BA762 report released (cowl doors openning)
if everyone did their jobs exactly by the book there would be delays and the airline would have to do something about it.
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When is a door not a door?
JohnFTEng asked yesterday -
'On most consumer appliances there is an interlock that prevents operation when casing is open. On a highly automated machine like an Airbus why is there nothing similar - Fan cowl unlocked > start-up inhibited?'
The answer seems to be that fan cowls are not doors, but structure (according to EASA). As long as they do not break under 150% of expected flight loads (bending is acceptable), 'the theoretical probability of failure is zero and does not need to be considered further.' (Report 1.18.1, page 81).
So, as the fan cowl is not a door, it can never be ajar - as every schoolboy knows
'On most consumer appliances there is an interlock that prevents operation when casing is open. On a highly automated machine like an Airbus why is there nothing similar - Fan cowl unlocked > start-up inhibited?'
The answer seems to be that fan cowls are not doors, but structure (according to EASA). As long as they do not break under 150% of expected flight loads (bending is acceptable), 'the theoretical probability of failure is zero and does not need to be considered further.' (Report 1.18.1, page 81).
So, as the fan cowl is not a door, it can never be ajar - as every schoolboy knows
The answer seems to be that fan cowls are not doors, but structure
Even if they had been certificated as doors, the requirements only state that they should be designed so that unlatching during flight from the fully closed/latched/locked condition is extremely improbable.
But that's not what happened here, of course.
Ref the possible manual thrust issues in this incident.
According to a current Airbus pilot, BA requirement is 777/787/Airbus pilots to practice manual thrust management once every three years in the sim. Not approved on route flying.
According to a current Airbus pilot, BA requirement is 777/787/Airbus pilots to practice manual thrust management once every three years in the sim. Not approved on route flying.
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Structure vs system
A little further on in the report (1.18.1, page 82) a definition of 'extremely improbable' is given as less than 1 in 1,000,000,000 per flight hour. This is the requirement for an aircraft 'system'. The experienced rate of fan cowl opening (Report 1.18.2, page 84) is 1 in 1.28 million flight cycles pre EASA AD F-2001-381 (hold open device) and 1 in 2.42 million after that AD. I don't know the average hours per A319/320/321 cycle but say it is about 2 hours, then the occurrence of fan cowls opening is about 200 times over the acceptable limit of a 'system' and it would be more of an issue.
In addition, if they were a system there would be a cockpit warning for unlatched cowls. However EASA reasoned that if you have a warning system you get false alarms
In addition, if they were a system there would be a cockpit warning for unlatched cowls. However EASA reasoned that if you have a warning system you get false alarms
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I've heard KLM and delta have started sending cadets up for acrobatics training. Seems a good idea
Virgin are apparently more flexible and allow airbus crews to use manual thrust at their discretion. It is increasingly worthwhile finding out an airlines SOPs before flying. Sad
To avoid other false warnings, to facilitate keeping to schedule, and to save fuel, I'd like to suggest that TAWS/EGPWS, TCAS, and smoke detectors be removed from commercial transport aircraft.
As I've mentioned before, there is a tried and tested way of completely eliminating the risk of unlatched cowlings causing damage in flight.
Please compare the foreground and background aircraft in the image below. One of these aircraft will never suffer damage due to an improperly latched cowling.
Depressing report. But maybe a useful reminder that fatigue is not only an issue for the folk in the front seats.
Structure vs system
The experienced rate of fan cowl opening (Report 1.18.2, page 84) is 1 in 1.28 million flight cycles pre EASA AD F-2001-381 (hold open device) and 1 in 2.42 million after that AD. I don't know the average hours per A319/320/321 cycle but say it is about 2 hours, then the occurrence of fan cowls opening is about 200 times over the acceptable limit of a 'system' and it would be more of an issue.
The difference being that certification requirements can't possibly mitigate against the effects of departing with unsecured cowls any more than they could against, say, an unsecured cabin door (albeit that the latter, of course, have warning systems).
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Porter (PD) #617 ? 06-Jul-2015 ? CYTZ - CYTS ? FlightAware
It doesn't have to be an Airbus either..this Porter aircraft returned safely after losing a cowling according to AV Herald.
It doesn't have to be an Airbus either..this Porter aircraft returned safely after losing a cowling according to AV Herald.
I've heard KLM and delta have started sending cadets up for acrobatics training.
Acrobatics is stuff like juggling, tightrope walking and trapeze.
Although given this sorry situation it might be worth giving it a go!
Last edited by Private jet; 16th Jul 2015 at 12:59.
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What is annoying with airline management putting restrictions on manual thrust is that the first rule of Airbus is that if you don't like what the automatics are doing, revert to manual flight. Management see the recommendation to use Autothrust in most circumstances (which is entirely logical) but ignore the necessity to be fluent in manual thrust flying because of a perception of risk.
The irony is, that the Airbus is very easy to fly in manual thrust/ap off, with all the protections there if you should be daft enough to cock it up.
The irony is, that the Airbus is very easy to fly in manual thrust/ap off, with all the protections there if you should be daft enough to cock it up.
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Last year at LHR I was on a 767 that had issues locking the cowling- they appeared to be trying to fix it with a hammer and swiss army knife
It did not look like a very robust or easy to use fitting TBH
It did not look like a very robust or easy to use fitting TBH
If you think an RB211 cowling is difficult to latch closed (and as I recall it usually wasn't) then you should have seen what the old JT9's were like! They never got left open or came open in flight though.
JohnFTEng asked yesterday -
'On most consumer appliances there is an interlock that prevents operation when casing is open. On a highly automated machine like an Airbus why is there nothing similar - Fan cowl unlocked > start-up inhibited?'
One more level of complication - well intended as it is = one or more failure modes that could affect propulsion.
'On most consumer appliances there is an interlock that prevents operation when casing is open. On a highly automated machine like an Airbus why is there nothing similar - Fan cowl unlocked > start-up inhibited?'
One more level of complication - well intended as it is = one or more failure modes that could affect propulsion.
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At the risk of starting another Boeing versus Airbus thread, I'd like to point out a pretty obvious design fault on the Airbus (though obv I stand to be corrected by engineers various)
The Airbus engines' doors just hang when unlatched. They fasten underneath and so it's very difficult to see when they're in that position.
Boeing's doors open differently and have to be fully in either position. They 'pop' semi-opened if not latched properly.
That's what I've been told anyway!
The Airbus engines' doors just hang when unlatched. They fasten underneath and so it's very difficult to see when they're in that position.
Boeing's doors open differently and have to be fully in either position. They 'pop' semi-opened if not latched properly.
That's what I've been told anyway!
One more level of complication - well intended as it is = one or more failure modes that could affect propulsion.
And anyway the AAIB's recommendation isn't for that, it's for an unlatched condition warning system, not one that commands an engine to shut down.
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cowl/start interlock
let's say you run into a flock of birds, or encounter icing severe enough to give a spurious cowl open indication........
you now can't start your engine should the need arise
you now can't start your engine should the need arise
manual thrust
If BA flt ops management think there is a risk involved with pilots operating manual thrust, then it is they, the management who have created that risk by not allowing pilots to practice when circumstances allow. Do they not appreciate just how easy and pleasant to fly these modern aeroplanes are, and that hand flying is both enjoyable and professionally rewarding.
Perhaps they should ponder how we coped on VC10s, 707s and 737-200 etc, etc., with NO autothrottle, (or a Canberra with not even an autopilot !!) we just got on with it and flew the damned things, and on the 75/76 when hand flying we were required to disconnect the AT !!.
...........and am I to believe that BA allows dispatch with u/s autothrust yet the pilots may not have flown with manual thrust lever operation for 3 years, as CessnaPete reports ??
Worrying.
Perhaps they should ponder how we coped on VC10s, 707s and 737-200 etc, etc., with NO autothrottle, (or a Canberra with not even an autopilot !!) we just got on with it and flew the damned things, and on the 75/76 when hand flying we were required to disconnect the AT !!.
...........and am I to believe that BA allows dispatch with u/s autothrust yet the pilots may not have flown with manual thrust lever operation for 3 years, as CessnaPete reports ??
Worrying.
Last edited by RetiredBA/BY; 16th Jul 2015 at 20:02.
...........am I to believe that BA allows dispatch with u/s autothrust yet the pilots may not have flown with manual thrust lever operation for 3 years ??
I will add that in the days when there was a usable in house BA intranet forum this whole topic was often the subject of lively debate (usually led by our Airbus colleagues). Management were consistent in voicing their belief that the current policy was a "good thing"
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Prior to the arrival of the A321, the use of manual thrust lever use on the Airbus Fleet was encouraged, when appropriate. There was a concern that with the longer body of the A321 a low speed event on approach would lead to a higher chance of a tail scrape on landing - a view borne out by the history of tail scrapes on the A321 of other operators. There was a heated debate with most of the trainers and line crew on one side and a few key managers on the other as to the future and how to should proceed with the introduction of the A321. The managers, with the typical "I've made my mind up now I will pretend to consult experts" approach decided they knew best, ignored all advice and went ahead with the ban on the use of A/T on the bus fleet.
A few years later the official line had changed and the management could now "prove" it was safer as they had had significantly fewer low speed events across the bus fleet since the introduction of this policy. It could be proven statistically. A poor argument at best as the stats will also conclusively prove that if you never fly there are zero low speed events and that is much safer. What the managers have actually done is mis-employ a little bit of NUTA; they noticed a problem, they understood the problem may lead to an increased likelihood of a tail scrape and they thought ahead and put in place a way to avoid the problem. All the time failing to understand that the use of manual thrust is not an inherently dangerous practice, but deliberately deskilling your pilot work force is.
Put another way, the managers identified a potential weakness in the skill set of their pilots and then decided to train IN that weakness. To deliberately re-enforce the potential failure, to strengthen the likelihood, following a failure of the system of a dangerously low speed event. A sim requirement for triennial currency? No substitute for daily competence. Surely by this flawed logic pilots should be banned from any form of manual flying.
A few years later the official line had changed and the management could now "prove" it was safer as they had had significantly fewer low speed events across the bus fleet since the introduction of this policy. It could be proven statistically. A poor argument at best as the stats will also conclusively prove that if you never fly there are zero low speed events and that is much safer. What the managers have actually done is mis-employ a little bit of NUTA; they noticed a problem, they understood the problem may lead to an increased likelihood of a tail scrape and they thought ahead and put in place a way to avoid the problem. All the time failing to understand that the use of manual thrust is not an inherently dangerous practice, but deliberately deskilling your pilot work force is.
Put another way, the managers identified a potential weakness in the skill set of their pilots and then decided to train IN that weakness. To deliberately re-enforce the potential failure, to strengthen the likelihood, following a failure of the system of a dangerously low speed event. A sim requirement for triennial currency? No substitute for daily competence. Surely by this flawed logic pilots should be banned from any form of manual flying.
Last edited by Juan Tugoh; 18th Aug 2015 at 08:22.