ILS & Autothrottle
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ILS & Autothrottle
When performing an ILS landing in a B737-800, after disconnecting the autopilot a few miles out, I keep the autothrottle engaged, however, the speed continues to drop. The light on the IAS button is still on and switch is engaged. Cannot understand why this is happening?
I'm trying to find a website for ILS approach charts, have searched on Google but can't seem to find any for some reason. Could someone provide me with a link please?
Thanks and evening to one and all.
I'm trying to find a website for ILS approach charts, have searched on Google but can't seem to find any for some reason. Could someone provide me with a link please?
Thanks and evening to one and all.
In manual flight you should use manual thrust as well. Boeing SOPs.
All European AIP charts can be found, after registration, on this site: EAD Basic - Registration Page
good luck with all your flights on flightsim
All European AIP charts can be found, after registration, on this site: EAD Basic - Registration Page
good luck with all your flights on flightsim
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Autothrottle and pitch stability
Airplanes with engines mounted under low wings tend to experience significant pitching moment from thrust. As thrust is increased, the engine location with respect to the cg (i.e., below) causes a nose up pitching moment. This arrangement results in unstable speed stability characteristics when the autothrottle is engaged. If airspeed drops the autothrottle commands increased thrust which pitches the nose up, further reducing airspeed. The opposite happens if airspeed is too high leading to reduced thrust and the coupled nose down response.
When flying manually (neither autopilot nor autothrottle), pilots learn very quickly that throttle advances require nose down pitch commands while nose up command must be added when the throttles are retarded. While the response is inherently unstable, an experienced pilot has no difficulty keeping up as the unstable frequency is quite low.
When flying with the autopilot engaged, the required pitch control inputs to balance thrust pitching moment changes are generated automatically. Care is taken during autothrottle and autopilot design to ensure that the combined system with both autopilot and autothrottle active results in positive speed stability.
It is important to note that for airplanes that include pitch augmentation during manual control (no autopilot) the control system itself tends to compensate for pitch disturbances from thrust changes. For this reason, pilots have found that manual path control with the autothrottles engaged to control speed works well with the 777 and 787. Boeing training supports use of autothrottles during manual path control for these models.
When flying manually (neither autopilot nor autothrottle), pilots learn very quickly that throttle advances require nose down pitch commands while nose up command must be added when the throttles are retarded. While the response is inherently unstable, an experienced pilot has no difficulty keeping up as the unstable frequency is quite low.
When flying with the autopilot engaged, the required pitch control inputs to balance thrust pitching moment changes are generated automatically. Care is taken during autothrottle and autopilot design to ensure that the combined system with both autopilot and autothrottle active results in positive speed stability.
It is important to note that for airplanes that include pitch augmentation during manual control (no autopilot) the control system itself tends to compensate for pitch disturbances from thrust changes. For this reason, pilots have found that manual path control with the autothrottles engaged to control speed works well with the 777 and 787. Boeing training supports use of autothrottles during manual path control for these models.
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Can this nonsense be moved to Spotter's Corner please
I have no idea whether the OP is a pilot or a simmer.
Does it matter ? Is the question one which might reasonably be asked in Tech Log ?
Different matter if the OP's question were quite inappropriate for some reason - however, to move the thread solely because we might think the OP is a simmer appears not to be in the spirit of the forum.
I have no idea whether the OP is a pilot or a simmer.
Does it matter ? Is the question one which might reasonably be asked in Tech Log ?
Different matter if the OP's question were quite inappropriate for some reason - however, to move the thread solely because we might think the OP is a simmer appears not to be in the spirit of the forum.
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In manual flight you should use manual thrust as well. Boeing SOPs.
This is a sweeping statement to make. You SHOULD only use this method if your airline's SOPs happen to be the same as Boeing's.
This is a sweeping statement to make. You SHOULD only use this method if your airline's SOPs happen to be the same as Boeing's.
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Just as "sweeping" that your company knows better then the manufacturer. Really don't understand why an airline would want to deviate from the manufactures recommendations. Anwho, Boeing recommends all in or all out (automation wise) except during take off. Take off you use auto throttle in TOGA mode and obviously autopilot disconnected.
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Our company SOP states that A/T can be used as low as 50' AGL on a CAT I ILS approach, for non-precision approaches at MDA A/P and A/T off.
But it makes the manual flight very unstable
But it makes the manual flight very unstable
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But it makes the manual flight very unstable
Oddly enough, with the L1011 type, autothrust whilst manually flying has no restriction (and, nothing 'unstable' about it), however, a few airlines that operated the type previously, made it standard policy to not do so.
Strictly an airline company decision, not an AFM restriction.
I'm trying to figure out the logic of "all in or all out" guidance. First, at 50 feet, the A/T should go into RETARD mode. But, when hand flying, with moving throttles, the handling pilot should have his hands on the throttles, the throttle position reflects the A/T commanded power and a disconnect results in power being just as selected. This is in opposition to the Airbus design. Finally, when hand flying, A/T takes the power set tong burden off making for better flight path control. Mind you, I have no objection (and do you all automation off for proficiency) to all off, but why a restriction?
GF
GF
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I'm trying to figure out the logic of "all in or all out" guidance. First, at 50 feet, the A/T should go into RETARD mode. But, when hand flying, with moving throttles, the handling pilot should have his hands on the throttles, the throttle position reflects the A/T commanded power and a disconnect results in power being just as selected. This is in opposition to the Airbus design. Finally, when hand flying, A/T takes the power set tong burden off making for better flight path control. Mind you, I have no objection (and do you all automation off for proficiency) to all off, but why a restriction?
GF
So feelings on guarding the throttles?
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411A,
So far it is the only A/T installed type I have flown, but most of the people I have talk to said that the B737 A/T is perhaps one of the most remarkable drawback when compared to other airplanes.
However, I prefer to fly A/T off every time the A/P is off (as recommended by Boeing).
GF,
The retard mode starts at 27' RA. It was one of the main reasons, 50' AGL was chosen as the minimum height in our company.
We used to land with the A/T in the ARM mode, that enables to hand fly the airplane while having alpha floor protection, but because Boeing clearly not recommended this feature, especially in gusty wind conditions, the SOP was revised.
So far it is the only A/T installed type I have flown, but most of the people I have talk to said that the B737 A/T is perhaps one of the most remarkable drawback when compared to other airplanes.
However, I prefer to fly A/T off every time the A/P is off (as recommended by Boeing).
GF,
The retard mode starts at 27' RA. It was one of the main reasons, 50' AGL was chosen as the minimum height in our company.
We used to land with the A/T in the ARM mode, that enables to hand fly the airplane while having alpha floor protection, but because Boeing clearly not recommended this feature, especially in gusty wind conditions, the SOP was revised.
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Really don't understand why an airline would want to deviate from the manufactures recommendations.
Airlines have flown billions of hours in manufacturer's products. Boeing I would guess have flown thousands of hours in comparison. Manufacturers are reluctant to make any changes to their initial operating manuals unless there is a significant safety case to address. They have recognised we live in a litigious society and are massively protective of their own procedures, mainly because that's what went in to print when they launched the aeroplane. Boeing in particular have a very "it's up to you, Jack" approach when giving guidance on how to fly their products. To introduce further rule would leave them exposed to finger pointing and law suits. Hence they put the onus on the pilot to use his best judgement, thus carry the can should something go wrong.
Airlines however are overseen by their local country's governing aviation authority. That authority must approve any change to the airline's procedures which differ from the manufacturer's. As accidents occur over the years, loopholes in operating procedures are closed up by way of adjustment of an airline's SOPs in an attempt to prevent the accident/incident re-occuring. Authorities conduct 6 monthly audits of airlines to ensure their Safety Management System, alongside other Flight Operations Departments, is up to speed with latest safety risks and is doing something about minimising them. Manufacturer's don't do audits on how airlines are flying their aeroplanes. To their mind, once you've bought it, it's up to you how you fly it! (..save for instance the QRH edition change for the 737 some years ago.)
A classic example of manufacturer's approach to standards in comparison to an airline's is the autothrottle function on the B737 manually flown approach. Boeing in its FCTM says disconnect it. Conscientious airlines recognise there is a loophole here that the TOGA thrust function is now lost. Airlines recognise the go-around phase as one of increased workload, thus many promote the use of leaving the A/T in ARM with the SPEED function deselected. This affords the facility of manual throttle, with go-around thrust setting protection. There is a definite safety case for this. How could one possibly argue that complete disconnection of the system is safer? Or is it the preference of care-free pilots to show off their "straight arm" technique on a Go Around as they light a Hamlet cigar?
Airlines have flown billions of hours in manufacturer's products. Boeing I would guess have flown thousands of hours in comparison. Manufacturers are reluctant to make any changes to their initial operating manuals unless there is a significant safety case to address. They have recognised we live in a litigious society and are massively protective of their own procedures, mainly because that's what went in to print when they launched the aeroplane. Boeing in particular have a very "it's up to you, Jack" approach when giving guidance on how to fly their products. To introduce further rule would leave them exposed to finger pointing and law suits. Hence they put the onus on the pilot to use his best judgement, thus carry the can should something go wrong.
Airlines however are overseen by their local country's governing aviation authority. That authority must approve any change to the airline's procedures which differ from the manufacturer's. As accidents occur over the years, loopholes in operating procedures are closed up by way of adjustment of an airline's SOPs in an attempt to prevent the accident/incident re-occuring. Authorities conduct 6 monthly audits of airlines to ensure their Safety Management System, alongside other Flight Operations Departments, is up to speed with latest safety risks and is doing something about minimising them. Manufacturer's don't do audits on how airlines are flying their aeroplanes. To their mind, once you've bought it, it's up to you how you fly it! (..save for instance the QRH edition change for the 737 some years ago.)
A classic example of manufacturer's approach to standards in comparison to an airline's is the autothrottle function on the B737 manually flown approach. Boeing in its FCTM says disconnect it. Conscientious airlines recognise there is a loophole here that the TOGA thrust function is now lost. Airlines recognise the go-around phase as one of increased workload, thus many promote the use of leaving the A/T in ARM with the SPEED function deselected. This affords the facility of manual throttle, with go-around thrust setting protection. There is a definite safety case for this. How could one possibly argue that complete disconnection of the system is safer? Or is it the preference of care-free pilots to show off their "straight arm" technique on a Go Around as they light a Hamlet cigar?
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Kiltie,
I still fly the old -200's with the SP177's and the 727-200 with little automation. Why would the workload be hard by doing a go-around? Have done a few of them in both aircraft, with and without automation, don't really see the big issue. If the a/t was off during the approach and a go-around was required, by pressing the toga button, the flight director would give you go around mode. The rest is just basic flying, pitch up, you need thrust, no rocket science if you ask me....
I understand where you're coming from with your company own sop's, that's your company's decision. We follow Boeing as it is pretty much straight forward and you're covered.
I still fly the old -200's with the SP177's and the 727-200 with little automation. Why would the workload be hard by doing a go-around? Have done a few of them in both aircraft, with and without automation, don't really see the big issue. If the a/t was off during the approach and a go-around was required, by pressing the toga button, the flight director would give you go around mode. The rest is just basic flying, pitch up, you need thrust, no rocket science if you ask me....
I understand where you're coming from with your company own sop's, that's your company's decision. We follow Boeing as it is pretty much straight forward and you're covered.
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You've misquoted me. I didn't say the workload on a go-around is hard. I said it is increased, which is true of any aeroplane. When a manufacturer installs a system on an airliner to reduce pilot workload during a busy stage of flight why would you ignore it and intentionally reduce your overall working capacity?
Sadly the only answer I have experienced so far on the line is of feebly disguised macho-ism in an attempt to look "cool" in front of one's peers
"The rest is just basic flying, pitch up, you need thrust, no rocket science if you ask me...."
Turkish Airlines at Amsterdam. ThomsonFly at Bournemouth.
Sadly the only answer I have experienced so far on the line is of feebly disguised macho-ism in an attempt to look "cool" in front of one's peers
"The rest is just basic flying, pitch up, you need thrust, no rocket science if you ask me...."
Turkish Airlines at Amsterdam. ThomsonFly at Bournemouth.
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Sorry about the mis quote, my apologies. The go-around maneuver is not something new, it has been around for ages. With all this automation it seems to me, things are made far more complicated then actually necessary.
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With all this automation it seems to me, things are made far more complicated then actually necessary.
Turkish Air at AMS was a perfect example.
When SV started to acquire their L1011 aircraft, it was (at the time) the first truly automated airliner in service
Autoland, autothrust (very reliable), FMS with all the usual functions (the first one, actually, with full time engine thrust management) and the training department stressed that the 'automation' be used to the maximum extent possible.
However, when the FAA came to town to administer new type ratings for Captains, the FAA inspector did not want to see any automation used, with the exception of an autocoupled approach...they weren't interested in FMS functions, the inspector wanted to see...(shock, horror
) good old fashioned hand flying skills demonstrated.I knew a couple of these FAA guys rather well, and they were no-nonsense types that insisted that actual flying skills be maintained, no matter what.
My opinion?
They were absolutely correct.
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411A, I cannot agree more. I am against the pushbutton flying as well. The new generation seems to live with it. But watch them doing a go-around when all the automatics are off. (or just the A/T, for that matter).
Captaincy now consists of 4000 hrs watching crosshairs and an in dept knowledge of Part A, chapter 8 of the FCOM, among a few other things unrelated to flying.
Basic flying skills are not appreciated anymore. That is until an accident happens again. And again.
Captaincy now consists of 4000 hrs watching crosshairs and an in dept knowledge of Part A, chapter 8 of the FCOM, among a few other things unrelated to flying.
Basic flying skills are not appreciated anymore. That is until an accident happens again. And again.