Landing gear down and segments?
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latetonite:
If my airplane, on two engines, would be unsafe to fly with the gear down, regarding obstacles, I would also not attempt this departure with the gear up.
If my airplane, on two engines, would be unsafe to fly with the gear down, regarding obstacles, I would also not attempt this departure with the gear up.
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It would not be safe to simply decided to raise the gear in response to an engine failure, as you would have already lost performance, and gear retraction is often a high drag sequence.
Gear is ALWAYS raised in a response to an engine failure. That is what the first segment is there for.
Takeoff calculations only deal with engine failures at ONE specific point in time: V1.
If your engine fails before V1, you stop obviously. If it happens AFTER V1, you have gained performance - not lost performance.
If my engine fails at 200 feet altitude, I had 200 feet more altitude gain with all engines operating. If I forgot to retract the gear for some reason, obviously I would do it at this point to prevent carrying a loss of performance further into the departure (now my engine failure contingency procedure, not the SID).
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tullamarine
I said play it by ear and I meant it. So, here you go. YOU takeoff in a twinjet and both an engine failure happens and you happened to forget to remove the gear pins and YOU CANNOT retract the gear.
Do you open up your emergency checklist and follow the ENGINE OUT GEAR UNABLE TO RETRACT PROCEDURE ...TAKEOFF
(lots of luck)
Or do you figure something out right away?
Beirut pilot. I have a feeling you think we keep the gear down to cool things off all the time. Like I mentioned, if you were in the pattern doing multiple landings, full stop with brakes as in a training situation, even DP Davies, the brilliant author of "HANDLING THE BIG JETS" indicates you might keep the gear down to cool it off in the traffic pattern.
But as others have indicated, you wouldn't leave the gate, or the ground if you knew the brakes were "TOO HOT"".
IF you had rejected a takeoff and the brakes were HOT, there is a brake cooling schedule provided to the pilot to allow the brakes to cool down PRIOR to another takeoff attempt. THE idea is that on the next takeoff attempt you might have to REJECT that takeoff too. And you need the brakes cool in order to achieve stopping distance. Some types of brakes are less in need of cooling, but that is each type of plane to consider and not a generality.
So, again, we rarely if ever do what you think we do. Training is the only situation you might consider to leave the gear down (mind you, if there is an overheat or fire in the wheel well you might need to lower the gear, but that is a different animal)>
good luck
I said play it by ear and I meant it. So, here you go. YOU takeoff in a twinjet and both an engine failure happens and you happened to forget to remove the gear pins and YOU CANNOT retract the gear.
Do you open up your emergency checklist and follow the ENGINE OUT GEAR UNABLE TO RETRACT PROCEDURE ...TAKEOFF
(lots of luck)
Or do you figure something out right away?
Beirut pilot. I have a feeling you think we keep the gear down to cool things off all the time. Like I mentioned, if you were in the pattern doing multiple landings, full stop with brakes as in a training situation, even DP Davies, the brilliant author of "HANDLING THE BIG JETS" indicates you might keep the gear down to cool it off in the traffic pattern.
But as others have indicated, you wouldn't leave the gate, or the ground if you knew the brakes were "TOO HOT"".
IF you had rejected a takeoff and the brakes were HOT, there is a brake cooling schedule provided to the pilot to allow the brakes to cool down PRIOR to another takeoff attempt. THE idea is that on the next takeoff attempt you might have to REJECT that takeoff too. And you need the brakes cool in order to achieve stopping distance. Some types of brakes are less in need of cooling, but that is each type of plane to consider and not a generality.
So, again, we rarely if ever do what you think we do. Training is the only situation you might consider to leave the gear down (mind you, if there is an overheat or fire in the wheel well you might need to lower the gear, but that is a different animal)>
good luck
Moderator
It is usually detailed in the MEL OPS proc for Main gear inop( Airbus) . It indicates that specific Perf has to be done
A most important point. MEL applies to INTENTIONAL operation with a U/S.
The Design Standards still must be observed, hence most MELs include additional restrictions to address whatever the U/S might compromise in the way of the Standards.
In this case, performance still requires OEI segment capability .. hence the usual significant weight delta.
Doesn't seem to be any reference for the test pilots to just leave them hanging because they cooked the brakes
A specific FT consideration when playing with accel stop activities. Not relevant to routine line operations.
The point was that the rest of the world pretty much adopted the US certification specifications
.. but with significant differences in philosophy as becomes clear should you read and compare.
Our take off calculations are taking into account engine out
Precisely .. and that ALWAYS includes OEI segmented obstacle clearance considerations.
For a normal take off (with gear down as the example of the original poster), segment compliance is absolutely not an issue, nor a requirement.
Absolutely not so.
Should you INTEND to leave the gear down - doesn't matter what the reason might be - then the operation falls into the realm of MEL considerations. One MUST incorporate a weight penalty, and whatever else may be relevant to the Type, to address the normal OEI segmented takeoff exercise .. this time around, with the gear down.
The AFM defines what a normal takeoff might be, not the pilot on the day.
there are no segments in a normal takeoff
Again, not so. The AFM defines how you should be conducting the actual takeoff for whichever of AEO and OEI applies on the day .. recalling that any given takeoff will involve one or both ... Both are considered as an each time exercise and one or the other will dictate the limiting case for the RTOW calculation.
The overall inference, of course, is that the AEO procedure keeps the aircraft flight path above the OEI gross path.
they set the standards for what they considered to be a safe clearance of obstacles for design of instrument procedures.
.. and of no relevance to takeoff ..
An aircraft that does 15-20% climb gradient all engines operating, will have no problems making a 3.3% gradient with the gear extended.
Providing that the handling procedure is appropriate .. but of no relevance for OEI considerations.
Takeoff calculations only deal with engine failures at ONE specific point in time: V1
.. for the AFM calculation. The inferred responsibility on the operator/pilot is that the aircraft, AEO, will be operated in a manner which doesn't compromise a post-V1 failure. This can get a bit complicated if the takeoff requires turn(s).
The operator/pilot is responsible for making sure that the takeoff can get to an appropriate terrain clear point for a failure at any point during the process ..
YOU takeoff in a twinjet and both an engine failure happens and you happened to forget to remove the gear pins and YOU CANNOT retract the gear.
Fortunately, I haven't been in that situation ... although a mate was years ago on the F27 .. didn't seem to hurt his career as he ended up a successful and, by all accounts, a good checkie.
Seriously, though ..
(a) the Design Standards don't have regard to incompetence
(b) .. nor multiple significant failures
In the situation you posit .. the pilot could be in really serious strife, depending on the nature of the aerodrome on the day.
Or do you figure something out right away?
I suggest that most competent commanders will have armchaired that sort of scenario (gear retract failure) and have at least a generic plan. For difficult terrain runways in a commercially rational world .. there are some situations which are best handled by not getting out of bed that morning ...
A most important point. MEL applies to INTENTIONAL operation with a U/S.
The Design Standards still must be observed, hence most MELs include additional restrictions to address whatever the U/S might compromise in the way of the Standards.
In this case, performance still requires OEI segment capability .. hence the usual significant weight delta.
Doesn't seem to be any reference for the test pilots to just leave them hanging because they cooked the brakes
A specific FT consideration when playing with accel stop activities. Not relevant to routine line operations.
The point was that the rest of the world pretty much adopted the US certification specifications
.. but with significant differences in philosophy as becomes clear should you read and compare.
Our take off calculations are taking into account engine out
Precisely .. and that ALWAYS includes OEI segmented obstacle clearance considerations.
For a normal take off (with gear down as the example of the original poster), segment compliance is absolutely not an issue, nor a requirement.
Absolutely not so.
Should you INTEND to leave the gear down - doesn't matter what the reason might be - then the operation falls into the realm of MEL considerations. One MUST incorporate a weight penalty, and whatever else may be relevant to the Type, to address the normal OEI segmented takeoff exercise .. this time around, with the gear down.
The AFM defines what a normal takeoff might be, not the pilot on the day.
there are no segments in a normal takeoff
Again, not so. The AFM defines how you should be conducting the actual takeoff for whichever of AEO and OEI applies on the day .. recalling that any given takeoff will involve one or both ... Both are considered as an each time exercise and one or the other will dictate the limiting case for the RTOW calculation.
The overall inference, of course, is that the AEO procedure keeps the aircraft flight path above the OEI gross path.
they set the standards for what they considered to be a safe clearance of obstacles for design of instrument procedures.
.. and of no relevance to takeoff ..
An aircraft that does 15-20% climb gradient all engines operating, will have no problems making a 3.3% gradient with the gear extended.
Providing that the handling procedure is appropriate .. but of no relevance for OEI considerations.
Takeoff calculations only deal with engine failures at ONE specific point in time: V1
.. for the AFM calculation. The inferred responsibility on the operator/pilot is that the aircraft, AEO, will be operated in a manner which doesn't compromise a post-V1 failure. This can get a bit complicated if the takeoff requires turn(s).
The operator/pilot is responsible for making sure that the takeoff can get to an appropriate terrain clear point for a failure at any point during the process ..
YOU takeoff in a twinjet and both an engine failure happens and you happened to forget to remove the gear pins and YOU CANNOT retract the gear.
Fortunately, I haven't been in that situation ... although a mate was years ago on the F27 .. didn't seem to hurt his career as he ended up a successful and, by all accounts, a good checkie.
Seriously, though ..
(a) the Design Standards don't have regard to incompetence
(b) .. nor multiple significant failures
In the situation you posit .. the pilot could be in really serious strife, depending on the nature of the aerodrome on the day.
Or do you figure something out right away?
I suggest that most competent commanders will have armchaired that sort of scenario (gear retract failure) and have at least a generic plan. For difficult terrain runways in a commercially rational world .. there are some situations which are best handled by not getting out of bed that morning ...
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they set the standards for what they considered to be a safe clearance of obstacles for design of instrument procedures.
.. and of no relevance to takeoff ..
.. and of no relevance to takeoff ..
This example won't kill you, if you do not comply, but will get you into trouble with the air traffic controller.
Replace "due to airspace structure" with "due to mountain in departure path", and you get into more serious trouble. And it might not even limit you in your takeoff (engine out) calculations, as the SID might take you OVER the mountain and your engine failure procedure might take you in another direction with no significant obstacles.
In the example of Cologne, you have 3815 meter (12516 feet) runway. SO your takeoff performance calculations might give a result with so much derate/assumed temperature thrust reduction, that you are unable to met the 15.2% climb requirement for all engines operating.
This is from experience, not assumption. In this case you have to select MORE thrust to comply with the SID, than required for the engine out procedure. Your performance calculations won't warn you of this, as the software doesn't get any information about what SID you intend to fly.
So YES the procedure gradient is of HIGH importance to your all engines operating takeoff.
Here is the example:
Moderator
this is of HIGH relevance to the all engines operating takeoff.
You are mixing two concerns. First, the takeoff bit and then the subsequent departure. Both need to be considered and the more critical determines the final departure weight.
unable to met the 15.2% climb requirement for all engines operating.
Again, not relevant to the actual takeoff calculations but may become the critical path for final weight figures. The two must be treated separately and then the more restrictive becomes the critical figure. Not philosophically different to the case where, say, the enroute cruise OEI weight limit to clear the mountain range restricts departure weight below the RTOW.
You are mixing two concerns. First, the takeoff bit and then the subsequent departure. Both need to be considered and the more critical determines the final departure weight.
unable to met the 15.2% climb requirement for all engines operating.
Again, not relevant to the actual takeoff calculations but may become the critical path for final weight figures. The two must be treated separately and then the more restrictive becomes the critical figure. Not philosophically different to the case where, say, the enroute cruise OEI weight limit to clear the mountain range restricts departure weight below the RTOW.
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An old pirate theory goes that an obstacle that you can see is not an obstacle.
Of course that is nonsense, but in the case of a L/G down departure, I think you will be able to assess very clearly if you have a problem or not.
But, both the L/G down and an engine failure on top of that? Wow, that's not your day! there is a procedure for that, though:
FINGERS………CROSS
Personally I don't know what I would do. In my airplane, avoid obstacles visually, if in IMC go for the EOSID and pray, or "fly the black", or try to return overhead the airfield, although such turn would kill most of my climb ability…
FINGERS……..CHECK CROSSED
Of course that is nonsense, but in the case of a L/G down departure, I think you will be able to assess very clearly if you have a problem or not.
But, both the L/G down and an engine failure on top of that? Wow, that's not your day! there is a procedure for that, though:
FINGERS………CROSS
Personally I don't know what I would do. In my airplane, avoid obstacles visually, if in IMC go for the EOSID and pray, or "fly the black", or try to return overhead the airfield, although such turn would kill most of my climb ability…
FINGERS……..CHECK CROSSED
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You are mixing two concerns. First, the takeoff bit and then the subsequent departure. Both need to be considered and the more critical determines the final departure weight.
I am talking about the ACTUAL takeoff. In 99.999% of the cases you are NOT going to be experiencing an engine failure (for which your takeoff performance calculations have been made).
So your takeoff will not be a "takeoff bit"... it will ONLY be the departure, as long as your engine doesn't fail.
The "takeoff bit" will only be relevant if your engine fails. It's a purely hypothetic "what-if" calculation. The ACTUAL departure is very real - every time.
P.s.
...it's funny that you say I am mixing things up, when I started out in the first post to say that
It's common that certification requirements are being mixed up with procedural requirements.
Facts are:
- You can safely takeoff with gear extended (except in cases like Cologne NOR8F, with an extreme procedural gradient requirement).
- You do not need to apply MEL for flying with gear extended, if retraction is operable.
- It will have no impact on your takeoff performance calculations and doesn't need to be accounted for (as you can retract the gear if necessary)
- If an engine fails, you retract the gear as usual.
End of story.
Last edited by cosmo kramer; 23rd Jun 2015 at 00:30.
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I am not a fan of that concept. I prefer the topic discussed to the end, where everyone agrees.
Why should I operate according to MEL for gear U/S, just because I delay retraction?
Rhetorical question:
In the example of NOR8F, I have to delay flap retraction to 4000 feet as well, as I can't afford to accelerate if I want to comply with the altitude restriction at 4.8 NM KBO VOR. Engine failure procedure will have me retracting them at 1900 feet (1500 feet AGL). Should I in this case check the MEL for restrictions for flying with flaps U/S?
Obviously not. Why should it be different for the landing gear?
Wrong, the pilot operating the aircraft needs to be flexible, and make sure to comply with the challenges of each individual departure. For that, the performance manual is a tool to support the pilot in making good decisions.
Why should I operate according to MEL for gear U/S, just because I delay retraction?
Rhetorical question:
In the example of NOR8F, I have to delay flap retraction to 4000 feet as well, as I can't afford to accelerate if I want to comply with the altitude restriction at 4.8 NM KBO VOR. Engine failure procedure will have me retracting them at 1900 feet (1500 feet AGL). Should I in this case check the MEL for restrictions for flying with flaps U/S?
Obviously not. Why should it be different for the landing gear?
The AFM defines what a normal takeoff might be, not the pilot on the day.
Moderator
OK, let's continue with the discussion ..
Why should I operate according to MEL for gear U/S, just because I delay retraction?
What does your AFM say in respect of selection of gear during the takeoff ? Commonly something along the lines of "retract gear three seconds after liftoff .. ?"
If the pilot wishes to operate in a manner significantly different to that specified in the AFM, which may/will compromise the certification basis, then one needs to consider what answers the pilot might have to questions at the Enquiry after the mishap .. regardless of whether the point in question has any relevance to the mishap.
No different to, say, using a non-AFM flap setting for takeoff .. eg nil flap on light twins .. which I routinely did in the past. For the twins I routinely flew, I had done sufficient climb testing to provide me with the basis for the variation and, more importantly, the basis for an argument in court.
In essence .. in the absence of an abnormal/emergency, either you do
(a) sufficient certification work to establish compliance and a defence at law or
(b) follow the AFM or
(c) use the MEL as your get-out-of-jail-free card
Just to say that you will do what you want to do today because you are the pilot is a rather reckless approach to risk management, I suggest.
I have to delay flap retraction to 4000 feet ... Engine failure procedure will have me retracting them at 1900 feet (1500 feet AGL). Should I in this case check the MEL for restrictions for flying with flaps U/S?
A facile argument. The takeoff will (or should) have been predicated on
(a) the AEO requirements, AND
(b) the OEI escape as appropriate.
A pilot (generally not the reputable airlines) without benefit of a rigorous ops engineering department takeoff procedure in support who departs without an AEO to OEI transition plan to cover all eventualities eventually may not have a good day .... He/she certainly won't have an easy time of a subsequent Enquiry.
the performance manual is a tool to support the pilot in making good decisions.
No. The performance data is to provide the pilot with information to permit compliance with the rulebook. The pilot should be making sensible decisions within the parameters of those requirements for other than emergency situations beyond the normally expected planning regime.
Alternatively, one could pose the question .. how does the pilot, in the situation you posit, make good decisions whilst winging it on the fly ? I put to you that a good decision requires both a successful outcome (in respect of the decision process) and a defensible logic .. the latter including compliance with the Design and Operating Standards where operations, essentially, are normal.
Why should I operate according to MEL for gear U/S, just because I delay retraction?
What does your AFM say in respect of selection of gear during the takeoff ? Commonly something along the lines of "retract gear three seconds after liftoff .. ?"
If the pilot wishes to operate in a manner significantly different to that specified in the AFM, which may/will compromise the certification basis, then one needs to consider what answers the pilot might have to questions at the Enquiry after the mishap .. regardless of whether the point in question has any relevance to the mishap.
No different to, say, using a non-AFM flap setting for takeoff .. eg nil flap on light twins .. which I routinely did in the past. For the twins I routinely flew, I had done sufficient climb testing to provide me with the basis for the variation and, more importantly, the basis for an argument in court.
In essence .. in the absence of an abnormal/emergency, either you do
(a) sufficient certification work to establish compliance and a defence at law or
(b) follow the AFM or
(c) use the MEL as your get-out-of-jail-free card
Just to say that you will do what you want to do today because you are the pilot is a rather reckless approach to risk management, I suggest.
I have to delay flap retraction to 4000 feet ... Engine failure procedure will have me retracting them at 1900 feet (1500 feet AGL). Should I in this case check the MEL for restrictions for flying with flaps U/S?
A facile argument. The takeoff will (or should) have been predicated on
(a) the AEO requirements, AND
(b) the OEI escape as appropriate.
A pilot (generally not the reputable airlines) without benefit of a rigorous ops engineering department takeoff procedure in support who departs without an AEO to OEI transition plan to cover all eventualities eventually may not have a good day .... He/she certainly won't have an easy time of a subsequent Enquiry.
the performance manual is a tool to support the pilot in making good decisions.
No. The performance data is to provide the pilot with information to permit compliance with the rulebook. The pilot should be making sensible decisions within the parameters of those requirements for other than emergency situations beyond the normally expected planning regime.
Alternatively, one could pose the question .. how does the pilot, in the situation you posit, make good decisions whilst winging it on the fly ? I put to you that a good decision requires both a successful outcome (in respect of the decision process) and a defensible logic .. the latter including compliance with the Design and Operating Standards where operations, essentially, are normal.
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What does your AFM say in respect of selection of gear during the takeoff ? Commonly something along the lines of "retract gear three seconds after liftoff .. ?"
"Retract the landing gear AFTER a positive rate of climb is indicated on the altimeter."
It doesn't say how long after, just that you obviously shouldn't do it BEFORE positive rate of climb.
If the pilot wishes to operate in a manner significantly different to that specified in the AFM, which may/will compromise the certification basis
I have to delay flap retraction to 4000 feet ... Engine failure procedure will have me retracting them at 1900 feet (1500 feet AGL). Should I in this case check the MEL for restrictions for flying with flaps U/S?
A facile argument. The takeoff will (or should) have been predicated on
(a) the AEO requirements, AND
(b) the OEI escape as appropriate.
A facile argument. The takeoff will (or should) have been predicated on
(a) the AEO requirements, AND
(b) the OEI escape as appropriate.
So in the flaps example:
(a) Is ok to check that I can takeoff with flaps extended and keeping them extended to 4000 feet in AEO, AND
(b) in case of OEI, I have checked that the flaps need to be retracted earlier (at 1900 feet).
In the case of the gear extended I can do exactly the same checks!:
(a) AEO/gear down, I met any procedural gradients required in my SID (usually 3.3 percent), AND
(b) in case of OEI, I have checked that the gear needs to be retracted earlier (after liftoff and positive rate of climb or when an engine fails, whichever is later).
Alternatively, one could pose the question .. how does the pilot, in the situation you posit, make good decisions whilst winging it on the fly ?
...the basis for an argument in court...
...your get-out-of-jail-free card...
...He/she certainly won't have an easy time of a subsequent Enquiry....
...your get-out-of-jail-free card...
...He/she certainly won't have an easy time of a subsequent Enquiry....
Most incident investigations are there to help the pilots! And to understand and learn from what happened.
Yet I hear this kind of argument often. I NEVER worry about having to go to jail (let alone court), when doing my work as I never do acts of gross negligence.
Maybe something to think of, so we can stop this kind of argumentation.
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Boeing 737 FCTM:
Touch and Go Landing - General
Accomplish the pattern and approach procedures as illustrated. The landing gear may remain extended throughout the maneuver for brake cooling, but be prepared to retract the landing gear if an actual engine failure occurs during go-around.
Touch and Go Landing - General
Accomplish the pattern and approach procedures as illustrated. The landing gear may remain extended throughout the maneuver for brake cooling, but be prepared to retract the landing gear if an actual engine failure occurs during go-around.
Do you think the aircraft "knows" the difference between if it's doing a takeoff or doing patterns?
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Performance limitations and operating procedures
If I may be permitted to add a few observations to the discussion:
A distinction needs to be made between limitations and procedures.
“The aircraft is (obviously) certified to takeoff, fly and land with gear down.”
That is a somewhat simplistic statement. The aircraft is certified for operation within the limitations stated in the Airplane Flight Manual (AFM). The AFM states that the weight that achieves the minimum climb gradients for altitude and temperature (WAT limit), and allows takeoff within the available lengths of runway, is an operating limitation.
In addition, there are usually operating rules, for example FAR parts 91 and 121. FAR 121 adds the requirement that the takeoff weight must permit a net flightpath that clears obstacles by the required margins.
Although most performance limitations are based on a scenario of engine failure, it is not correct to say that they are totally divorced from the performance in normal operation with all engines operating. That is perhaps somewhat beyond the scope of this forum, to understand it you have to go back to the origin in the Final Report of the SCOP that JT mentioned. Let’s just say that the certification basis assumes that the airplane will be operated by qualified pilots in accordance with the recommended procedures.
Note that all performance limitations are stated as a maximum allowable weight for the prevailing conditions. Exceeding any of those limitations is an offence against the law and may result in sanctions, irrespective of whether that exceedance is a factor in an investigation. However, any accident report that I know of, usually has a statement in one of the first sections to the effect that “the weight and loading were within limits”.
Then there are operating procedures. Operating procedures for performance are stated in the AFM in the form of ‘guidance material’, to enable the flight crew to achieve the performance assumed in the calculation of weight limitations. Deviating from those procedures is not a punishable offence, but may result in an invitation for a “tea and biscuits” with the chief pilot. If the deviation is a factor in an incident or accident, the pilot will be asked to explain why he considered it safe to deviate from the Standard Operating Procedure (SOP). If the investigation finds that explanation unsatisfactory, sanctions may follow.
Regarding flap retraction after takeoff from Cologne, my understanding is that such on operating restriction is usually complied with by maintaining a certain rate-of-climb. The acceleration remaining while maintaining that rate of climb will determine when you reach flap retraction speed. At that speed you can retract the flaps.
P.S.
Another way to put it: by delaying gear retraction, you’re reducing the performance margin that you may need in a contingency. In other words, you’re making the takeoff less safe than it could have been, unless you can show a safety benefit for delaying gear retraction.
A distinction needs to be made between limitations and procedures.
“The aircraft is (obviously) certified to takeoff, fly and land with gear down.”
That is a somewhat simplistic statement. The aircraft is certified for operation within the limitations stated in the Airplane Flight Manual (AFM). The AFM states that the weight that achieves the minimum climb gradients for altitude and temperature (WAT limit), and allows takeoff within the available lengths of runway, is an operating limitation.
In addition, there are usually operating rules, for example FAR parts 91 and 121. FAR 121 adds the requirement that the takeoff weight must permit a net flightpath that clears obstacles by the required margins.
Although most performance limitations are based on a scenario of engine failure, it is not correct to say that they are totally divorced from the performance in normal operation with all engines operating. That is perhaps somewhat beyond the scope of this forum, to understand it you have to go back to the origin in the Final Report of the SCOP that JT mentioned. Let’s just say that the certification basis assumes that the airplane will be operated by qualified pilots in accordance with the recommended procedures.
Note that all performance limitations are stated as a maximum allowable weight for the prevailing conditions. Exceeding any of those limitations is an offence against the law and may result in sanctions, irrespective of whether that exceedance is a factor in an investigation. However, any accident report that I know of, usually has a statement in one of the first sections to the effect that “the weight and loading were within limits”.
Then there are operating procedures. Operating procedures for performance are stated in the AFM in the form of ‘guidance material’, to enable the flight crew to achieve the performance assumed in the calculation of weight limitations. Deviating from those procedures is not a punishable offence, but may result in an invitation for a “tea and biscuits” with the chief pilot. If the deviation is a factor in an incident or accident, the pilot will be asked to explain why he considered it safe to deviate from the Standard Operating Procedure (SOP). If the investigation finds that explanation unsatisfactory, sanctions may follow.
Regarding flap retraction after takeoff from Cologne, my understanding is that such on operating restriction is usually complied with by maintaining a certain rate-of-climb. The acceleration remaining while maintaining that rate of climb will determine when you reach flap retraction speed. At that speed you can retract the flaps.
P.S.
Another way to put it: by delaying gear retraction, you’re reducing the performance margin that you may need in a contingency. In other words, you’re making the takeoff less safe than it could have been, unless you can show a safety benefit for delaying gear retraction.
Last edited by Gysbreght; 25th Jun 2015 at 18:49. Reason: adding a P.S.
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Another way to put it: by delaying gear retraction, you’re reducing the performance margin that you may need in a contingency. In other words, you’re making the takeoff less safe than it could have been, unless you can show a safety benefit for delaying gear retraction.
Since NOT retracting gear has already been accounted for, the requirements for all eventualities have already been covered.
What you are saying is basically this:
If an engine fails, AND a mistake is made (like not following the engine failure contingency procedure), then the difference between having had the gear extended might get you into trouble.
That is true, but we have loads of such procedures that reduces margin. Some obvious are:
- Reduced takeoff thrust.
- Fuel tankering
There are indirect reductions in margin as well:
- Flying with a full passenger load (empty aircraft performs better).
This is such a procedure too:
- Flying with the gear extended is a commercial consideration (to reduce turnaround time).
An example to make this more palpable, 3 legs:
- You fly to Egypt with fuel tankering.
- You land at your destination with max landing weight in 45 deg C.
- You have 45 mins turnaround, and the brakes are allowed to be cooled sufficient to perform another takeoff.
- There after you fly a short 20 min to another Egyptian airport and land at max landing weight again in 45 deg C.
a) If you retract your gear during the short leg, accumulation of the heat from first and second landing will require a long brake cooling time, before you can leave again.
b) You fly with gear extended and you can make a quick turnaround between leg 2 and leg 3.
For leg 2 (the flight with gear extended), all requirements are being adhered to. All eventualities have been covered.
- The brakes were sufficient cool to reject a takeoff.
- For AEO with gear extended, I can safely follow applicable SID and adhere to the required climb gradient.
- For OEI, I can safely retract the gear and follow my contingency procedure (no need to apply MEL restrictions).
- In either case, my brakes are cool enough to allow for an immediate landing.
- If the gear is extended or not, only has a bearing on how long I have to wait before I can perform leg 3.
The above b) is a recommended procedure in my company...
Just to say that you will do what you want to do today because you are the pilot is a rather reckless approach to risk management, I suggest.
I am not doing anything illegal, I am not going to court or jail, and I won't be having tea and biscuits with anyone. Most likely I will be drinking my black coffee with my F/O on leg 3 back after a short turnaround.
P.s.
Regarding Cologne, you have to fly at V2 until reaching 4000 feet. Hence, there is no acceleration.
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What you are saying is basically this:
If an engine fails, AND a mistake is made (like not following the engine failure contingency procedure), then the difference between having had the gear extended might get you into trouble.
If an engine fails, AND a mistake is made (like not following the engine failure contingency procedure), then the difference between having had the gear extended might get you into trouble.
You're just being stubborn.
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or the famous ditching of an A320 in the Hudson river. In the latter case, when the plane hit a flock of geese, a couple of 100 ft might have made the difference between being able to reach a runway or having to ditch.
A reduction of takeoff thrust was obviously a reduction of margin.
Did anyone blame them?
Did anyone go to jail?
Of course not, since it's part of an acceptable risk. Anything that reduces our margin is most of the time a commercial compromise.
You're just being stubborn.
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Given that all the performance data published in the AFM/AOM is defined by configuration, thrust and speed I'm not sure, unless like JT you happen to have gathered certification data, how a pilot can account for a deviation from the prescribed configuration, thrust and speed without a great deal of guess work.
As for post v1 failures, I'm pretty sure the company will have something to say about how to handle them. e.g. appropriate SID turn backs or visual terrain clearance.
and someone mentioned earlier that TO software doesn't account for AEO SID requirements. Well it can and does in our case where we can select a specific SID with sometimes limiting gradient requirements. It will then add this limiting AEO case to the list of limiting weights. Lowest one wins as usual.
As for post v1 failures, I'm pretty sure the company will have something to say about how to handle them. e.g. appropriate SID turn backs or visual terrain clearance.
and someone mentioned earlier that TO software doesn't account for AEO SID requirements. Well it can and does in our case where we can select a specific SID with sometimes limiting gradient requirements. It will then add this limiting AEO case to the list of limiting weights. Lowest one wins as usual.
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cosmo cramer:
Just to set the record straight, from the NTSB Accident report:
With 99% likelihood, US1549 departed with derate and assumed temperature thrust reduction.
According to the weight and balance manifest provided by US Airways, the airplane departed LGA with a takeoff weight of 151,510 pounds, which was below the maximum limitation takeoff weight of 151,600 pounds.