Why is the t/o climb gradient requirement higher for quads than twins?
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bubbers44:
As I recall Western's OEI turned right from Rwy 16R over town, rather than the "death trap" (my term) left turn through Ratttlesnake gap.
With the performance of must of today's twins, straight-out for 16R OEI is the safest. That wouldn't work in many cases circa 1980.
I suspect J.T. would have heart failure looking at the Rattlesnake left turn.
JT, not as risky as climbing straight out with no performance data. We had no engine out performance procedure for Reno. Our speeds were compatible with the 727 so knowing we could outclimb that by .3% we were golden. We had a private jet so didn't have data for Reno. We used Western Airlines procedures. We had airport altitude and field length data but no procedure. I think we did the only thing we could for a safe operation.
With the performance of must of today's twins, straight-out for 16R OEI is the safest. That wouldn't work in many cases circa 1980.
I suspect J.T. would have heart failure looking at the Rattlesnake left turn.
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That's why I prefer our splays - although I can't see the elevations from the graphic, I suspect that the scenic tour up the valley wouldn't accommodate the expanding splays. With a bit of wind analysis, the valley would just disappear totally ..
Heart failure would only be a consideration were I to be on the aeroplane ...
Surely that could only be countenanced as a day VMC departure option ?
Heart failure would only be a consideration were I to be on the aeroplane ...
Surely that could only be countenanced as a day VMC departure option ?
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J.T.:
This was in the pre-splay days. 300 feet each side of centerline. It was the book OEI track, which made it weather independent.
The procedure, as I recall, was a flaps 5 takeoff, which made it easy to obtain the required KIAS, something on the order of 170 or 180. You began your 15 degree banked turn on an ILS DME fix then held the bank until you achieved the heading that would hopefully take you out of Dodge.
I believe the 727-100 with an engine failure just above V1 would cross the physical end of the runway a fair amount higher than 35 feet. But, to retain that margin the airplane was weight limited on a warm day.
So far as I know, it was never used.
This was in the pre-splay days. 300 feet each side of centerline. It was the book OEI track, which made it weather independent.
The procedure, as I recall, was a flaps 5 takeoff, which made it easy to obtain the required KIAS, something on the order of 170 or 180. You began your 15 degree banked turn on an ILS DME fix then held the bank until you achieved the heading that would hopefully take you out of Dodge.
I believe the 727-100 with an engine failure just above V1 would cross the physical end of the runway a fair amount higher than 35 feet. But, to retain that margin the airplane was weight limited on a warm day.
So far as I know, it was never used.
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Net and Gross climb gradients
I believe you have made a mistake in your chart listing the climb gradients.
2 eng gross gradient is 3.2 and net is 2.4.
4 eng gross gradient is 4.0 and net is 3.0
You have taken the net and subtracted the .8/1.0 instead of subtracting it from the gross
2 eng gross gradient is 3.2 and net is 2.4.
4 eng gross gradient is 4.0 and net is 3.0
You have taken the net and subtracted the .8/1.0 instead of subtracting it from the gross
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The rattlesnake peak turn was fun but noticed on departure if you lost the DME where you start the turn if you lost an engine in the sim you were on your own. We had an approach in there one morning and only the NDB worked. We followed United and they didn't clear the runway so went around asking do we follow the NDB missed approach procedure which was a left turn back to the north. They said yes so we started our turn and the controller said hold your heading, which was right at a mountain and when I asked what heading they disregarded and did the published missed to avoid terrain. Sometimes controllers forget about mountains and just think about midairs in a panick situation. I loved flying there but you had to pay attention.
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bubbers44:
So, taking off to the south if you had an engine failure just above V1 you would do a right 180 (more or less) over town? I recall that is what WAL did many years ago.
As to the 727, the option for the biggest engines would seem to make a difference.
War story: When TWA first planned to operate into Reno in the early 1980s they planned to use only 727-100s and only fly to KLAS. They told our ALPA safety committee with OEI that would permit a straight out climb to a fix in the Carson Valley where a climb in hold would occur. I got the FAA form for the fix and advised them they would enter the hold 1,800 feet below MRA for the fix. Lots of red faces on the company side of that table.
Of course, they also asserted all TWA airplanes could climb straight-out everywhere with OEI. Our ALPA safety committee convinced a senior VP to get us the altitude each mile for a 727-231 at max structural takeoff on KLAS Runway 25 at the critical temperature for that weight. It took 31 miles to get to 1,500 agl. The airplane would have hit the first ridge of mountains west of town. That changed TWA's OEI procedures, big time.
I found this incredible from an airline that sold performance data to other airlines, etc.
Since then, I generally do not trust performance engineering, except JT of course.
I think a couple of these for-hire performance engineering departments often "cook the books" so to speak.
P.S. I think more likely than not, with an engine failure just above V1 in IMC or at night, more likely in those days there would have been CFIT into Rattlesnake Peak regardless of airline.
JT, not as risky as climbing straight out with no performance data. We had no engine out performance procedure for Reno. Our speeds were compatible with the 727 so knowing we could outclimb that by .3% we were golden. We had a private jet so didn't have data for Reno. We used Western Airlines procedures. We had airport altitude and field length data but no procedure. I think we did the only thing we could for a safe operation.
As to the 727, the option for the biggest engines would seem to make a difference.
War story: When TWA first planned to operate into Reno in the early 1980s they planned to use only 727-100s and only fly to KLAS. They told our ALPA safety committee with OEI that would permit a straight out climb to a fix in the Carson Valley where a climb in hold would occur. I got the FAA form for the fix and advised them they would enter the hold 1,800 feet below MRA for the fix. Lots of red faces on the company side of that table.
Of course, they also asserted all TWA airplanes could climb straight-out everywhere with OEI. Our ALPA safety committee convinced a senior VP to get us the altitude each mile for a 727-231 at max structural takeoff on KLAS Runway 25 at the critical temperature for that weight. It took 31 miles to get to 1,500 agl. The airplane would have hit the first ridge of mountains west of town. That changed TWA's OEI procedures, big time.
I found this incredible from an airline that sold performance data to other airlines, etc.
Since then, I generally do not trust performance engineering, except JT of course.
I think a couple of these for-hire performance engineering departments often "cook the books" so to speak.
P.S. I think more likely than not, with an engine failure just above V1 in IMC or at night, more likely in those days there would have been CFIT into Rattlesnake Peak regardless of airline.
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AFAIK, the gross t/o segment 2 climb gradient requirements are
2.4% for a twin (1.6% net)
2.7% for a trijet (1.8% net)
3.0% for a quad (2.0% net)
Since these numbers are with one eng inop, I expected the quads to have a *lower* gradient requirement than twins, not the opposite. I figured that quads would have a larger "engine" error margin (3 op vs. 1 op) thus allowing for a smaller gradient error margin
2.4% for a twin (1.6% net)
2.7% for a trijet (1.8% net)
3.0% for a quad (2.0% net)
Since these numbers are with one eng inop, I expected the quads to have a *lower* gradient requirement than twins, not the opposite. I figured that quads would have a larger "engine" error margin (3 op vs. 1 op) thus allowing for a smaller gradient error margin
