Flight Directors off for stall practice in the simulator.
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Flight Directors off for stall practice in the simulator.
It is well known there are operators who mandate that the flight directors must be on and programmed for all phases of flight. There may well be technical reasons for this depending on aircraft design. That said, it would be no surprise to some, that automation dependency also plays a significant part with those sort of company directives.
During type rating training in simulators the approach to stall and stall recovery is usually practiced. This includes during on final approach in the landing configuration where ground contact is a factor. The pre-flight briefing may include FCTM advice such as "Ensure the proper flight director modes are selected for the desired manoeuvre. If the FD commands are not to be followed the FD should be turned off. Do not use the FD commands during stall recovery. FD commands are not designed to provide guidance to a recovery or approach to stall or stall."
The QRH also states under Approach to Stall or Stall recovery, a Note which says "Do not use flight director commands during recovery."
Having now set the scene, the decision has to be made by the instructor whether or not to turn off the FD for the exercise. On the other hand, as it is likely that in real life the FD will already be on during the instrument approach during which a stall or approach to stall has occurred, maybe the FD should be turned off for the recovery? After all, Boeing advice is: "If the FD commands are not to be followed the FD should be turned off."
Some may argue that because a go-around will take place once the aircraft has recovered from the stall, the FD should remain on during the manoeuvre to provide pitch guidance for levelling out at the missed approach altitude, if the stall occurred in IMC. Their argument being that the pilot should avoid being distracted by un-programmed FD indications and that he should be able "look through" the FD needles to see the nose attitudes during stall recovery. While some pilots claim that they can "look through" the FD indications to see what is behind them, others claim they are seriously distracted trying to see behind the needles and prefer to turn off the FD as part of the recovery.
The catalyst for this post was a colleague who was given a "Fail" mark for requesting his PM to immediately switch off both FD's as part of the recovery from the approach to stall. The instructor was of the view the FD should be left on during the whole exercise since the pitch bar indication would serve as a reminder of the missed approach altitude. While that may be true, nevertheless the priority in such a situation is a proper appreciation of nose attitude during the recovery; particularly as GA thrust used where ground contact is a factor, would cause a strong pitch up change of trim and may even lead to a delayed stall recovery. This is where raw data instrument flying skills become paramount. As Boeing reiterates: "Do not use FD commands during recovery." This would suggest that in event of an inadvertent stall the FD should be switched off so that pilots are not seduced into following erroneous or inappropriate FD commands .
Comments appreciated.
During type rating training in simulators the approach to stall and stall recovery is usually practiced. This includes during on final approach in the landing configuration where ground contact is a factor. The pre-flight briefing may include FCTM advice such as "Ensure the proper flight director modes are selected for the desired manoeuvre. If the FD commands are not to be followed the FD should be turned off. Do not use the FD commands during stall recovery. FD commands are not designed to provide guidance to a recovery or approach to stall or stall."
The QRH also states under Approach to Stall or Stall recovery, a Note which says "Do not use flight director commands during recovery."
Having now set the scene, the decision has to be made by the instructor whether or not to turn off the FD for the exercise. On the other hand, as it is likely that in real life the FD will already be on during the instrument approach during which a stall or approach to stall has occurred, maybe the FD should be turned off for the recovery? After all, Boeing advice is: "If the FD commands are not to be followed the FD should be turned off."
Some may argue that because a go-around will take place once the aircraft has recovered from the stall, the FD should remain on during the manoeuvre to provide pitch guidance for levelling out at the missed approach altitude, if the stall occurred in IMC. Their argument being that the pilot should avoid being distracted by un-programmed FD indications and that he should be able "look through" the FD needles to see the nose attitudes during stall recovery. While some pilots claim that they can "look through" the FD indications to see what is behind them, others claim they are seriously distracted trying to see behind the needles and prefer to turn off the FD as part of the recovery.
The catalyst for this post was a colleague who was given a "Fail" mark for requesting his PM to immediately switch off both FD's as part of the recovery from the approach to stall. The instructor was of the view the FD should be left on during the whole exercise since the pitch bar indication would serve as a reminder of the missed approach altitude. While that may be true, nevertheless the priority in such a situation is a proper appreciation of nose attitude during the recovery; particularly as GA thrust used where ground contact is a factor, would cause a strong pitch up change of trim and may even lead to a delayed stall recovery. This is where raw data instrument flying skills become paramount. As Boeing reiterates: "Do not use FD commands during recovery." This would suggest that in event of an inadvertent stall the FD should be switched off so that pilots are not seduced into following erroneous or inappropriate FD commands .
Comments appreciated.
Last edited by Judd; 17th Jun 2018 at 06:13.
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The instructor involved sounds like one of those nit picking idiots we all encounter from time to time. What really matters is how the manoeuvre is flown and how controlled flight is restored without exceeding limitations.
Whether the flight director is ignored or switched off is really secondary and at best a discussion item. If it happened for real I suspect it would be at the bottom of the list of priorities.
I'm a TRE and would not award a fail simply because somebody chose to turn the flight director off.
Whether the flight director is ignored or switched off is really secondary and at best a discussion item. If it happened for real I suspect it would be at the bottom of the list of priorities.
I'm a TRE and would not award a fail simply because somebody chose to turn the flight director off.
Last edited by 763 jock; 17th Jun 2018 at 08:06.
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In defence, m'lud:
The exercise was stall recovery. Did I achieve that satisfactorily? Yes. Is there a company SOP about FD's ON/OFF? No. Therefore should that have any effect on the assessment of the manoeuvre? No. IMHO. (TRE). Sounds like personal opinion, and failing on that basis for a specified manoeuvre seems overly harsh.
Should PF, during the startle factor of a stall recovery, be giving priority to FD's ON/OFF? Debatable. Should a current pilot be able to control attitude without an FD? Yes. FD is OFF, stall is recovered, TOGA is pushed with MAA set, would not the FD reappear until ALT AQ? Should that cue be enough for the level off? Probably.
Surely a fail for such an item has an appeal to HOT?
The exercise was stall recovery. Did I achieve that satisfactorily? Yes. Is there a company SOP about FD's ON/OFF? No. Therefore should that have any effect on the assessment of the manoeuvre? No. IMHO. (TRE). Sounds like personal opinion, and failing on that basis for a specified manoeuvre seems overly harsh.
Should PF, during the startle factor of a stall recovery, be giving priority to FD's ON/OFF? Debatable. Should a current pilot be able to control attitude without an FD? Yes. FD is OFF, stall is recovered, TOGA is pushed with MAA set, would not the FD reappear until ALT AQ? Should that cue be enough for the level off? Probably.
Surely a fail for such an item has an appeal to HOT?
The instructor involved sounds like one of those nit picking idiots we all encounter from time to time. What really matters is how the manoeuvre is flown and how controlled flight is restored without exceeding limitations.
Whether the flight director is ignored or switched off is really secondary and at best a discussion item. If it happened for real I suspect it would be at the bottom of the list of priorities.
Whether the flight director is ignored or switched off is really secondary and at best a discussion item. If it happened for real I suspect it would be at the bottom of the list of priorities.
Yes, when back in a normal flight regime you can start paying more attention to clearances, altitudes and the like but that’s sugar frosting compared with handling the escape correctly.
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Is there a company SOP about FD's ON/OFF? No. Therefore should that have any effect on the assessment of the manoeuvre? No.
Catch 22, a wicked problem, depends on viewpoint, on which window we look through; there are rarely answers. e.g. is your glass half empty or half full?
A quibble with language (my window) is that the good advice to ‘look through’ the FD is a normal function implying a combination of attitude and FD, whereas in a stall we would wish pilots to ‘ignore’ the FD - focus on attitude, probably an even more difficult task than combination. How do you mentally reject an information display which in normal circumstances could be the dominant reference, but where with the effect of surprise and startle in an emergency the mind reverts to first learnt, most used, information.
This debatable point offers a potential alleviation for all parties to understand the issue and to debate the relative safety merits of situations. Thus a learning view, vice an examining pass/fail position, would highlight the importance of understanding the situation, particularly the precursors, what is important, and how to avoid the situation; and if unable, how to recover.
We are told with these types of problems to look at the bigger picture. So my half-full glass, emptied into a larger glass could be judged near empty - best bitter please. And if you are having this discussion in a bar you are clearly drinking with the wrong people.
Thus this ‘technical problem’ (actually philosophical and human) should be posed to management - the bigger picture; as a safety report, to the manufacturer and regulator for a wider view of policies, design, training, examining, mandates, and choice and use of procedures.
A quibble with language (my window) is that the good advice to ‘look through’ the FD is a normal function implying a combination of attitude and FD, whereas in a stall we would wish pilots to ‘ignore’ the FD - focus on attitude, probably an even more difficult task than combination. How do you mentally reject an information display which in normal circumstances could be the dominant reference, but where with the effect of surprise and startle in an emergency the mind reverts to first learnt, most used, information.
This debatable point offers a potential alleviation for all parties to understand the issue and to debate the relative safety merits of situations. Thus a learning view, vice an examining pass/fail position, would highlight the importance of understanding the situation, particularly the precursors, what is important, and how to avoid the situation; and if unable, how to recover.
We are told with these types of problems to look at the bigger picture. So my half-full glass, emptied into a larger glass could be judged near empty - best bitter please. And if you are having this discussion in a bar you are clearly drinking with the wrong people.
Thus this ‘technical problem’ (actually philosophical and human) should be posed to management - the bigger picture; as a safety report, to the manufacturer and regulator for a wider view of policies, design, training, examining, mandates, and choice and use of procedures.
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FDs should be switched off if they are not to be followed is a general suggestions. It is applicable for any planned situation like visual approach. Steep turns are not done in commercial aircraft. Stall is not a planned manoeuvre. Once the aircraft has stalled at lower altitude immediate memory items for recovery should be applied i.e. lowering the nose, application of required thrust etc. Pilot who is doing the recovery should have the knowledge that FDs don't provide unstall guidance and ignore and just fly the attitude. If it's not in the procedure why waste time switching off FDs? It's a serious event and should have a standard procedure.
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"Ignore the FD"
Easier said than done sometimes. I'd agree with the pilot in question. Turn off the FD. Fly the plane. Then worry about what the FD thinks about the FCU selections.
Easier said than done sometimes. I'd agree with the pilot in question. Turn off the FD. Fly the plane. Then worry about what the FD thinks about the FCU selections.
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So that we don't remove the 5 minutes per year of practice of raw data flying that airline pilots get?
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Do not use the FD commands during stall recovery.
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Ignore the FD"
Easier said than done sometimes.
Easier said than done sometimes.
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INDIGO
Surely FDs have nothing to do with recovery from stall and they can be confusing if one doesn't know that they are not to be followed. In TCAS immediate action is FDs off and it is mandatory for a different reason. In automatic TCAS you don't switchoff the FD. EGPWS is a memory item where you ignore FDs. Stall recovery also is a memory item and it doesn't contain action on FDs. In low level stall one doesn't know how much height will be lost. The immediate actions in a stall are reduction of a AoA, wing level, thrust as required, checking speed brakes in which the PF must do before doing anything else. Forgetting any of these can be fatal. Putting the nose below the horizon with FD on or off should not be a such big deal. You may be doing the approach with the bird and if switch off FD first it will reappear with TOGA then you again switch it off? Obsession with FD off which is not essential action can also become a distraction and make you forget something more critical to recovery.
Surely FDs have nothing to do with recovery from stall and they can be confusing if one doesn't know that they are not to be followed. In TCAS immediate action is FDs off and it is mandatory for a different reason. In automatic TCAS you don't switchoff the FD. EGPWS is a memory item where you ignore FDs. Stall recovery also is a memory item and it doesn't contain action on FDs. In low level stall one doesn't know how much height will be lost. The immediate actions in a stall are reduction of a AoA, wing level, thrust as required, checking speed brakes in which the PF must do before doing anything else. Forgetting any of these can be fatal. Putting the nose below the horizon with FD on or off should not be a such big deal. You may be doing the approach with the bird and if switch off FD first it will reappear with TOGA then you again switch it off? Obsession with FD off which is not essential action can also become a distraction and make you forget something more critical to recovery.
Last edited by vilas; 18th Jun 2018 at 05:40.
Pilot who is doing the recovery should have the knowledge that FDs don't provide unstall guidance and ignore and just fly the attitude. If it's not in the procedure why waste time switching off FDs?
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Then why it is not a memory item? All memory items are laid down procedures. Is it because the manufacturer is not capable of thinking like us? And about stall only the test pilot has actual experience. It may not be easy that is why we practice in the Sim. Switching off FD is helpful but not at the cost of mandatory actions. Flying accurately and not stalling in the first place appears simpler than recovery. Most stall incidents are because of poor flying.
Last edited by vilas; 18th Jun 2018 at 06:00.
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Originally Posted by Capt Pit Bull
We could always go a bit radical and fly the recovery as specified by the manufacturer.
Fairly pointless discussion about the FDs.
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“Failing” someone during trading is a good measure of a company’s training standards and the trainers within. It happens, but normally this is for repetitive gross handling errors, diabolical CRM, dreadful preparation. But a “fail” for asking for the FD’s to be turned off? This speaks volumes. As has been pointed out already, the FD should not be followed for a recovery because it will not give any useful information. It would also be reasonable to question its validity following a stall recovery. The only issue I could see is do you actually need to turn the things off as it would be better to concentrate on the recovery rather than flick switches.
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