737 Go around?
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737 Go around?
P – Some companies advise the use of autothrottle in ARM mode on final approach with manual flight (except for gusty wind conditions). This mode offers protection to underspeed and offers automatic and accurate go-around thrust when TO/GA is pushed.
Can I ask why the latter?
Can I ask why the latter?
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Same as in an automatic go around one click commands thrust for around 1500 to 2000 fpm, the second click increases that to full go around thrust. The first option is usually enough and makes a go around quite a bit easier, especially with a low level off altitude.
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It's in ARM as a passive protection mode. If you press TOGA you are commanding it do something, so lo & behold it usually does it, by engaging.
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As Denti says: try to stay away from the 2nd click... Level bust will be the least of your problem in most of the cases if you use that. I used to prefer to do it by hand rather than by double clicking 
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Well, there is always the different double click: click once to go into go around mode, then click to disconnect the autothrottle and do a slow manual thrust increase. If terrain is not an immediate factor that makes for a much smoother go around.
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...but if you float on landing, doesn't the AT come in and help you fly down the runway at 10ft???
Its a long ago fuzzy memory to me now but I'm sure this was the reason Boeing don't recommend keeping the AT armed.
Its a long ago fuzzy memory to me now but I'm sure this was the reason Boeing don't recommend keeping the AT armed.
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Well, there is always the different double click: click once to go into go around mode, then click to disconnect the autothrottle and do a slow manual thrust increase.
Careful!! These are 2 very different clicks.
Then again; before you reply "that I know that," the original questioner might not understand your experienced comment. But then again, one click of TOGA gives you a very gentle manageable ROC, so why would you want to disconnect. This could bring about speed control at level off as your scan is diverted from the essentials. That is but one reason why, often, the normal all engine GA is messed up.
Careful!! These are 2 very different clicks.
Then again; before you reply "that I know that," the original questioner might not understand your experienced comment. But then again, one click of TOGA gives you a very gentle manageable ROC, so why would you want to disconnect. This could bring about speed control at level off as your scan is diverted from the essentials. That is but one reason why, often, the normal all engine GA is messed up.
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...but if you float on landing, doesn't the AT come in and help you fly down the runway at 10ft???
If I have the automatics in and a go around is needed with a level off less than 2000ft away, I disconnect the A/P and the A/T , then press toga and use the thrust I want. Works for me a bit nicer than leaving the A/T in.
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Couple of years ago a new/old "esteemed" Captain almost created a smoking hole doing a do-around after having disconnected the A/T (hello 1960's!) and not applying sufficient thrust, company "policy" to that point was ARM mode the 737 operation having been set up by those with substantial 737 experience.
Fortunately for the company the F/O was able to talk the Captain through the stuff up without the Captain losing "face"; just dumb luck, the right F/O in the right place at the right time, some would have been too conflicted by culture to have saved the day,
There are times when the ARM mode does NOT work (primarily gusty unstable winds) and is best disconnected, the question is not "when do you use ARM mode", the question should be "when would you NOT use ARM mode?"
Bit of groundschool, 10 minutes in the SIM and - as if by magic! - seeing is believing, all understood and everyone happy!
ARM mode is both an operational mode and a safety mode - why would you disconnect a safety mode if you don't have to?
And call me crazy but I don't believe "too lazy or too stupid" is a valid reason in 2015 - you'll have to do better than that please!
Finally for the "flat earthers" out there who reckon ARM is white man magic and should never, ever be used: why would Boeing waste time and money on a feature (yes again a SAFETY feature) if it's never, ever to be used??
I thought it was only Airbus who were that way inclined at times!
Fortunately for the company the F/O was able to talk the Captain through the stuff up without the Captain losing "face"; just dumb luck, the right F/O in the right place at the right time, some would have been too conflicted by culture to have saved the day,
There are times when the ARM mode does NOT work (primarily gusty unstable winds) and is best disconnected, the question is not "when do you use ARM mode", the question should be "when would you NOT use ARM mode?"
Bit of groundschool, 10 minutes in the SIM and - as if by magic! - seeing is believing, all understood and everyone happy!
ARM mode is both an operational mode and a safety mode - why would you disconnect a safety mode if you don't have to?
And call me crazy but I don't believe "too lazy or too stupid" is a valid reason in 2015 - you'll have to do better than that please!
Finally for the "flat earthers" out there who reckon ARM is white man magic and should never, ever be used: why would Boeing waste time and money on a feature (yes again a SAFETY feature) if it's never, ever to be used??
I thought it was only Airbus who were that way inclined at times!
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All good stuff guys, keep the debate going.
As per the manual, Boeing recommends a/t out as well as A/p. I have always done that and call go around flaps 15 check thrust. The last two words always cover me.
It was only flying with some Americans that I saw this arm thing. As its not in the manual I questioned the rationale for doing it.
Denti be careful with these double clicks. If you have left the auto throttle in for Ga and then take out the a/t once the go around has been established sounds like a recipe for disaster. Completely non Boeing and truthfully would create organised confusion to the other guy!
As per the manual, Boeing recommends a/t out as well as A/p. I have always done that and call go around flaps 15 check thrust. The last two words always cover me.
It was only flying with some Americans that I saw this arm thing. As its not in the manual I questioned the rationale for doing it.
Denti be careful with these double clicks. If you have left the auto throttle in for Ga and then take out the a/t once the go around has been established sounds like a recipe for disaster. Completely non Boeing and truthfully would create organised confusion to the other guy!
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why would Boeing waste time and money on a feature (yes again a SAFETY feature) if it's never, ever to be used??
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So when exactly does Boeing say the ARM mode SHOULD be part of ANY SOP??
Not sure it's stated anywhere - but happy to be corrected.
If correct then the use of ARM is only restricted by your imagination - or lateral thought, a thing too often lacking in todays society IMHO:
- Push TOGA in a go-around and (if in ARM) 1st stage power is applied - therefore avoiding the very incident I mentioned of applying insufficient thrust at a time of high workload;
- leave in ARM on a dark and stormy 600' low vis circling approach and (after politely pointing out to the individual they are getting too slow) if uncorrected will apply power to avoid stickshaker and/or stall.
Using features that increase safety to....increase safety, interesting concept. When will such lunacy end??
And please - anyone - do not try and misquote Mr Boeings words against him - use of ARM not NORMALLY recommended as KISS principle for new jet operators; everything manual or everything auto.
With proper training and understanding - fill your boots (as I've done for over 26 years.)
Finally same question applies - why would Boeing bother with a function that is never, ever to be used??
Not sure it's stated anywhere - but happy to be corrected.
If correct then the use of ARM is only restricted by your imagination - or lateral thought, a thing too often lacking in todays society IMHO:
- Push TOGA in a go-around and (if in ARM) 1st stage power is applied - therefore avoiding the very incident I mentioned of applying insufficient thrust at a time of high workload;
- leave in ARM on a dark and stormy 600' low vis circling approach and (after politely pointing out to the individual they are getting too slow) if uncorrected will apply power to avoid stickshaker and/or stall.
Using features that increase safety to....increase safety, interesting concept. When will such lunacy end??
And please - anyone - do not try and misquote Mr Boeings words against him - use of ARM not NORMALLY recommended as KISS principle for new jet operators; everything manual or everything auto.
With proper training and understanding - fill your boots (as I've done for over 26 years.)
Finally same question applies - why would Boeing bother with a function that is never, ever to be used??
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Go around flaps 15 Check thrust
Those last two words cover the need not to use Arm in my view.
If he or she can't manually set an N1 target of day 88% ( two fat ducks, bingo speak) then I would scratch my head
Those last two words cover the need not to use Arm in my view.
If he or she can't manually set an N1 target of day 88% ( two fat ducks, bingo speak) then I would scratch my head
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...but if you float on landing, doesn't the AT come in and help you fly down the runway at 10ft???
Denti be careful with these double clicks. If you have left the auto throttle in for Ga and then take out the a/t once the go around has been established sounds like a recipe for disaster
The discussion about the use of the ARM mode is very old, but apparently some airlines use it and it doesn't cause smoking holes. Personally i used it during my stay on the 737 for about 15 years in several carriers that had it as their SOP and it has some advantages and some disadvantages, but nothing that cannot be trained for.
A while since I flew the 73, but when I did, Boeing recommended against doing approaches in ARM because of the possibility of uncommanded thrust movement during flare and landing.
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Galdian, Boeing specifically recommends against using A/T ARM during manual approach and landing. Other phases of flight according to normal automation SOPs. Therefore, A/T ARM mode is SOP for takeoff (prior to TOGA and after THR HOLD), and idle thrust descent with A/P engaged.
Yes, some airlines include it in their SOP's, in specific defiance of Boeing's recommendations, because they think they know better. That's up to them. Other airlines fly in accordance with the manufacturer's recommendations, including mine which is one of the oldest airlines in the world.
The only near-smoking hole involving a normal go-around I've read about in recent times was in your (and my) country and it was caused by an operator varying it's SOP's in specific defiance of Airbus's recommendations, because they thought they knew better.
Yes, some airlines include it in their SOP's, in specific defiance of Boeing's recommendations, because they think they know better. That's up to them. Other airlines fly in accordance with the manufacturer's recommendations, including mine which is one of the oldest airlines in the world.
The only near-smoking hole involving a normal go-around I've read about in recent times was in your (and my) country and it was caused by an operator varying it's SOP's in specific defiance of Airbus's recommendations, because they thought they knew better.
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Gypsy
Please quote Boeing FCTM correctly:
"...do not NORMALLY recommend...."
Derfred
the almost "smoking hole" was in a smaller company in Asia in January almost 3 years ago, didn't make global news as the smoking hole was (only just) avoided so merely an incident for local and company information.
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?
Why is the tempting (well for me at least) button there on the MCP acting like an aviation siren and whispering "deselect, deselect" so seductively??
Cheers
Please quote Boeing FCTM correctly:
"...do not NORMALLY recommend...."
Derfred
the almost "smoking hole" was in a smaller company in Asia in January almost 3 years ago, didn't make global news as the smoking hole was (only just) avoided so merely an incident for local and company information.
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?
Why is the tempting (well for me at least) button there on the MCP acting like an aviation siren and whispering "deselect, deselect" so seductively??
Cheers