ILS & Autothrottle

[Hamburg 2K8]

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.

[reivilo]

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 (http://ead-website.ead-it.com/publicuser/public/pu/registration.jsp)

good luck with all your flights on flightsim

[FCeng84]

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.

[BOAC]

Don't get too technical here, folks, this is a Flight Sim query.

[Sir Herbert Gussett]

Ha! Can this nonsense be moved to Spotter's Corner please.

[john_tullamarine]

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.

[Kiltie]

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.

[Maurice Chavez]

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.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.

[ClimbSequence]

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

[411A]

But it makes the manual flight very unstable
Hmmm, interesting.
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.

[galaxy flyer]

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

[Oakape]

The light on the IAS button is still on and switch is engaged.
What is the FMA indicating?

[grounded27]

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?

[ClimbSequence]

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.

[Kiltie]

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?

[Maurice Chavez]

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.

[Kiltie]

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 :yuk:

"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.

[Maurice Chavez]

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.

[411A]

With all this automation it seems to me, things are made far more complicated then actually necessary.
Not only that, but now we see more 'automation' accidents that one might expect.
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:ooh::ooh:) 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.:ok:

[latetonite]

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.

[Kiltie]

Yawn.

What an utterly, utterly cliched, blinkered, patronising and offensive view of others. Has it not occurred to you that there are a significant number of pilots out there who have perfectly adequate basic raw flying skills bred from varied backgrounds? However, rather than sit in an ivory tower of self-admiration of their basic handling skills, these systems are switched on, manipulated and understood by many more pilots than you give credit for. You may consider this a "dull" approach to flying, but personally I don't haul fare paying passengers around for an opportunity to show off how fantastic my basic poling skills are.

I hold a professional colleague in just as much high regard as a pilot for knowing the do's and don'ts of his company Part A book as I do for his good standard of automatic OR manual flying. We work in a rule based industry. I'd rather go to work with a compliant, average Joe pilot than a maverick out for the day to show off (without my invitation) how he can cope without automatic assistance. Leave that for the recurrent training environment.

[Centaurus]

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?

I think you miss the point. First of all, the manufacturer (Boeing) test pilots put a lot of thought into their recommended procedures and this includes checklist design. Among other factors previous accidents and incidents are studied and where applicable the lessons learned from these are incorporated into the recommended procedures.

Rubbishing a manufacturer's recommended procedure is a risky legal procedure. Interestingly, few operators who take it upon themselves to change the manufacturer's procedure, have the courage of their convictions to contact Boeing with the results of their measured trials to prove the manufacturer's test pilot recommendations were wrong. In any case, few operators are going to employ the Human Factors experts and associated qualified test flying personnel that would be required to challenge the manufacture's own experts.

The reasons why, for instance, Boeing (737 series) recommend manual throttle use (autothrottle disengaged altogether) with certain areas of manual flight, may not necessarily be explained in full detail in the FCOM or FCTM. It would triple the size of some manuals if detailed reasons were given for and against certain procedures.

On the other hand, it also explains why some operators are perfectly happy to disregard a manufacturer's recommended procedure and change it to suit the whims of whoever calls the shots in the airline. And that is because they can only hazard a guess at why the manufacturer recommends a certain procedure without amplifying the reason.

If the operator or pilot decides to disregard the manufacturer's recommendation it is on his own head. But if something should go wrong then the legal eagles are waiting to pounce.

The other thing to remember, is that automation dependancy invariably affects those pilots who lack the training or pure flying ability to switch seamlessly from automatics to manual flight. Recent loss of control in IMC accidents attest to that. With more and more cadet pilots going into the right hand seat and trained primarily as autopilot monitors rather than as airmen, one is left with the perception that a perfectly normal manual go-around with no FD or autothrottle, turns into a non-normal event that becomes quite frightening to someone unused to hand flying.

It shouldn't be like that of course, but it happens. The crutch of the automatic go-around even on a visual approach is relied upon as a life saver by some. Bloody sad - but true. I doubt if that will ever change.

The high-lighted original quote, re straight arm go-arounds, would suggest the author has had an unfortunate experience with a normal manually flown go-around. More simulator training needed, methinks:ok:

[411A]

More simulator training needed, methinks
Quite likely that won't happen....costs far too much.
So, expect the same sort of automation-induced accidents/incidents...perhaps even more.:yuk:

The only thing that is likely to change this unfortunate picture is for the concerned regulatory authority to say....enough is enough, and lay down the law....IE: train to proficiency.

[reivilo]

Quoted from my company Operations Manual:

Policy on the use of autopilot, autothrottle, FD

Levels of automation

The following levels of automation are defined:
- first level: no automation
- second level: use of flight director while hand flying
- third level: use of autopilot and auto throttle in its basic modes (alt. hold, lvl change, vertical speed, hdg sel., ...)
- fourth level: use of autopilot and auto throttle in flight management modes (LNAV/VNAV)

Flight crew must remain competent to use all levels of automation.

This last sentence leads to a very nice mix of flying departures and approaches in all these levels of automation and keeps us current. Depending on the weather/traffic situation most of flightcrew adapt easily to other levels of automation. Altough this is the first company that I work for, I like it this way.
No captain looks odd at me when I ask if he is OK if I fly a raw data departure or approach from 10.000ft in CAVOK weather. From some I hear that I can be surprised when I would also do this in other (especially british) companies.

[rudderrudderrat]

Preventing our manual flying skills from diminishing is important as this Flight Safety Foundation pdf (http://flightsafety.org/asw/jul10/asw_jul10_p30-34.pdf) points out. I would have agreed with 411A last year - but our (British) company is now spending a couple of hours sim time on this one.

[safetypee]

Many arguments have been made both for and against use of autothrottle (A’T) in manual flight. In most cases tipping point is aircraft dependent and thus the manufacturer’s advice should be heeded.

Without such advice there are some general issues which IMHO point towards not using autothrottle.
Some installations tend to destabilise the aircraft in pitch (often overcome with experience, but beware unfamiliar conditions). Some older aircraft have a weak or no autopilot–A’T interface. IIRC older 737’s have no control mode interconnect, but the 1011 (for its age) has a good interface, i.e. height control was a function of combined pitch and speed input and not pitch then speed.
More recently auto-flight systems are optimised for combined use, thus manual flight with A’T must coordinate control requirements – akin to normal flight control. However, with excessive use of A’T and autopilot, this may be the only baseline for the pilot’s experience. Thus attempting to mimic the autopilot during manual flight might not lower workload or give consistent performance due to the differences between the autos and the human in the way they use sensors and inputs, e.g. use of rad alt, gain change with speed / configuration, and trim rate.

Other problems arise due to complacency in not scanning speed or mode change, e.g. a low approach aiming for a ‘short’ touchdown (A’T use to control speed accurately). The approach may drift slightly low or encounter a rising ground late in the approach, either triggering the A’T to retard. If unnoticed, and with correcting nose up pitch further reducing speed, the aircraft could be at risk to a nose-high, slow speed, and possibly hard arrival, even before the runway.

IMHO, use of autothrottle in manual flight is an indication of a more serious problem that pilots may ‘loose’ the ability to fly ‘stick and throttle’. This is not so much the physical skills which are taught from basic flying training, but an individual’s confidence in the ability to fly manually in all conditions; note the calls for more manual flight, but only in good conditions. This apparent lack of confidence could spread to the majority of flying; always use the auto-pilot. Also to other systems, leading to automation dependency – lack of confidence in one’s ability to cross check with simple calculations, rules of thumb, etc; always believe the computer – part of the SOP culture?

The industry might have to choose between using experienced pilots to ‘fly’ aircraft (the old view) and pilots who monitor technology and automation (a future view).
There are pitfalls and advantages in both extremes. A concern is that the future could be imposed on pilots with aircraft design, yet most pilots still want to choose.
I fear that any future choice may only be in the title of the job description, not a choice of how or when to use the A’T.

[galaxy flyer]

Good points, safety pee. I had about 10,000 hours before I touched an auto throttle plane, the old habits of having a power setting in mind every time I moved the throttles are deeply embedded. I just changed to a second type which doesn't have A/T, first leg, it was all about learning the power settings for different configs and speeds. Soon, I had a fuelflow setting for most situations. How many trained on autothrust have a power setting and throttle position in mind whenever in auto throttle mode?

GF

[Kiltie]

Centaurus

I've never had any incident or problem with manual throttle go-arounds, using the straight arm thrust setting technique. My argument for leaving the autothrottle armed for go-around is one based on enhanced capacity for the pilot, not that the pilot is assumed to be incapable of setting thrust manually.

I find your assumption that I require further simulator training in these methods both presumptious and offensive. It has always been my preferred operating method to give each of my colleagues the benefit of the doubt in their hand flying skills; sadly it would seem many contributors to this thread hold an extreme prejudice that anyone who maximises automation must have crap manual skills.