It's been a long time since I was a B-727 flight engineer, but maybe I can help. The climb limits mentioned in the landing charts are no doubt for the all engines operating balked landing climb case. The approach limits are for the one engine inoperative climb at various flap settings. Be more specific if you want more.
dtuuri
That's the one I referred to.Its the landing performance chart in particular I'm having a problem understanding.
Right.1. I don't quite understand the section that gives corrections that are to be made to the weight if the planes anti ice is on. I'm assuming it means subtract the necessary pounds from the max landing weight in the section titled
"SUB LB/KT" if you're wing and engine anti ice is on, right?
The minus sign is for a tailwind. Notice the max tailwind component is 10 kts.2. In the section that gives you the runway number and slope, which numbers are for headwind? Is it the numbers with the dash or without the dash?
I dunno. CRT=Correct for? TW=Tailwind? Can't fig'r it oot.3. What does the term "CRT TW"? Does it mean subtract from the max weight if I have a tailwind?'
Sure. You need less runway with anti-skid than without. Same for Auto spoilers vs. manual.4. Can you explain the top that states 'Anti-Skid operational'?
Ahh, there ya go.3. CRT TW is a penalty in weight reduction. For every kt over the CRT TW you have to take a penalty.
It's been a while but here's what I remember. Somebody correct me if I'm wrong. (Usually not a problem around here but I'm married so I can take it)
1. Landing weight is the lesser of the climb limit, runway limit, or structural limit. The engine anti-ice correction applies to the climb limit. In this case at ROC at 0C it shows 219.1. This assures you're not gonna hit something on a go-around. I think this 189100was based on one engine Inop. The SUB LB/KT has nothing to do with it, that is down in the runway limit part of the chart. Draw a line where it says LANDING FIELD LIMIT LENGTHS.
2. Beside the runway, length, and slope there is a column from -10kts to 20kts. Those are your weights. Runway 5 with a 5 kt tailwind (-5) gives you 189100 lbs. A 10 kt headwind is 190000 lbs.
3. CRT TW is a penalty in weight reduction. For every kt over the CRT TW you have to take a penalty. I'm a little fuzzy on this part so maybe someone else can step in.
4. On the Landing Field Length you have 4 columns. Two show anti-skid operational and 2 inop. This is broken down into columns showing auto-spoilers and manual spoilers. These are then broken down into dry or wet runway. Runway 5 with calm winds, goes from 190000 down to 164400 with loss of anti-skid.
The N/A areas mean not allowed. When you have a wet runway, no anti-skid, and a shortish runway you get that.
Take the climb limit weight (go around), the landing field limit weight (get the sucker stopped), and the max structural landing weight and compare. You're limited by the smallest.
That's the one I referred to.
Right.
The minus sign is for a tailwind. Notice the max tailwind component is 10 kts.
I dunno. CRT=Correct for? TW=Tailwind? Can't fig'r it oot.
Sure. You need less runway with anti-skid than without. Same for Auto spoilers vs. manual.
dtuuri
Ok, so just to clarify, assuming my antiiceskid is on, since I'm landing on runway 4 at ROC, I have to subtract 1,177 pounds from my landing weight limit if my spoilers are operational on a dry runway. Is this correct?
FTFY. Anti-ice has no bearing on runway limit. Anti-skid sure would.
dtuuri
Yes.So the anti ice correction is only for the climb limit?
Thats what it is for us too. When we are all engine we use it to start the clean up.Acceleration height, at least at our airline, is the altitude for level off in the event you lose an engine. They are usually runway specific due to obstacles in the later climb segments. You'll notice they are different for different runways.
It's been a long time since I was a B-727 flight engineer, but maybe I can help. The climb limits mentioned in the landing charts are no doubt for the all engines operating balked landing climb case. The approach limits are for the one engine inoperative climb at various flap settings. Be more specific if you want more.
dtuuri
Yes.
Ok, so is it saying subtract 20 pounds from the max climb limit if anti-ice is on? Also, this still doesn't tell us why I would subtract 1,177 pounds from the landing weight limit for runway 4 at ROC.
Not sure where you see 20#. The note at the top says climb performance isn't limiting below 43°C. That implies the cooler it gets, the better the approach climb performance. Above that number (a real hot day), with an engine inop, it struggles.Ok, so is it saying subtract 20 pounds from the max climb limit if anti-ice is on?
Not sure where you see 20#. The note at the top says climb performance isn't limiting below 43°C. That implies the cooler it gets, the better the approach climb performance. Above that number (a real hot day), with an engine inop, it struggles.
dtuuri
ENGINE A/I ON SUBTRACT 0 POUNDS ABOVE -20. DEGREES C
It means no correction (0 lbs) is required above a temperature of -20 degrees C. Since -20C is the coldest temperature in this analysis, no correction is required for anti-ice on at any temperature that it would be used.
When it's colder than -20°C (brrrr), apparently there's never a correction--only sometimes when it's warmer than that. But here, on this runway at this airport, there isn't a correction value even if it is warmer. At a higher elevation, say Denver, things might be different.Well I was referring to the line concerning corrections for anti-ice on below:
What the heck does that mean?
When it's colder than -20°C (brrrr), apparently there's never a correction--only sometimes when it's warmer than that. But here, on this runway at this airport, there isn't a correction value even if it is warmer. At a higher elevation, say Denver, things might be different.
dtuuri
That's 4 degrees below zero Fahrenheit. The air is so dense no corrections are needed--use the next higher temperature numbers for conservatism.What if the temperature is below -20 degrees Celsius? Its weird that it doesn't tell us what to do if it gets colder than -20 degrees. I still can't figure out why I'm subtracting 1,117 pounds from the landing weight limit for runway 4 either.
That's 4 degrees below zero Fahrenheit. The air is so dense no corrections are needed--use the highest temperature numbers for conservatism.
You aren't subtracting 1,117 pounds--you subtract that many pounds for EVERY not over 6 from the tail. The reason is your V1 speed is higher, the takeoff roll is longer and the brake energy available may be less at the higher speed. So you need to be lighter to stop in the runway distance available.
dtuuri
Bingo! Btw, I made edits--I was thinking takeoff earlier.Ahh I see (I think), so that's what the term "CRT TW" means? So if I have a 10 knot tail wind, the overall deduction will be 4,468 pounds from the weight limit?
Bingo!
dtuuri
QNH is the altimeter setting...if the pressure is higher than standard, you can add the weights shown. Lower than standard, subtract.
1/4" CONT and 1/2" CONT refer to depth of runway contamination...not sure what type of contamination, though. Contamination decreases takeoff weight by the amount shown and reduces V1 speed by the amount after the / .
Correct.I see, so KMLI airports current altimeter setting is 30.01 inches of mercury. Since this is higher than standard, I'm adding the weights given in the charts?
you can be certain...I'm not.I'm certain that this is in reference to anything we would consider runway contamination, snow, water, standing slush, ice.
Does anybody know how to interpolate? The numbers below are from a runway analysis landing chart. In the instructions I was given, they somehow got 195.000 pounds as the approach climb limit with an outside air temperature of 8 degrees Celsius. What is the actual formula for getting this answer?
Temp (c): -20 19
Climb WT: 209.1 190.0
1. -20 – 19 = 39
2. 19 – 8 = 11
3. 11 / 39 = 0.28
4. 209,100 – 190,000 = 19100 lbs
5. 19,100 * 0.28 = 5,348
6. 5348 + 190.000 = 195,348
Whew. Damn good thing it says "observe structural limits." Things coulda got ugly without that
Whew. Damn good thing it says "observe structural limits." Things coulda got ugly without that
Just when I thought I had it all figured I find something else. On the bottom of the takeoff performance charts it has the following corrections to be made for weight and speed that I don't quite understand.
QNH +lb/ .1
QNH. -lb/ .1
APT inop-lb
EFWL inop-lb
1/4" cont-lb/V1
1/2" cont-lb/V1
View attachment 44327
Also, am I always supposed to add pounds to the overall takeoff weight limit for Accelerated height?