Hi Paul.The left hand scale gives the FAR (or JAR, depending on the chart) takeoff field length, either in feet or meters, depending on airport elevation (the blue lines), takeoff weight and flap setting for the aircraft type/engines shown at the bottom of the chart (off your attachment), the temperature condition (in this case "standard day", +15 C at sea level then ISA temperatures), the runway/conditioning packs/etc conditions shown at top of the chart (again off your attachment).Note that the blue lines change their steepness: at every change of steepness is associated a change of flap setting (note that sometimes in the charts the caption with the new flap setting is missing, but if you take a look at many charts, you'll see that the order is: 25,15,10,5,1).Assume we have 150000 pounds TOW:@ sea level we can takeoff with flaps 25 and need about 5200 ft@ 2000 ft, still 25 and about 5800 ft@ 4000 ft, we are very near a change of steepness, but sill with a flap 25 setting, we'll need about 6500 ft@ 6000 ft, we are in the flap 15 region (but very close to the flap 10 too), and we'll need about 8000 ft to takeoff@ 8000 ft, we need flap 5 adn a little more than 9000 ft.If our weight increases to, say, 170,000 pound, at sea level we can still takeoof with flaps 25 and use 6800 ft, but at 6000 ft we'll need falps 1 and almost 14000 ft of runway !The higher the payload and the higher the filed elevation, the lower flaps settings and the higher field length required.Hope this helps.

A little more info:The end of each section of the curve before it changes slope is the climb limit (i.e., the maximum weight that meets the climb requirements) for that flap setting. The steeper slope sections are associated with what Boeing calls "improved climb performance." Higher takeoff speeds (overspeeding on the ground) are used at the same flap setting to allow higher weights and still meet the climb performance requirements. Overspeeding rapidly eats up runway length (which is why the curve is steeper), but it will provide more weight capability at a given runway length than going immediately to the next lower flap setting.The Boeing charts are provided on that web site link for several models and engine ratings. I've compared the -700 data with CFM56-7B24 engines at 24,200 lb thrust rating to the PMDG data and they do not match at all.Don S.

Couldn't agree with you more Tero.In fact, PMDG did a very good job with the performance documentation for their old FS98 757.Don S.

But did you cut an engine at V1?Don S.

No, Don, I was just telling Paul that the airplane behaved fine. I was flying a quiet trip, no failures at V1. One time I'll try an engine failure at V1 at KJAC and let you know...Happy takeoffs.

I do not have a "real" 737NG manual at hand, I assume that the Boeing performance charts should be accurate.

Inspired by your message I decided to go and have a try at the rejected take off at MAX runway weight, and an engine failure at Vr, climb out.I attempted using the tables in the takeoff performance PDF.Setup: 737-600, EGAC, Ry 04 (5990ft), 15C, 29.92, sea level. 15 flap, Cog 24.1%, N1 full rate 91.6% with auto TO/GA to roll from brakes on after reaching 90% N1.Looking up the Runway Length Weight Limit for the 600 I got the figure, 150.4 x1000lb yellow row.I used the FMC to set up the V speeds, which I didn't write down, but cross referenced OK with the TO speeds in the tables for that weight at 15 degree flap, and OAT, pressure etc..When I ran off the end of the runway on reject and climbed through some poor peoples houses I invetigated further.In the LIMITATIONS pdf it states the MTOW of the 600 is 127,000lb. So most of the information in the tables is redundant anyway, as it's above that limitation. Taking the absolute MTOW from the limitation manual I tried TOs and RJT TOs, plus a couple of engine failures at V1/r and I got away from the airport and up to MSA, 220knots with only a little coaxing and back down and stopped again, even on autoland.Then I noticed something worse. Thank god PMDG don't produce real (percision?? ;);)) manuals for pilots. In the table "Takeoff Speeds - Wet Runway" it gives the Max wieght for runways like:158.7 x1000kg.Em... It wouldn't roll! Never mind accelrate and take off at that weight. Thats.... 158.7 x 2.2 x 1000 = 349,140lbs!!!OK, so thats jsut a sleepy error, we know they meant pounds.

Hi Paul,Happy to see you were inspired to try some flight testing yourself. I think what you found is that the 737-600 is actually not limited by field length on a 5990 foot runway (at least at whatever flap setting the PMDG data is for). For your original flight, the maximum weight that you got from the yellow row in the table is the climb-limited weight, not a field-length-limted weight. It is the maximum weight that will meet the climb requirements (2.4% gradient with the gear up and one engine inoperative in this case) for the altitude and temperature at the airfield.The field-length-limited weight for your flight is around 159,000 lbs, which is greater than both the climb-limited weight and, as you found out from the limitations document, the structural limit weight. In other words, you are limited to a lower takeoff weight by either the structural limit weight or the climb limit weight, not the field length limit weight. (I wouldn't worry too much about the structural limit weight in doing these performance tests, though, since nothing bad is going to happen in this sim if you're above it.)If you're going to test a field-length limited weight for the -600 using the PMDG data that is lower than the structural and climb limit weights, you will need to find a runway that is around 4,000 feet long.Don S.