how high can you get in an approach on the 737
Only half a speed-brake
mamad:
It is quite hard to say. If you fly the A/C within modern day SOP brackets, as a simple line pilot you will never know. The SOPs are built with a margin, and you never get to learn where the hard limit is because you never get to experience it.
Sort of Catch 22, or the traditional superior knowledge vs. superior skills situation.
But para 1 above is partly bs, pilots happen to travel outside SOP profile now and then. Hence the answer to your question could go like this: Each pilot's limits are different, since they are based on how badly we mismanaged before, and what the outcome had been.
a) couldn't make it to stable approach gate at 1000 and went around -> will never start an approach with that much energy again;
b) made it to to stable approach gate at 1000 sweatting all over -> could do it again, but nothing more.
My personal limit on 9 NM final would be 1500 on top (some excess speed included), if 2000 on top at 9 NM with slow speed and good "drag conf" I may give it a try and see how it ends up. Anything more - "unable for approach".
Love your original question.
It is quite hard to say. If you fly the A/C within modern day SOP brackets, as a simple line pilot you will never know. The SOPs are built with a margin, and you never get to learn where the hard limit is because you never get to experience it.
Sort of Catch 22, or the traditional superior knowledge vs. superior skills situation.
But para 1 above is partly bs, pilots happen to travel outside SOP profile now and then. Hence the answer to your question could go like this: Each pilot's limits are different, since they are based on how badly we mismanaged before, and what the outcome had been.
a) couldn't make it to stable approach gate at 1000 and went around -> will never start an approach with that much energy again;
b) made it to to stable approach gate at 1000 sweatting all over -> could do it again, but nothing more.
My personal limit on 9 NM final would be 1500 on top (some excess speed included), if 2000 on top at 9 NM with slow speed and good "drag conf" I may give it a try and see how it ends up. Anything more - "unable for approach".
Love your original question.
Last edited by FlightDetent; 5th Aug 2013 at 23:08.
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Originally Posted by JT
The early 733 FMS descent profile was an exercise in fairytales for the little ones at night.
The only way to get around that uncertainty is to build in conservatisms which result in the aircraft using more fuel.
Last edited by HazelNuts39; 6th Aug 2013 at 07:57.
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FMS and winds
Of course .. as we only had a rough idea from the forecast which, itself was a rough idea .. ie fantasyland. Easiest real time option was to do it using the Mk1 grey matter all the way down and vary the speed a few knots here and there as necessary to keep bracketing the desired gradient profile .. and a lot of us flew the entire descent hand flown to maintain the scan rate skills .. FD either off or ignored. Much less conservative overall due to the higher data sampling rate than programming the box in cruise with comparatively significant conservatism.
Sometimes, just for fun, we might plug in some forecast winds. That just confused the issue further and we would still just ignore the box's prognostications.
The SOPs are built with a margin, and you never get to learn where the hard limit is because you never get to experience it.
And that's fine, if necessarily conservative and, to some extent, expensive.
couldn't make it to stable approach gate at 1000 and went around
Three observations -
(a) that sort of experience is indicative of stuffing the nose down and going along for the ride. The pilot has to be the boss and monitor all the way down, correcting deviations from plan as appropriate. If it isn't going to work, it becomes pretty obvious a long ways earlier than the final gate.
(b) alternatively, discuss with other pilots, especially those more experienced, try some tests in sim playtime, and revise one's own knowledge. Should the situation arise again, one should be able to perform much better than first time around.
(c) a miss is not a source of embarrassment .. it merely acknowledges that, for whatever reason, the history didn't match the plan to an extent that prudence dictated an escape option. It's only a concern if a pilot continually can't get things right .. the odd miss is a tick in the pass box.
-> will never start an approach with that much energy again
I believe the technical term for that is "learning" ?
made it to to stable approach gate at 1000 sweatting all over -> could do it again, but nothing more
.. but VERY satisfying. The difficult bit was carrying off the "doesn't everyone do it that way" nonchalance ... maybe, next time, one gives oneself an extra mile's worth of fat to reduce the workload ?
Of course .. as we only had a rough idea from the forecast which, itself was a rough idea .. ie fantasyland. Easiest real time option was to do it using the Mk1 grey matter all the way down and vary the speed a few knots here and there as necessary to keep bracketing the desired gradient profile .. and a lot of us flew the entire descent hand flown to maintain the scan rate skills .. FD either off or ignored. Much less conservative overall due to the higher data sampling rate than programming the box in cruise with comparatively significant conservatism.
Sometimes, just for fun, we might plug in some forecast winds. That just confused the issue further and we would still just ignore the box's prognostications.
The SOPs are built with a margin, and you never get to learn where the hard limit is because you never get to experience it.
And that's fine, if necessarily conservative and, to some extent, expensive.
couldn't make it to stable approach gate at 1000 and went around
Three observations -
(a) that sort of experience is indicative of stuffing the nose down and going along for the ride. The pilot has to be the boss and monitor all the way down, correcting deviations from plan as appropriate. If it isn't going to work, it becomes pretty obvious a long ways earlier than the final gate.
(b) alternatively, discuss with other pilots, especially those more experienced, try some tests in sim playtime, and revise one's own knowledge. Should the situation arise again, one should be able to perform much better than first time around.
(c) a miss is not a source of embarrassment .. it merely acknowledges that, for whatever reason, the history didn't match the plan to an extent that prudence dictated an escape option. It's only a concern if a pilot continually can't get things right .. the odd miss is a tick in the pass box.
-> will never start an approach with that much energy again
I believe the technical term for that is "learning" ?
made it to to stable approach gate at 1000 sweatting all over -> could do it again, but nothing more
.. but VERY satisfying. The difficult bit was carrying off the "doesn't everyone do it that way" nonchalance ... maybe, next time, one gives oneself an extra mile's worth of fat to reduce the workload ?
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To be honest the forecast winds, especially if downloaded right at TOD are usually very accurate these days. Nevertheless being high on approach still happens for a number of reasons.
Personally how I cope with the situation depends how we got into it in the first place. The other day the approach controller into Orly set us deliberately up by clearing us only to 5000' and expecting us to fly the ILS from 10NM being 2000ft high. In a case like that the answer to the ILS clearance is of course an "unable". In other cases, especially if its my own fault, it is easiest to switch it all off and fly the rest at the edge of the envelope and stabilized approach criteria manually which is indeed much easier without the distraction of the auto flight system and FD. And if it doesn't work out a go-around is simply a nice change of pace since they are so extremely rare in normal line flying.
Personally how I cope with the situation depends how we got into it in the first place. The other day the approach controller into Orly set us deliberately up by clearing us only to 5000' and expecting us to fly the ILS from 10NM being 2000ft high. In a case like that the answer to the ILS clearance is of course an "unable". In other cases, especially if its my own fault, it is easiest to switch it all off and fly the rest at the edge of the envelope and stabilized approach criteria manually which is indeed much easier without the distraction of the auto flight system and FD. And if it doesn't work out a go-around is simply a nice change of pace since they are so extremely rare in normal line flying.
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NEGATIVE, UNABLE LOUD AND CLEAR!!!!!!!!!!!!!!!!
Perhaps, as Denti says, when we all start saying loud and clear on VHF 1 to the guy/gal on the ground "UNABLE DUE ENERGY MANAGEMENT!", then this speculation on how to get rid of excess energy AT OUR EXPENSE will be consigned to history.
I note that most if not all the contributors to the maths exam answers have excluded the energy due to the mass, so these fancy figures may work one day in the average landing mass aircraft, but will turn round and bite you the day you arrive with tanking fuel or an unusually large payload?
Are the airlines as a block talking to the ATC authorities as a block, about the fundamentals of energy management? I doubt it very much, and as for the ORY case, they will only probably change their ways when one after another inbound refuses their crazy plan and they finally get the message that PHYSICS is involved, and not interpretation, presentation and style.
The odd fool will accept such a proposal as +2,000 ft at 10 miles and demonstrate their skill, panache and daring by getting in with a lot of sweat and possibly excited passengers.
I hope I'm not sitting beside or behind that character, life is too short...........
I note that most if not all the contributors to the maths exam answers have excluded the energy due to the mass, so these fancy figures may work one day in the average landing mass aircraft, but will turn round and bite you the day you arrive with tanking fuel or an unusually large payload?
Are the airlines as a block talking to the ATC authorities as a block, about the fundamentals of energy management? I doubt it very much, and as for the ORY case, they will only probably change their ways when one after another inbound refuses their crazy plan and they finally get the message that PHYSICS is involved, and not interpretation, presentation and style.
The odd fool will accept such a proposal as +2,000 ft at 10 miles and demonstrate their skill, panache and daring by getting in with a lot of sweat and possibly excited passengers.
I hope I'm not sitting beside or behind that character, life is too short...........
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Originally Posted by Barkingmad
the contributors to the maths exam answers have excluded the energy due to the mass
Kinetic and potential energy are both proportional to mass, so the exchange rate between them is independent of mass.
Last edited by HazelNuts39; 8th Aug 2013 at 18:32.
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Decimal 5 Mass by V Squared.
Hazelnuts; I find your post baffling.
I have recently handled the 738NG at max landing weight, luckily our planes are mostly full and we were "tanking" fuel.
I can assure you the 'frame badly needed extra track miles to slow down when compared with the same 'frame 5 tonnes lighter.
Why does Mr Boeing provide me with distance tables showing increasing track miles needed with increasing weight e g 40/50/60/70 tons from identical heights?
And this ToD manoeuvre is only flown close to Vref in the last few miles so I don't get the connection?
Energy (momentum) is the product of the mass times velocity, so why do you think it is not a relevant and important factor?
I have recently handled the 738NG at max landing weight, luckily our planes are mostly full and we were "tanking" fuel.
I can assure you the 'frame badly needed extra track miles to slow down when compared with the same 'frame 5 tonnes lighter.
Why does Mr Boeing provide me with distance tables showing increasing track miles needed with increasing weight e g 40/50/60/70 tons from identical heights?
And this ToD manoeuvre is only flown close to Vref in the last few miles so I don't get the connection?
Energy (momentum) is the product of the mass times velocity, so why do you think it is not a relevant and important factor?
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Originally Posted by BARKINGMAD
Energy (momentum) is the product of the mass times velocity
½*m*V² + m*g*H
where m = mass, V = velocity, g = acceleration of gravity, and H = height.
So for two points 1 and 2 of equal energy, we get: H2 - H1 = ½*(V2² - V1²) / g
Why does Mr Boeing provide me with distance tables showing increasing track miles needed with increasing weight
Vref, on the other hand, varies with weight so that the L/D and glide angle are constant.
Last edited by HazelNuts39; 11th Aug 2013 at 15:24. Reason: additional text
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As an illustration to my post #49, I thought the following graph might be interesting. It shows the variation of lift-to-drag ratio (L/D) with airspeed.
For example at 1.4 times the minimum drag speed Vmd, the L/D is about 0.8 times the maximum L/D.
The relation is based on a 'parabolic' drag polar and is independent of configuration, weight or aircraft type.
For example at 1.4 times the minimum drag speed Vmd, the L/D is about 0.8 times the maximum L/D.
The relation is based on a 'parabolic' drag polar and is independent of configuration, weight or aircraft type.
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Appreciate
Sorry for the late response. I thought the thread deleted when it was moved from tech log to questions.
Thank you so much guys for these answers.
These discussions and the infos shared enhanced my confidence greatly at the time. It took me from trying
To be slighly low (because scared to be high and end up unstable ) to being a normal pilot (not bold). Yes in todays strict SOP environment we tend to know less and less of our aircraft real capabilities eventhough we might need it when **** hits the fence !
Thank you so much guys for these answers.
These discussions and the infos shared enhanced my confidence greatly at the time. It took me from trying
To be slighly low (because scared to be high and end up unstable ) to being a normal pilot (not bold). Yes in todays strict SOP environment we tend to know less and less of our aircraft real capabilities eventhough we might need it when **** hits the fence !
Last edited by mamad; 19th Jun 2016 at 10:05.
