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-   -   When to disconnect autopilot on approach (https://www.pprune.org/questions/527726-when-disconnect-autopilot-approach.html)

Killaroo 13th Nov 2013 16:44

When to disconnect autopilot on approach
 
A certain gent recently opined it was good airmanship to not disconnect the AP until in receipt of landing clearance. I've never heard of such tosh in my life before- but maybe I've spent 30 years flying in ignorance.
What say ye?

ahramin 13th Nov 2013 17:43

Pretty simple really. 1 out of 10 go-arounds leads to an unsafe situation, often due to non-existent manual flying skills.

So if you are an adherent to the "autopilot always on" school of thought and have trouble manually flying a go-around, airmanship would indeed dictate that you leave the autopilot on until cleared to land to reduce the risk of a botched go-around.

While I haven't seen a memo or SOP on this at my company yet, many instructors are already preaching this for landings at LGW because of the high number of GAs there. I think it's only a matter of time before this becomes part of many airline's SOPs.

Dash8driver1312 13th Nov 2013 18:08

When to disconnect autopilot on approach
 
I can understand the logic-well done on being so preachily close-minded and degrading in your rapid dismissal-but I do prefer to keep my hand in with manual flying.

I wonder how this person deals with situations when a tower advises to expect a landing clearance that may come after the MDA, or circling approaches?

You might find life better to try open discourse instead of kicking off on such an aggressive footing...good luck on your next CRM course!

flarepilot 13th Nov 2013 18:38

will someone tell me what "TOSH" is ?


we had ways of remembering landing clearance, but the best one and seemed most agreed upon was cleared to land, turn nose taxi/landing light on.

but we were and still are men and autopilots were and are for those who need them. (ops specs aside)

Piltdown Man 13th Nov 2013 18:57

Yes, it's tosh! Minimum A/P disconnection heights/altitudes are normally specified in AOMs, maximums are not specified. Therefore, disconnection should take place between cruise altitude and the minimum specified for the approach - a mixture of common sense and personal preference dictating exactly when. But when you next speak with said gent, you may wish to tell him that poor airmanship is restricting A/P disconnection until you are cleared to land.

GA_flps1 14th Nov 2013 07:48

On the 737ng boeing recommends 2-3nm out.

I prefer having the autopilot connected until the runway is clear, without the autopilot we're not allowed to use the A/T, and without the A/T I will have to set the GA thrust manually, why do more work than I get paid for? :E

172_driver 14th Nov 2013 09:31


On the 737ng boeing recommends 2-3nm out.
Where is that recommended?

GA_flps1 14th Nov 2013 09:58

Woops wrong should have been 1 to 2nm

FCTM rev11

When a manual landing is planned from an approach with the autopilot
connected, the transition to manual flight should be planned early enough
to allow the pilot time to establish airplane control before beginning the
flare. The PF should consider disengaging the autopilot and disconnecting
the autothrottle 1 to 2 nm before the threshold, or approximately 300 to 600
feet above field elevation.

galaxy flyer 14th Nov 2013 10:11

Reading this thread makes one wonder where in the heck piloting got to ths low state. Really, do we need an SOP and AOM guidance on flying the plane and use of the autopilot? Then, we have threads on lack of proficiency and low compensation. Well, there's your problem right there--if you require management guidance on basic flying (landing and go-arounds); don't expect much improvement.

172_driver 14th Nov 2013 10:16

GA_flps1,

Thanks, did not know such a recommendation existed that it was just another pilot's opinion.. :O

de facto 14th Nov 2013 10:24

I am with galaxy flyer on that one.
And to the OP,yes its utter tosh.

Jwscud 14th Nov 2013 10:46

Seems most of us ignore the FCTM then.

On a nice day at home base, it normally comes out at just before configuring. If it's miserable, leave it until youre stable and visual. Surely it's just a matter of common sense and airmanship?

Lord Spandex Masher 14th Nov 2013 10:54

Not really. "Should consider" isn't the same as 'must'.

Mind if I hand fly boss?

Do what you like, just don't do anything illegal or dangerous and don't crash.

Jwscud 14th Nov 2013 11:34

Indeed, though the way I read that FCTM excerpt is that it considers that 5-600' is EARLY.

It seems to be a bit of legalistic stuff to avoid MINIMUMS *click click* oh sh*t crunch rather than genuine advice on how to fly the aircraft. One or two of my colleagues have much earlier revisions of the FCTM which contain a lot more sensible stuff that seems to have been excised by the lawyers.

Killaroo 14th Nov 2013 16:38

Yes I do understand that at certain busy airports with complex Go Arounds it might make it simpler for the Children Of The Megenta Line to keep the Autopilot engaged until 'assured' landing is likely. Heck, why not just do an Autoland anyhow.
But, in truth, if I have to GA with the autopilot disengaged its not all that hard. Throttles up to TOGA, point it skyward, call FLAP, and GEAR UP.
Then you can reach over, push the AP PB and push heading for NAV.
Really tricky, eh?

con-pilot 14th Nov 2013 17:03

With me back when I was flying, 10,000 feet. Regardless of the type of approach.

But I'm from the old school of thinking, using the auto-pilot as an aid, not the primary operator of the flight contols for approachs and landings.

JeroenC 14th Nov 2013 18:15

On the NG single channel, the AP disconnects on GA....
Setting GA is done by PM, let him have some work!

DooblerChina 14th Nov 2013 23:42

LGW = 500'
MAN = base leg
Greek Island on a visual = 20000'+

Do whatever's comfortable, safe and sensible is the point I'm really trying to make...

High Energy 15th Nov 2013 20:37

I was actually thinking of this the other day and started to make a note of when I typically disconnect the autopilot and found it's between 1200-1000ft. So basically after my personal 'stable gate', even in VMC.

Also, in the last 6 months I have not come across one colleague who disconnected what some concieve as early, ie between FL100-3000ft. In the month prior to that I had one colleague who disconnected it at Fl150 to save the approach as it would have been bloody hard work to manage it with the a/p engaged. (ex bush pilot for what it's worth and he did a stunning job)

I do fly all my departures manually up to FL100 and are new to type/manufacturer.

A lot of the times, IMHO, you also benefit more from utilizing your a/p, a/t and situational awareness skills than from the manual handling part due to a challenging ATC or terrain enviroments. No mention of wx for obvious reasons.

Tu.114 16th Nov 2013 04:38

Horses for courses.

Of course, in marginal weather or with otherwise high workload, it is good practice to dump as much work on the computers as one possibly can. But with everything else in order, I do not hear "airmanship" call me to just observe the computers do what is in essence my job. Even more so as my type tends to restrict the use of the Autopilot in case of technical malfunctions: a single engine approach must be flown manually for example. So with non-critical visibility and ceiling, I consider it well advisable to use the opportunity for some hand flying as often as practical just to keep the skills ready and alive. In nice weather, I tend to switch the A/P and occasionally, situation permitting, as well the F/D off at 3000 to 6000ft.

As has been mentioned, the automatics are there to help and keep the workload at bay. They are not installed to substitute the pilots or to allow them to let their skills erode. I would therefore define airmanship with regards to automatics as "knowing how and when to use the systems capabilities while keeping ones personal skills honed".


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