737 Go around?

[galdian]

To all:

I'm presently on hols and away from my FCTM, my understanding has always been per Mr Boeing:

- as the 737 is often the first jet upgrade for a turboprop operator use the KISS principle, everything auto or everything manual as the ARM feature CAN be confusing;
- if you have had proper training and have proper understanding then use ARM as desired and if for some reason (winds, other factors) the ARM mode is not acting correctly then disconnect the A/T...as you would any other system that is not performing correctly.

I am not aware of anything in the FCTM that is more specific to different phases of flight, if I have overlooked or misunderstood something then my bad.

Cheers
Galdian.

[Gypsy]

The large Company I used to fly the 737 for, had so many people asking about this that they wrote to Boeing to ask. The answer was clear. Boeing would not recommend it.

[FlyingStone]

Since Boeing recommends and large majority of airlines are not deselecting SPD on approach, I guess there must be something to it...

Regards your points ref use of A/T in ARM mode could I ask the question another way:
- why have Boeing included the ability for the PF to de-select the Autothrottle into ARM mode if this function is (apparently) never to be used?
Surely the A/T automatically going into ARM mode as you describe could be wired as a function of the on/off switch and A/T computer and other associated system computer logics etc?

Boeing has included a lot of features on the 737 that you shouldn't use as per their recommendation: A/T with manual flight (except during takeoff, climb or go-around), G/S capture before VOR/LOC (before respective SB), etc.

Aviation as all other industries learns its mistakes as times goes by and sometimes manufacturer's brilliant ideas during aicraft design turn out not to be so brilliant, so some capabilities of the aircraft are not recommended to be utilised in order to prevent some nasty situation to develop.

[RAT 5]

The ARM mode is a carry over from B757/767 where it is a design feature, I think, unless dementia has crept up on me unannounced. It's been a few years since....
People then went to the B737 MCP and played with the buttons and found that an 'ARM type mode' could be created and it seemed to be providing the same function as on B757/767. So guys started doing it and some CP's found out about that. As they didn't fly too much, and had never flown B757/767 they did not understand it. The normal human reaction of a manager who does not understand something is to ban it, so they did.
They also went to Boeing and asked the question; to back up their banning, and came back with the 'does not recommend' answer. So the ban stayed.
Now that begs the question how it can become an SOP? The manufacturer AND their XAA have to approve a 'non-normal'.

Regarding some comments about safety features and why Boeing would not recommend them: Boeing has this fixed philosophy that manual flight = manual controls + manual thrust. "period." So they changed TCAS RA to disconnect the lot. Previously it was AP only and leave AT in. Good idea. Then the philosophy gurus reviewed this, noticed the discrepancy and instructed AT disconnect. Bad idea. Why disconnect a safety feature? What problem had ever been created during a TCAS RA using AT? If it ain't broke don't fix it. Even if you apply the "what if' risk assessment I can not think of an answer that would cause the AT to be thrown out. When I asked a Boeing TC the reply was the philosophical one. No other reason.
However, they also had no idea about selecting 'TA Only' during an Emergency Descent or any other performance related non-normal incident; only the engine out case. Perhaps their philosophy nerds need some rebooting.

[galdian]

Thanks all for your input - and patience, maybe time for this dinosaur to pull the pin.

You have a function that affords safety (alpha floor protection and G/A thrust).

You can train a pilot to cope with many potential problems through ground school/sim training however understanding the use of ARM mode is beyond the capabilities of current airline training systems and/or (so it seems) pilots.

The answer: ignore the ARM function, turn it off 100% of the time and lose the safety potential 100% of the time.

The amusing thing: what is the No 1. stated concern for ALL and EVERY airline...safety!
And turning off a feature such as ARM that affords safety??

Anyone get the contradiction?

I realise conformity (with understanding) to company SOP's is an important part of operations, don't understand why not asking "why" is such a feared thing.

Maybe people have to die (like Airbus A330, finally "maybe basic flying skills and commonsense have been eroded too far..." before Boeing realise they have safety features in the ARM mode - so why not train to use them?

Cheers all
Galdian

[galdian]

RAT 5
Missed your response before I posted, thanks for your history/background.

Will only take issue with one point (and this may well simply be the difference between "official Boeing" Vs "talking to the Boeing delivery pilot over a few beers...."type stuff:

- all auto or all manual, KISS for new operators/turboprop upgrades;
- understand the ARM function then use it, fill your boots.

Now what was that thing about - safety...

Cheers all
Galdian

[ManaAdaSystem]

Regarding some comments about safety features and why Boeing would not recommend them: Boeing has this fixed philosophy that manual flight = manual controls + manual thrust. "period." So they changed TCAS RA to disconnect the lot. Previously it was AP only and leave AT in. Good idea. Then the philosophy gurus reviewed this, noticed the discrepancy and instructed AT disconnect. Bad idea. Why disconnect a safety feature? What problem had ever been created during a TCAS RA using AT? If it ain't broke don't fix it. Even if you apply the "what if' risk assessment I can not think of an answer that would cause the AT to be thrown out

No, it's not a bad idea to take out the AT with a TCAS RA. If you get a descend RA with the AT in N1, you will very fast go into an overspeed situation. The AT will remain at N1 in this situation with no speed control.

[cosmo kramer]

Almost all of our aircrafts doesn't provide "minimum speed reversion" after G/S capture. Only some of the oldest ones provide that feature. So it seems Boing indeed removed "the feature" (or customer option). And worse you can't see it, as the A/T can still be deselected into ARM, so if you don't look in the manual, you won't know if your aircraft for the day has it or not.

Besides from that, the reason it's not recommended is most likely because it can be confusing when the throttle is armed and when not. If you do a VNAV approach, you HAVE to disengage the auto throttle completely.

So in a stressed situation, when flying a VNAV approach, a confused pilot might press TOGA without manually advancing thrust, and nothing happens!!

Better to keep uniform SOPs, so the pilot will always react the same, regardless of which type of approach is being flow. If you can't do a go-around with manual thrust, retraining is needed (badly)!

For the low speed scenario, Boeing invented the "airspeed low" GPWS call out. If that doesn't wake you up and cause you to advance thrust, you shouldn't be sitting in that seat either.

(...and I DO fly with ARM mode as it's SOP in my company).

[RAT 5]

For the low speed scenario, Boeing invented the "airspeed low" GPWS call out. If that doesn't wake you up and cause you to advance thrust, you shouldn't be sitting in that seat either.

Introduced after THY stall at AMS. So once again the solution/back-up is to insert another auto-function between pilot & a/c. As we seen over the years this only encourages, subtly, the pilot to reduce scan and rely on automatic warnings. Shades of SFX B777 and others. I suggest, strongly, that if THY had been a manual approach with manual thrust, and followed the exact same manoeuvre, they would not have stalled. Add to that the use of ARM, perhaps better. I've never been allowed to use it on B737 so can not comment on its function in reality. (Indeed, has anyone had it kick in the save their backside? or is it just a theory?)

No, it's not a bad idea to take out the AT with a TCAS RA. If you get a descend RA with the AT in N1, you will very fast go into an overspeed situation. The AT will remain at N1 in this situation with no speed control.

OK, true, if you are in a climb; but is it that critical? However, and I've seen it in the sim many times, they get a 'CLB CLB RA"; disconnect everything, apply 3g pull and forget to add power. Now do that at FL350 and see what the speed does. Is a low speed more/less critical than overspeed? One has a clacker the other a shaker & clacker. I've also seen the "DESC NOW RA + Increase ROD". Then "Clear of Conflict" = climb back to last cleared FL and forget to add thrust. Consequence? see above. IMHO on there balance of risks I'd rather keep AT engaged. Dogmatic philosophy has its weaknesses.

Regarding SAFETY and commonality of actions: agree. I know of some airlines that encourage maximum use of Automatics, at all times: yet they perform a single channel ILS or NPA with full automatics; make a G/A = AP disconnects, but AT remains engaged, but they fly the whole GA and flap retraction in manual with AT in engaged?????

[ManaAdaSystem]

Seriously?

OK, true, if you are in a climb; but is it that critical? However, and I've seen it in the sim many times, they get a 'CLB CLB RA"; disconnect everything, apply 3g pull and forget to add power. Now do that at FL350 and see what the speed does. Is a low speed more/less critical than overspeed? One has a clacker the other a shaker & clacker. I've also seen the "DESC NOW RA + Increase ROD". Then "Clear of Conflict" = climb back to last cleared FL and forget to add thrust. Consequence? see above. IMHO on there balance of risks I'd rather keep AT engaged. Dogmatic philosophy has its weaknesses.

There are no TCAS manouvers that require a 3 G pull. A manouve like that at FL 330 will be interesting, with or without thrust. It would be a FAIL and retake in my airline.
ANU = more thrust. Pretty basic, so if you many times have seen pilots who fail to understand this, then I suggest you may have a problem on your hands.
Maybe you should transfer them to Airbus?

[TheiC]

For the low speed scenario, Boeing invented the "airspeed low" GPWS call out. If that doesn't wake you up and cause you to advance thrust, you shouldn't be sitting in that seat either.

No, they didn't invent it. It was recommended by the Dutch Safety Board report. If I ever write a book on these topics you'll read its full story there.

Oh, and if it doesn't 'wake you up', you may be suffering inattentional deafness, which may affect anyone, so you seem to be saying that human pilots shouldn't fly the 737. Be careful what you wish for!

You have a function that affords safety (alpha floor protection and G/A thrust).

Leaving aside the philosophical challenge posed by 'affords safety', the feature has nothing to do with alpha floor, and the device which I prefer to use to apply go-around thrust, in the appropriate amount, at the right rate, is my right arm.

[galdian]

TheiC

Apologies if any confusion regards afford, certainly not meant in context of "affordable safety", perhaps "allow" would have been clearer.

In the go-around incident I mentioned it is indeed unfortunate your right arm was not there or quite clearly there would have been no incident.
Sadly your right arm was NOT there, the Captain applied insufficient power and an incident (almost accident) occurred which would NOT have happened had the A/T been in ARM mode. Fact!

Alpha floor - well if the A/T is disconnected and insufficient power set the aircraft will eventually stick shaker then stall if not corrected, if in ARM the power will come up BEFORE the stick shaker would activate thereby avoiding stick shaker and stall because the insufficient power setting has already been corrected.

Call me crazy but I'd call that Alpha Floor protection - possibly Boeing 737 style - but still protection which can improve (wait for it)...SAFETY!

Just a shame this system that allows SAFETY is too darned complex for the average knuckle-dragging pilot to understand!

Cheers all.

[framer]

and the device which I prefer to use to apply go-around thrust, in the appropriate amount, at the right rate, is my right arm.

Me too. That's why if I have a low level off from the miss I disconnect all automatics then carry out a manual go around.
This argument is really about pilots losing the ability to fly ( automation dependency ). If I was so overloaded that I I was at risk of not using thrust to fly my chosen airspeed to the level off then I certainly would not have the awareness to recognise that the level off is fairly low and make a conscious decision to fly it with the automatics out.
I agree with Theic about a pilot pulling 3G in a Tcas RA. I doubt any pilot in my airline has ever done that, even the ones known to struggle.
So if my assertion that at it's heart, this is a problem about automation dependency, is the answer rally to rely on automation more heavily? Or is it to provide an appropriate amount of manual flying training ?

[galdian]

framer
Don't quite see this is related to auto dependency, more about using a system in the standby mode that backs up the action of the PF to enhance safety.

That's certainly the case regards the alpha floor protection - it won't operate unless the PF has f**ked it up by not setting sufficient thrust - so it's about redundancy and safety.

We all have airports where different actions/procedures may be more appropriate - then you explain why, brief what functions you will/will not use, that's fine and all part of normal operations.
The question revolves around the 90-95% of flights where there are NO such consideration,

Disconnect a system that enhances safety.

Yeah - that really makes sense in this day and age, love to see THAT logic explained in a court of law after an incident/accident.

Cheers.

[TheiC]

Adding go-around thrust without pilot intervention in an aircraft with under-slung engines such as the B737 has terrible potential to take the pilot out of the loop, and the aircraft outside the envelope, in tens of seconds. Alpha floor, in an envelope-protected FBW aircraft, is completely different to that.

As to 'more manual flying training', I'm more concerned that, one assumes, we and our colleagues could all fly a go-around in our PA28s, C152s, etc. But at what point, and why, do some of us cease to be able to carry our that simple manoeuvre in larger aircraft? Is it because the aircraft is too complicated for human pilots below a certain calibre? Is it lack of practice? Is it too much training in OEI operations (far less likely and yet the regulatory requirement for years) and the significant difference in that procedure?

Finally, the common errors in AEO go-arounds are speed exceedences and level busts, both of which are good reasons not to use all the installed thrust for this exercise, most of the time, and metering the right amount is again easiest achieved without automatic assistance, in my experience.

Boeing did not intend the A/T to be used in the way some here are describing, and they've said so. The 737's flight deck is elegantly simple, in functional terms, and there are few things which can be misused. But misusing those few has consequences: I don't believe the guys who designed the CDU meant the scratchpad to be used for noting radio frequencies. So perhaps they didn't foresee the brief disappointment we feel when the aircraft tells us it can't go to 135.375ORTAC.

KISIC.

Keep it simple, intelligent colleagues. Simple doesn't only work for stupid.

[RAT 5]

Guys!! Don't take it too literally. 3G pull up was only to make the point that the more inexperienced pilots, in their panic, over control on the escape manoeuvre and pull, or push, way outside the safety red safety boundary indicator with both hands on the stick and nothing on the thrust levers. I hope that is all clear now.

[ManaAdaSystem]

Clear as crystal!
You have pilots who panic when they get a TCAS RA. Pilots who forget to use thrust when they start a climb.

[framer]

I'm with adasystem on that. A Tcas RA is not something that is met with panic in any airline I have flown for.

[neville_nobody]

The 737's flight deck is elegantly simple, in functional terms, and there are few things which can be misused

Yeah maybe if your last plane was an Ilyushin. A 777 is simple a 737 is not.

It can be mastered but it is not simple or easy by modern standards.

[Pin Head]

Good **** here guys, didn't realise my question would generate such passion.

Never seen deselect before until I flew with an American.

As I ve never seen it before can someone remind me the sequence of A/t and map selections just to clarify the chain of events.

On the basis of KISS, my European airline always says

Go around flaps 15 check thrust.

So PM after pF gas cautioned his drills,

Confirms the FMA, selects an actual flap position on PF request and confirms that two fat ladies, quack quack, 88% roughly is set.