instance. Even Flaps 15, which gets the slats fully extended, is 240 KIAS max.


User currently offlineIAHFLYR From United States of America, joined Jun 2005, 4790 posts, RR: 22
Reply 7, posted (5 years 1 month 2 weeks 6 hours ago) and read 5964 times:



Quoting PGNCS (Reply 6):
I was just saying that we don't like them due to configuration and fuel burn issues as that was the focus of the thread

I completely understand the dislike due to fuel burn, and that is yet another issue for the FAA's newest buzz phrase, NextGen, and having all aircraft perform to the same standards. All airframes are not the same as you mention and to think that all procedures developed will be cost effective for each airframe is insane.



Any views shared are strictly my own and do not a represent those of any former employer.
User currently offlineKcrwFlyer From United States of America, joined May 2004, 3834 posts, RR: 7
Reply 8, posted (5 years 1 month 1 week 3 days 17 hours ago) and read 5574 times:



Quoting PGNCS (Reply 4):
Some procedures in CLT and ATL also come to mind, but I can't recall the specifics right now.

Nothing to do with MD-80's here, but relating to CLT arrivals: I was on a CR2 arriving from the North West in August ( I think the JOHNS2 approach), and we flew low with flaps 20 for upwards of 25 minutes.


User currently offlinePGNCS From United States of America, joined Apr 2007, 2834 posts, RR: 45
Reply 9, posted (5 years 1 month 1 week 3 days 10 hours ago) and read 5497 times:



Quoting KcrwFlyer (Reply 8):
Quoting PGNCS (Reply 4):
Some procedures in CLT and ATL also come to mind, but I can't recall the specifics right now.

Nothing to do with MD-80's here, but relating to CLT arrivals: I was on a CR2 arriving from the North West in August ( I think the JOHNS2 approach), and we flew low with flaps 20 for upwards of 25 minutes.

My point wasn't that ONLY MD-80's are adversely affected, but since this thread was on fuel conservation methods specifically on the MD-80, that was what I was discussing. I'm not making light of your point; ATC speed restrictions force all types of aircraft from optimum profiles, which is why, unless ATC really needs them, I don't like them. Clearly in busy terminal areas there will be more speed assignments as ATC does their magic getting us in and out of the airport, I just ask them not to put speed restrictions on us when they don't really need them.


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