A late-ish stabilisation
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ALAR, "Stabilized Approach", and cynics
Studying the industry's efforts in the ALAR [Approach and Landing Accident Reduction], and the evolving "stabilized approach" concept, you can find general agreement.
But a few years back, one analyst gave a paper that points-out some of the counter-intuitive perceptions mentioned above (eg, an active-PF might get a smooth touch-down from a very steep high speed turning "approach"). Here are excerpts from that observer's paper from '04:
= = = \/ = = = EXCERPT = = = \/ = = =
http://www.isasi.org/pg_seminar.html (Entire ’04 Proceedings ~ 10.6 MB pdf.)
Wischmeyer, Ed, “The Myth of the Unstable Approach”; ISASI 2004 Proceedings, Session IX, pp 152-5.
“... while unstable approaches may increase the risk of a bad landing outcome, that risk is still so low that the concept of unstable approach can only rarely, if ever, be meaningfully used in accident and incident causal analysis....”
“... bad landings ... were frequently observed from stable approaches, and good landings were frequently observed from unstable approaches — and these initial, poorly understood observations were unsettling....”
“... other phenomenon present ... “pilot involvement factor” ... if the pilot who was flying was highly involved in flightpath control, then appropriate skill and experience would be applied and the landing outcome would be successful regardless of approach stability. Conversely, if the pilot were inattentive or not completely in the loop, this state of low involvement could manifest itself in a bad landing outcome, regardless of the approach stability.
“... a go-around by at least 500 feet ... if the approach was not stable, those definitions effectively ended at 500 feet. Yet, ASRS data ... indicated that significant atmospheric effects would be encountered at 300 feet ... and below. The perturbations caused by these low-level atmospheric effects would affect landing outcome statistics but would be encountered regardless of approach stability....”
“... data ... show that statistics generated on approach are very poorly correlated with statistics generated on landing, if at all....”
“... Five sub-phases to replace approach and landing ... superficially ... grouping approach and landing ... groups flight sub-phases with greatly differing characteristics. The five sub-phases are listed below ... The goal of each sub-phase is to position the aircraft ...
Flight Sub-Phase
-- Outside the FAF -- Radio navigation ... or radar vectors.
-- Inside the FAF
-- Final visual alignment
-- Flare and touchdown
-- Rollout and turnoff
“... research suggests that more meaningful analysis may be possible if events are first sorted by kind of event (e.g., touchdown, using the five flight sub-phases), and secondarily by severity of outcome (excellent, acceptable, unacceptable, incident, accident).
“... a common misperception that incidents are precursors to accidents in the sense that if only one more event were present in an error chain, there would have been an accident ... However, incidents frequently had all the ingredients to be accidents, but a defense (in the sense of Reason’s model) mitigated the event. In the case of unstable approaches, it seems likely that the pilot involvement factor hypothesized above may be a common “defense” against adverse consequences of unstable approaches.”
= = = /\ = = = END excerpt = = = /\ = = =
But a few years back, one analyst gave a paper that points-out some of the counter-intuitive perceptions mentioned above (eg, an active-PF might get a smooth touch-down from a very steep high speed turning "approach"). Here are excerpts from that observer's paper from '04:
= = = \/ = = = EXCERPT = = = \/ = = =
http://www.isasi.org/pg_seminar.html (Entire ’04 Proceedings ~ 10.6 MB pdf.)
Wischmeyer, Ed, “The Myth of the Unstable Approach”; ISASI 2004 Proceedings, Session IX, pp 152-5.
“... while unstable approaches may increase the risk of a bad landing outcome, that risk is still so low that the concept of unstable approach can only rarely, if ever, be meaningfully used in accident and incident causal analysis....”
“... bad landings ... were frequently observed from stable approaches, and good landings were frequently observed from unstable approaches — and these initial, poorly understood observations were unsettling....”
“... other phenomenon present ... “pilot involvement factor” ... if the pilot who was flying was highly involved in flightpath control, then appropriate skill and experience would be applied and the landing outcome would be successful regardless of approach stability. Conversely, if the pilot were inattentive or not completely in the loop, this state of low involvement could manifest itself in a bad landing outcome, regardless of the approach stability.
“... a go-around by at least 500 feet ... if the approach was not stable, those definitions effectively ended at 500 feet. Yet, ASRS data ... indicated that significant atmospheric effects would be encountered at 300 feet ... and below. The perturbations caused by these low-level atmospheric effects would affect landing outcome statistics but would be encountered regardless of approach stability....”
“... data ... show that statistics generated on approach are very poorly correlated with statistics generated on landing, if at all....”
“... Five sub-phases to replace approach and landing ... superficially ... grouping approach and landing ... groups flight sub-phases with greatly differing characteristics. The five sub-phases are listed below ... The goal of each sub-phase is to position the aircraft ...
Flight Sub-Phase
-- Outside the FAF -- Radio navigation ... or radar vectors.
-- Inside the FAF
-- Final visual alignment
-- Flare and touchdown
-- Rollout and turnoff
“... research suggests that more meaningful analysis may be possible if events are first sorted by kind of event (e.g., touchdown, using the five flight sub-phases), and secondarily by severity of outcome (excellent, acceptable, unacceptable, incident, accident).
“... a common misperception that incidents are precursors to accidents in the sense that if only one more event were present in an error chain, there would have been an accident ... However, incidents frequently had all the ingredients to be accidents, but a defense (in the sense of Reason’s model) mitigated the event. In the case of unstable approaches, it seems likely that the pilot involvement factor hypothesized above may be a common “defense” against adverse consequences of unstable approaches.”
= = = /\ = = = END excerpt = = = /\ = = =
Taking away the technical pros and cons let me just say this type of tight visual approach by MD-80/B737/CRJ may be seen dozens of times per day at Spanish airports (other than MAD BCN AGP) where traffic permits. Seen it personally at PMI loads and loads of times during the less busy times. Done it myself (as pax) loads of times in the AVIACO DC-9 days. Yep, it's called FLYING!
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Mmmm
Hand Solo is exactly right, a BAe 146/RJ isn't a big jet; and therefore is much more forgiving. It has huge speedbrakes and of course much less momentum than a Boeing.
I am very surprised by a couple of posts here.
Flying is only as safe as it is today because these rules and profiles have evolved out of the analysis of hundreds of accidents and incidents, mainly since 1945. (These people may indeed work for NASA, Harry the Cod).
Surely a good pilot is one who uses their co-ordination and judgement to consistently fly the correct profile and thereby increasing his/her chances of achieving a successful outcome of the flight. There are reasons why you are selected and PAID to do that by the airline; it's safer, we make more money for my pension fund and kill fewer people.
During 9 years of military flying I saw many of those 'natural pilot' guys just get it slightly wrong once and they paid the price very soon afterwards; although thankfully killing only one person (other than themselves) rather than 148.
Would you be so content with a surgeon operating on you choosing to ignore the established medical protocols, but choosing instead keep his 'hand in' with the scalpel and laser ! ... 'well... I know it's not the safest way to do a heart bypass, but it seemed to work last time, and it really makes me feel as though I'm a much better surgeon '
Therefore, whilst there may be a place for it in extremis, if you need to prove to yourself how co-ordinated and natural pilot you are, with an inventive approach leading to a smooth touchdown; fly during the weekend in a rented 172, but please not with my wife and 15 month old daughter in the back.
MoT
PS: who is this Wishmeyer bloke, is that really an academic and peer reviewed research paper !
I am very surprised by a couple of posts here.
Flying is only as safe as it is today because these rules and profiles have evolved out of the analysis of hundreds of accidents and incidents, mainly since 1945. (These people may indeed work for NASA, Harry the Cod).
Surely a good pilot is one who uses their co-ordination and judgement to consistently fly the correct profile and thereby increasing his/her chances of achieving a successful outcome of the flight. There are reasons why you are selected and PAID to do that by the airline; it's safer, we make more money for my pension fund and kill fewer people.
During 9 years of military flying I saw many of those 'natural pilot' guys just get it slightly wrong once and they paid the price very soon afterwards; although thankfully killing only one person (other than themselves) rather than 148.
Would you be so content with a surgeon operating on you choosing to ignore the established medical protocols, but choosing instead keep his 'hand in' with the scalpel and laser ! ... 'well... I know it's not the safest way to do a heart bypass, but it seemed to work last time, and it really makes me feel as though I'm a much better surgeon '
Therefore, whilst there may be a place for it in extremis, if you need to prove to yourself how co-ordinated and natural pilot you are, with an inventive approach leading to a smooth touchdown; fly during the weekend in a rented 172, but please not with my wife and 15 month old daughter in the back.
MoT
PS: who is this Wishmeyer bloke, is that really an academic and peer reviewed research paper !
Last edited by miles offtarget; 19th Dec 2007 at 15:48.
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Miles, A4,
I would rather have the life of my kids in the hands of these stick and rudder guys than in the hands of guys who almost stall when autothrust/autothrottle are inop!
I would rather have the life of my kids in the hands of these stick and rudder guys than in the hands of guys who almost stall when autothrust/autothrottle are inop!
Ut Sementem Feeceris
Hello Sarah,
I think we are at cross purposes here. I totally agree that "stick and rudder", AP and A/THR off are a good idea - under the right circumstances (Qantas B747 at Bangkok being a goodexample of when not to do it.)
What we are talking about here is stable approaches. It is perfectly possible to fly a fully manual, raw data ILS to minima and be stable. What we are talking about here is a commercial jet making an approach, screwing up the profile which results in a low power / higher sink rate scenario from which there is very little room for manouver if it starts to go wrong big style.
So I would rather have my family flown around by someone who flies every approach stabilised - be it visual, IFR, Autopilot, Manual or Circling.
A4
I thought a dichotomy was the surgical removal of a Welshman! (Radio 4 - I'm sorry I haven't a Clue - Graham Garden)
4
I think we are at cross purposes here. I totally agree that "stick and rudder", AP and A/THR off are a good idea - under the right circumstances (Qantas B747 at Bangkok being a goodexample of when not to do it.)
What we are talking about here is stable approaches. It is perfectly possible to fly a fully manual, raw data ILS to minima and be stable. What we are talking about here is a commercial jet making an approach, screwing up the profile which results in a low power / higher sink rate scenario from which there is very little room for manouver if it starts to go wrong big style.
So I would rather have my family flown around by someone who flies every approach stabilised - be it visual, IFR, Autopilot, Manual or Circling.
A4
I thought a dichotomy was the surgical removal of a Welshman! (Radio 4 - I'm sorry I haven't a Clue - Graham Garden)
4
Last edited by A4; 19th Dec 2007 at 15:47.
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Have to agree with Harry, here.
'Numpty' about sums it up.
As for NASA...naw, they wouldn't have him.
'Numpty' about sums it up.
As for NASA...naw, they wouldn't have him.
Whilst I can not possibly offer my opinion, surely you guys are able enough to look at an aircraft on short final and think...'bloody hell he looks fairly unstable'.......followed by a cursory glance at the TCAS elevation.
Obviously what this chap saw from the holding point was slightly un-normal given the weather conditions, which prompted this post to query the SOP of the carrier concerned!
A bit harsh me thinks.....now go and stand in the corner...
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Anyone know where my company can purhcase one of those special TCAS's that can indicate when another aircraft is stabilized or not. Hey we can do like a.... yeah... a landing signal officer on an aircraft carrier and wave off the offending airman with maybe our special secret flare system stored in the marzel vane.
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Please don't get me wrong... my current aircraft (MD-11) has the highest approach speeds in the world, now that the Concorde's retired. I feel totally comfortable in always meeting stabilized approach criteria at 1000' in that beast.
And 95% of our approaches ARE to congested, big, ILS-equipped runways. But 5% are not. We've balled up, by my count, 110 million dollars worth of aluminum in Subic Bay in the last ten years.
My humble opinion (and the company is actually starting to come around to this): we need to keep our aviator tools sharp - even if they're constantly at the bottom of our toolbox. That means click it off - at least when there's no other excuse but laziness. And I mean click it off on downwind and fly it like you used to, back when skills were skills.
I'm just trying to make a feeble defense of a guy that looked a little wild on final. Remember - you only bend metal at zero radio altitude.......
And 95% of our approaches ARE to congested, big, ILS-equipped runways. But 5% are not. We've balled up, by my count, 110 million dollars worth of aluminum in Subic Bay in the last ten years.
My humble opinion (and the company is actually starting to come around to this): we need to keep our aviator tools sharp - even if they're constantly at the bottom of our toolbox. That means click it off - at least when there's no other excuse but laziness. And I mean click it off on downwind and fly it like you used to, back when skills were skills.
I'm just trying to make a feeble defense of a guy that looked a little wild on final. Remember - you only bend metal at zero radio altitude.......
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a landing signal officer on an aircraft carrier and wave off the offending airman
Huck
By the way things are right now airplanes should return to the 3 crew config... 1 System Admin Senior as captain + 1 System Engineer (the backup power user), the 3rd being a Lawyer.
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spot on huck
gone from a 737 (200) to a swept up 800. Used to enjoy visual approaches, Won't even touch them now, am i a better pilot? nope, button pushing idiot these days. Company SOP's litigate against one being able to actually fly
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From my own personal experience I would have to agree with Huck on this one.
Since converting on to a new 'all singing & dancing' type and having been told by the boss man not to do any visual's for the first 6 months, I was amazed at how poor my flying skills became.
After just 2 months of auto-pilot + auto-throttle, I carried out a required circling approach and couldn't fly for S**t even when leaving the A/T in.
The bottom line is 15+ years of hand flying an older similar size jet on tight visual approaches has counted for sweet nothing.
Now, when the weather is nice I force myself to fly it all manually. End of problem.
Since converting on to a new 'all singing & dancing' type and having been told by the boss man not to do any visual's for the first 6 months, I was amazed at how poor my flying skills became.
After just 2 months of auto-pilot + auto-throttle, I carried out a required circling approach and couldn't fly for S**t even when leaving the A/T in.
The bottom line is 15+ years of hand flying an older similar size jet on tight visual approaches has counted for sweet nothing.
Now, when the weather is nice I force myself to fly it all manually. End of problem.
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If you are lucky enough to be at a holding point in Honolulu as an operating tech crew, watching some Aloha Airlines B737 getting stabilised on finals is a bit of a spectacle to watch.....at what altitude?...I guess its open to how good one is good at estimating how high one is. The front seat view makes it even better....only if there is no incident/accident happening.
Have just read the airbus report into the Iberia Quito accident. As good a recommendation for stabilised approaches as you could ask for. As for the comments that the antics that precipitated the thread were the signs of a good stick & rudder pilot.....bull! Its just a sign of someone c0cking-up the approach & having to manoeuvre late to rectify it.
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Whilst a neat, tightly flown visual circuit, perhaps at a 'challenging' airfield, is all good professional stuff, what isn't is Stuka diving at the runway, engines unspooled, and crunching on, half way down. That is what some of these jokers are up to. I think that is what the originator of this thread was getting at.
This reminds me of the foggy morning at the holding point for 26L at Berlin Tegel. PanAm has won the 06:00 Le Mans start to be No 1, followed by BA, EuroBerlin, and TWA (during their brief appearance). The first inbound Clipper from Frankfurt calls visual left base over Alexandraplaz. Gosh! Anyway, the 727 duly appears out of the clag, violently correcting, PILES on, and vanishes into the murk, leaving a mushroom cloud of blue tyre smoke.
After a suitable interval, the lead Clipper at the holding point transmits:
"Thet you, Hank?"
"Yup."
"Anybody hurt?"
"Nope."
This reminds me of the foggy morning at the holding point for 26L at Berlin Tegel. PanAm has won the 06:00 Le Mans start to be No 1, followed by BA, EuroBerlin, and TWA (during their brief appearance). The first inbound Clipper from Frankfurt calls visual left base over Alexandraplaz. Gosh! Anyway, the 727 duly appears out of the clag, violently correcting, PILES on, and vanishes into the murk, leaving a mushroom cloud of blue tyre smoke.
After a suitable interval, the lead Clipper at the holding point transmits:
"Thet you, Hank?"
"Yup."
"Anybody hurt?"
"Nope."
Last edited by Georgeablelovehowindia; 20th Dec 2007 at 10:35.
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That means click it off - at least when there's no other excuse but laziness. And I mean click it off on downwind and fly it like you used to, back when skills were skills.
Flying skills today are reduced, in many cases, and especially with larger companies, to the lowest common denominator, and when these folks notice someone who actually can fly a short approach in a skilled manner, they many times throw up their hands in disbelief.
Should we be surprised?
Of course not, these 'observers' simply don't know any better.
And never learned.
Just make the suggestion of hand flying, for example, and see the panic that results.