Random questions
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Random questions
incase of decimal takeoff speeds when calculating from performance graphs, do we take next higher or lower V1/Vr/V2 and why?
737NG specific
Inflight with flaps retracted, if one air conditioning pack fails, the other pack automatically regulates to high flow. And this is inhibited if flaps are extended. Now assuming one pack fails with flaps retracted. Now if the flaps are extended, does the other pack regulate to normal flow? Or is high flow maintained? Could not find any references to this in the FCOM or anywhere.
737NG specific
Inflight with flaps retracted, if one air conditioning pack fails, the other pack automatically regulates to high flow. And this is inhibited if flaps are extended. Now assuming one pack fails with flaps retracted. Now if the flaps are extended, does the other pack regulate to normal flow? Or is high flow maintained? Could not find any references to this in the FCOM or anywhere.
Not sure i understand you Ozgun. You can build a hold at any WPT but you don't tell it how may turns - you simply arm the hold and hit proceed when you want to leave the hold on the types I've flown. Standard holding patterns are built in but we always cross check the radials etc as the database could be wrong.
Can you measure it a decimal place?!!!
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And could you fly a decimal?
OMG the auto throttles are not working, now what? Oh geez, the auto-pilot is disconnected, we are certainly going to have a rough go of it. Brace Brace!
OMG the auto throttles are not working, now what? Oh geez, the auto-pilot is disconnected, we are certainly going to have a rough go of it. Brace Brace!
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for example , the waypoint name is , NUKRO and we select HOLD then select NUKRO and we can choose the holding pattern style for NUKRO point , and this is 1 holding entry for NUKRO point , can you select the second holding for NUKRO ? or third or I do not know how many for NUKRO ??
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Ozgun,
You can have two holds for one waypoint. For instance you might have a hold prior to an ILS approach and a different hold, at the same waypoint, for a missed approach. Try putting any more into the FMC and you'll find the latest one will go to the top of the LEGS page and 'overwrite' the existing one. Obviously the missed approach hold is at the end of the legs. Why would you want any more?
You can have two holds for one waypoint. For instance you might have a hold prior to an ILS approach and a different hold, at the same waypoint, for a missed approach. Try putting any more into the FMC and you'll find the latest one will go to the top of the LEGS page and 'overwrite' the existing one. Obviously the missed approach hold is at the end of the legs. Why would you want any more?
V speeds: If there is only 1 knot in it, who cares which way you go?
But if you have several knots spread, it depends.....
Personal preference is to round up for take-off. Two reasons. 1: I would rather be on the ground than in the air if it is going pear-shaped approaching V1 and, 2: a higher V2 speed provides more margin over Vmca and often a better climb.
Exception to that would be on a limiting or wet/slippery runway, when rounding V1 down makes sense, subject to being within the allowable envelope.
For landing I tend to always round down, e.g. if the landing charts are in 500 kg increments and estimated landing weight is mid point, I will go to the lesser numbers. Given that Vref is 30% above stall speed there is enough margin that if, for example, rounding down resulted in 25% it would still be within an acceptable range for most transport types. Using FMS the numbers are usually more exact, so I would use whatever it gave me, but ignore any decimal points!
Others may disagree and there may be some types that do not handle well right on Vref. Also, I have seen ops manual instructions to always round up. So be it; follow company policy if stated.
But if you have several knots spread, it depends.....
Personal preference is to round up for take-off. Two reasons. 1: I would rather be on the ground than in the air if it is going pear-shaped approaching V1 and, 2: a higher V2 speed provides more margin over Vmca and often a better climb.
Exception to that would be on a limiting or wet/slippery runway, when rounding V1 down makes sense, subject to being within the allowable envelope.
For landing I tend to always round down, e.g. if the landing charts are in 500 kg increments and estimated landing weight is mid point, I will go to the lesser numbers. Given that Vref is 30% above stall speed there is enough margin that if, for example, rounding down resulted in 25% it would still be within an acceptable range for most transport types. Using FMS the numbers are usually more exact, so I would use whatever it gave me, but ignore any decimal points!
Others may disagree and there may be some types that do not handle well right on Vref. Also, I have seen ops manual instructions to always round up. So be it; follow company policy if stated.
Last edited by Mach E Avelli; 11th Dec 2012 at 07:59.
Think practically. What is the tolerance between airspeed indicators? In my type it is around 6 knots. If the ASIs can be 6 knots out, what does it matter if you have rounded a decimal place up or down? Having said that, if you always round in the conservative direction then any compounding errors will also be in a conservative direction. A "conservative direction" isn't always the same though. You might have a V1 that is limited on the low side by VMCG so rounding it down is not the conservative thing to do, but the same V1 might also be limited on the high side by the length of runway remaining in which case rounding up isn't conservative either. In this case I come back to my first point, a knot each way isn't going to matter.
I don't fly the NG but have flown other Boeing 737 series and aircraft with similar pressurization systems. Your clue is in the word 'inhibited'. Think of what you (or more importantly, the certifying authority) would want from a performance point of view.
Often, the manufacturer's educational text is succinct so that pilots whose first language is not English do not get confused. Unfortunately those who are fluent sometimes try to read too much into it. From a purely theoretical angle, of course.......
Often, the manufacturer's educational text is succinct so that pilots whose first language is not English do not get confused. Unfortunately those who are fluent sometimes try to read too much into it. From a purely theoretical angle, of course.......
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Crikey, V speeds to a decimal place!?
Even to 3 significant figures is probably too pedantic.
Do we honestly think that our (notional weight derived) loadsheets give completely accurate TOWs?
More important things to worry about than this one I reckon mate!
Even to 3 significant figures is probably too pedantic.
Do we honestly think that our (notional weight derived) loadsheets give completely accurate TOWs?
More important things to worry about than this one I reckon mate!
Last edited by bucket_and_spade; 11th Dec 2012 at 21:27.
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737NG specific
Inflight with flaps retracted, if one air conditioning pack fails, the other pack automatically regulates to high flow. And this is inhibited if flaps are extended. Now assuming one pack fails with flaps retracted. Now if the flaps are extended, does the other pack regulate to normal flow? Or is high flow maintained?
Inflight with flaps retracted, if one air conditioning pack fails, the other pack automatically regulates to high flow. And this is inhibited if flaps are extended. Now assuming one pack fails with flaps retracted. Now if the flaps are extended, does the other pack regulate to normal flow? Or is high flow maintained?
Rdgs
NSEU
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NSEU is correct.
The operation is through a simple electrical circuit, no electronics involved. The flaps up/not up switch is open when the flaps are up. When not up the switch provides a ground to a relay that de-energizes another relay that creates a open circuit to the B solenoid in the flow control and shutoff valve which controls high/normal flow modes.
The operation is through a simple electrical circuit, no electronics involved. The flaps up/not up switch is open when the flaps are up. When not up the switch provides a ground to a relay that de-energizes another relay that creates a open circuit to the B solenoid in the flow control and shutoff valve which controls high/normal flow modes.
Thank you for the answers. Cleared up now. 