Overweight Landing and Field Length
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A few issues which I don't think have been considered jump up here in my mind;
1. Initial problem is described as Depressurisation. Was it a failure to pressurise i.e. climb stopped at or below FL100 or even FL125 and then back to FL100 due to the cabin climbing? or Was the aircraft at FL150+ and the cabin depressurised, oxygen masks deployed? What was the rate of depressurisation?
Basically - can thre be people back there who could have medical issues because of the depressurisation problem?
That would make it a good idea to return sooner rather than later.
2. It appears that it is going to take 2 hours at low level to burn off the fuel to acheive a MLW arrival. Is there no suitable airport within less than 2 hours that the aircraft can land at as soon as it gets there?
3. Can the aircraft comply with the missed approach and balked landing climb gradients at the expected mass?
4. It is night. How long until daytime? What is the weather going to do in the next few hours?
These are issues that I would expect to be part of the decision process.
As for the runway lengths?
If the aircraft returns quickly then the full safety factor is not available. However, the aircraft will not be at TOW when it lands i.e. even an aircraft that takes off at MTOW, catches fire 10Kt above V1 and does a tight visual circuit to land will not land at the take-off weight.
The aircraft completed a safe take-off on the runway. Thus in theory, starting at the piano keys, it could accelerate to V1 and for another 2 seconds and then stop with one engine out without ending up in the mud.
What is V1 in relation to your touchdown speed? and where is it roughly on the runway? I would expect that V1 did not occur at or before the aiming point?
These are some of the factors that have to be considdered.
Having said all that, if the climb was stopped at 5000ft becuase the cabin was climbing with the aircraft and there is no other reason to return plus the fact that we are at an isolated aerodrome, I would be more in favour of waiting for the weight to reduce because anything else is rushing and putting money before safety.
To burn off the fuel, I would prefer flying long straight legs with only drag items that do not cause a lot of noise / bumping. This keeps the pax happier. It may take time - but they expected to be on the flight for a lot more than the 2 hours it is going to take to burn off the fuel low level(if that is not the case then how were you going to land at the destination?). Subject to SOP, they could receive an in-flight service and time taken to liase with pax and company regarding later flights.
Think of it like this -
Dear Pax,
I realise that you are not feeling 100% secure with the situation but there is no immediate danger. Would you prefer to;
1. Return for an overweight landing with possible dangerous over-run then (if ) we make it to the terminal, q at a desk for 1 hour to re-book and then sit on the uncomfortable terminal seats for 3 hours; or
2. Sit here strapped in for 1 hour with the noise and turbulence of the gear and spoilers extended before making a normal landing and q at a desk for 1 hour to re-book and then sit on the uncomfortable terminal seats for 2 hours; or
3. Sit here for 2 hours, have your in-flight service, watch the movie, let us have time to book your replacement flight and when we safely arrive back at the terminal, have 1 hour to collect your bags, check-in and proceed to the gate?
In each case the delay for the pax is the same but 1 has the added posibiity of never getting to the destination!!
In the end it is a Command decision. These are just s few points that I feel must be weighed up. There are no doubt plenty more and the longer one takes to review the options fully, the lower the landing weight!!!!!!!
1. Initial problem is described as Depressurisation. Was it a failure to pressurise i.e. climb stopped at or below FL100 or even FL125 and then back to FL100 due to the cabin climbing? or Was the aircraft at FL150+ and the cabin depressurised, oxygen masks deployed? What was the rate of depressurisation?
Basically - can thre be people back there who could have medical issues because of the depressurisation problem?
That would make it a good idea to return sooner rather than later.
2. It appears that it is going to take 2 hours at low level to burn off the fuel to acheive a MLW arrival. Is there no suitable airport within less than 2 hours that the aircraft can land at as soon as it gets there?
3. Can the aircraft comply with the missed approach and balked landing climb gradients at the expected mass?
4. It is night. How long until daytime? What is the weather going to do in the next few hours?
These are issues that I would expect to be part of the decision process.
As for the runway lengths?
If the aircraft returns quickly then the full safety factor is not available. However, the aircraft will not be at TOW when it lands i.e. even an aircraft that takes off at MTOW, catches fire 10Kt above V1 and does a tight visual circuit to land will not land at the take-off weight.
The aircraft completed a safe take-off on the runway. Thus in theory, starting at the piano keys, it could accelerate to V1 and for another 2 seconds and then stop with one engine out without ending up in the mud.
What is V1 in relation to your touchdown speed? and where is it roughly on the runway? I would expect that V1 did not occur at or before the aiming point?
These are some of the factors that have to be considdered.
Having said all that, if the climb was stopped at 5000ft becuase the cabin was climbing with the aircraft and there is no other reason to return plus the fact that we are at an isolated aerodrome, I would be more in favour of waiting for the weight to reduce because anything else is rushing and putting money before safety.
To burn off the fuel, I would prefer flying long straight legs with only drag items that do not cause a lot of noise / bumping. This keeps the pax happier. It may take time - but they expected to be on the flight for a lot more than the 2 hours it is going to take to burn off the fuel low level(if that is not the case then how were you going to land at the destination?). Subject to SOP, they could receive an in-flight service and time taken to liase with pax and company regarding later flights.
Think of it like this -
Dear Pax,
I realise that you are not feeling 100% secure with the situation but there is no immediate danger. Would you prefer to;
1. Return for an overweight landing with possible dangerous over-run then (if ) we make it to the terminal, q at a desk for 1 hour to re-book and then sit on the uncomfortable terminal seats for 3 hours; or
2. Sit here strapped in for 1 hour with the noise and turbulence of the gear and spoilers extended before making a normal landing and q at a desk for 1 hour to re-book and then sit on the uncomfortable terminal seats for 2 hours; or
3. Sit here for 2 hours, have your in-flight service, watch the movie, let us have time to book your replacement flight and when we safely arrive back at the terminal, have 1 hour to collect your bags, check-in and proceed to the gate?
In each case the delay for the pax is the same but 1 has the added posibiity of never getting to the destination!!
In the end it is a Command decision. These are just s few points that I feel must be weighed up. There are no doubt plenty more and the longer one takes to review the options fully, the lower the landing weight!!!!!!!
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The primary Federal Aviation Administration (FAA )
regulations involved in landing overweight and fuel
jettison are:
■ Federal Aviation Regulation (FAR ) 25.1519 —
Requires the maximum landing weight to be an
operating limitation.
■ FAR 91.9 — Requires compliance with
operating limitations.
■ FAR 121.557 and FAR 121.559 — Allow the
pilot in command to deviate from prescribed
procedures as required in an emergency
situation in the interest of safety.
In June 1972,the FAA issued Air Carrier Operations Bulletin
No. 72-11 giving three examples of situations
the FAA considered typical of those under
which pilots may be expected to use their
emergency authority in electing to land
overweight:
■ Any malfunction that would render the
airplane unairworthy.
■ Any condition or combination, thereof,
mechanical or otherwise, in which an
expeditious landing would reduce the
exposure to the potential of additional
problems which would result in a
derogation or compromise of safety.
■ Serious illness of crew or passengers which
would require immediate medical attention.
http://www.boeing.com/commercial/aer...icle_03_1.html
In this scenario at best you may argue that avionic cooling may be compromised by prolonged flight but that would be tenuous at best.
You need to look for the least risk and that is not landing overweight in this case.
regulations involved in landing overweight and fuel
jettison are:
■ Federal Aviation Regulation (FAR ) 25.1519 —
Requires the maximum landing weight to be an
operating limitation.
■ FAR 91.9 — Requires compliance with
operating limitations.
■ FAR 121.557 and FAR 121.559 — Allow the
pilot in command to deviate from prescribed
procedures as required in an emergency
situation in the interest of safety.
In June 1972,the FAA issued Air Carrier Operations Bulletin
No. 72-11 giving three examples of situations
the FAA considered typical of those under
which pilots may be expected to use their
emergency authority in electing to land
overweight:
■ Any malfunction that would render the
airplane unairworthy.
■ Any condition or combination, thereof,
mechanical or otherwise, in which an
expeditious landing would reduce the
exposure to the potential of additional
problems which would result in a
derogation or compromise of safety.
■ Serious illness of crew or passengers which
would require immediate medical attention.
http://www.boeing.com/commercial/aer...icle_03_1.html
In this scenario at best you may argue that avionic cooling may be compromised by prolonged flight but that would be tenuous at best.
You need to look for the least risk and that is not landing overweight in this case.
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To Open Des, RudderRudderRat, Cough, SafetyPee, John Tullamarine and FE Hoppy
-------------------------------------------------------------------------------------------------
Thankyou all for your answers and information.
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To Intruder
-------------
Thankyou for your response. Regarding the extra details you want to know:
- Departure airport is the only option.
- The factored landing distance equals the runway length at Max Landing Weight.
- Why 1.67 % is used? It's a dispatch safety figure for landing and thats what the discussion is all about that, "Can it be used once the A/C is airborne?"
- Unfactored landing distance of 5700 feet which I mentioned in the example is with operational reversers and autobrakes.
So with this extra info do you still hold your answer of Landing and not waiting? Thanx.
---------------------
To CityFan
---------------------
Thankyou for your response. Regarding some extra details regarding the example:
- Getting down to the factored (1.67) landing distance required burning 7000 Kg fuel i.e. to avoid legal implications in addition to safety.
- Brakes, Reversers, Spoilers, Anti-skid, etc all operational. And considering all of these, the factored distance came out to be 5700 feet.
- Full manual braking in high energy stops have caused tire deflations also. So even if you stop safely within the runway filed length avaialble but you are unable to taxi and block the runway and by any chance disemabark your passengers on the runway, then what do you think think about the legal implications?
So with this extra info do you still hold your answer of Landing and not waiting? Thanx.
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To QualityTimes
---------------------
Thankyou for your response. Just for clarity I mention again:
- After consulting the QRH the unfactored distance is 5700 feet. Performace wise field length is not enough if we apply 1.67 safety factor. However if we dont use 67% safety factor then we are within our field length. So is it OK not to use 67% safety factor once airborne? Will this be legally covered?
- This example is not a Mayday or Pan situation. Soon after takeoff there is complete depressurization and the A/C is under control below 10,000 feet. Everything else is normal.
So with this extra info do you still hold your answer of Landing and not waiting? Thanx.
---------------------
To DFC
---------------------
Thankyou for your response. Regarding some extra details about the example which you need to know:
- Soon after takeoff there is complete depressurization and the A/C is under control below 10,000 feet. Everything else is normal. However your
answer has covered this situation and you said you would rather wait to land.
To Open Des, RudderRudderRat, Cough, SafetyPee, John Tullamarine and FE Hoppy
-------------------------------------------------------------------------------------------------
Thankyou all for your answers and information.
-------------
To Intruder
-------------
Thankyou for your response. Regarding the extra details you want to know:
- Departure airport is the only option.
- The factored landing distance equals the runway length at Max Landing Weight.
- Why 1.67 % is used? It's a dispatch safety figure for landing and thats what the discussion is all about that, "Can it be used once the A/C is airborne?"
- Unfactored landing distance of 5700 feet which I mentioned in the example is with operational reversers and autobrakes.
So with this extra info do you still hold your answer of Landing and not waiting? Thanx.
---------------------
To CityFan
---------------------
Thankyou for your response. Regarding some extra details regarding the example:
- Getting down to the factored (1.67) landing distance required burning 7000 Kg fuel i.e. to avoid legal implications in addition to safety.
- Brakes, Reversers, Spoilers, Anti-skid, etc all operational. And considering all of these, the factored distance came out to be 5700 feet.
- Full manual braking in high energy stops have caused tire deflations also. So even if you stop safely within the runway filed length avaialble but you are unable to taxi and block the runway and by any chance disemabark your passengers on the runway, then what do you think think about the legal implications?
So with this extra info do you still hold your answer of Landing and not waiting? Thanx.
---------------------
To QualityTimes
---------------------
Thankyou for your response. Just for clarity I mention again:
- After consulting the QRH the unfactored distance is 5700 feet. Performace wise field length is not enough if we apply 1.67 safety factor. However if we dont use 67% safety factor then we are within our field length. So is it OK not to use 67% safety factor once airborne? Will this be legally covered?
- This example is not a Mayday or Pan situation. Soon after takeoff there is complete depressurization and the A/C is under control below 10,000 feet. Everything else is normal.
So with this extra info do you still hold your answer of Landing and not waiting? Thanx.
---------------------
To DFC
---------------------
Thankyou for your response. Regarding some extra details about the example which you need to know:
- Soon after takeoff there is complete depressurization and the A/C is under control below 10,000 feet. Everything else is normal. However your
answer has covered this situation and you said you would rather wait to land.
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So far if I try to summarize the discussion, I think the main issue comes out to be using the 1.67 safety factor for landing i.e. incase of a landback at departure airport above MLW with No Emergency condition requiring to Land ASAP.
The situation is that if you apply the safety factor then your factored distance is more than your field length and if you dont apply the safety factor then your unfactored distance is well within the avaialble field length.
Now the issue is whether one should apply the safety factor after airborne or not? If yes then how much, 1.67 or some other figure?
So far we havent seen anything in Black and White from regulatory authoritues regarding application of 1.67 safety factor after airborne, which seems to be the bone of contention.
However one group thinks that it should be applied and have justified their answers with text of various safety documents which is mentioned above in this thread. This group is conservative in reference to safety and legality.
Other group thinks since there is no Black and White evidence that you have to apply the 1.67 safety factor after airborne, you should save money and land if your unfactored distance is less than the field length.
However at this point of discussion I would like to know, if for some odd reason those who want to land go into an over-run or land on the runway with a flat tyre, then would they be legally covered?
Now I am more interested in finding some definite ruling on using the 1.67 safety factor once airborne, and there is no emergency to land ASAP.
Thanks once again to all of you who are contributing to this issue.
The situation is that if you apply the safety factor then your factored distance is more than your field length and if you dont apply the safety factor then your unfactored distance is well within the avaialble field length.
Now the issue is whether one should apply the safety factor after airborne or not? If yes then how much, 1.67 or some other figure?
So far we havent seen anything in Black and White from regulatory authoritues regarding application of 1.67 safety factor after airborne, which seems to be the bone of contention.
However one group thinks that it should be applied and have justified their answers with text of various safety documents which is mentioned above in this thread. This group is conservative in reference to safety and legality.
Other group thinks since there is no Black and White evidence that you have to apply the 1.67 safety factor after airborne, you should save money and land if your unfactored distance is less than the field length.
However at this point of discussion I would like to know, if for some odd reason those who want to land go into an over-run or land on the runway with a flat tyre, then would they be legally covered?
Now I am more interested in finding some definite ruling on using the 1.67 safety factor once airborne, and there is no emergency to land ASAP.
Thanks once again to all of you who are contributing to this issue.
Last edited by Haroon; 14th Nov 2009 at 05:18.
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Haroon
As has been stated before the 1.67/1.92 factors apply to the planning stage, once you are airborne not so.
IMO you don't have to have an emergency situation to justify landing overweight. Even FO Hoppy undermines his own argument by highlighting the requirement.....
The Boeing FCTM does not make a big deal out of overweight landings.The first sentence stating........'Overweight landings may be safely accomplished by using normal landing procedures and techniques.'
I note also that the B737 Management reference Guide (Author PBoone)
includes the following guidance on overweight landings.
Recommended
Not making light of the scenario,it's one of those that will split opinions/actions. I have said I would land but on the day I might not do so immediately.Some operations manuals will give clear guidance where others will leave it to the Captain on the day.
Call operations if you can so they get the bo**ocking if it goes pear shaped!
Either way cover your ass and do what you believe to be safe and legal.
As has been stated before the 1.67/1.92 factors apply to the planning stage, once you are airborne not so.
IMO you don't have to have an emergency situation to justify landing overweight. Even FO Hoppy undermines his own argument by highlighting the requirement.....
- Any malfunction that would render the aircraft unairworthy.
The Boeing FCTM does not make a big deal out of overweight landings.The first sentence stating........'Overweight landings may be safely accomplished by using normal landing procedures and techniques.'
I note also that the B737 Management reference Guide (Author PBoone)
includes the following guidance on overweight landings.
Recommended
- A malfunction that seriously affects the airworthiness of the a/c
- A condition whereby a late landing would increase the exposure to a degrading level of safety
- One engine inop
- A serious illness requiring ammediate medical attention
- A malfunction not directly affecting the airworthiness of the a/c
- An unplanned diversion
Not making light of the scenario,it's one of those that will split opinions/actions. I have said I would land but on the day I might not do so immediately.Some operations manuals will give clear guidance where others will leave it to the Captain on the day.
Call operations if you can so they get the bo**ocking if it goes pear shaped!
Either way cover your ass and do what you believe to be safe and legal.
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QT.
If i can release under the MEL for unpressurised flight then i am most definitely NOT un-airworthy.
Please note that the advise comes from the FAA via Boeing, it's not something i made up in the pub.
If i can release under the MEL for unpressurised flight then i am most definitely NOT un-airworthy.
Please note that the advise comes from the FAA via Boeing, it's not something i made up in the pub.
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FE Hoppy
You can release a four engined a/c for a 3 engine ferry under the MEL too but I wouldn't call the a/c airworthy in the normal sense.
I know you didn't make it up in the pub but there is plenty of official 'advice' in the aviation world that is as about as clear as mud.
You can release a four engined a/c for a 3 engine ferry under the MEL too but I wouldn't call the a/c airworthy in the normal sense.
I know you didn't make it up in the pub but there is plenty of official 'advice' in the aviation world that is as about as clear as mud.
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If i can release under the MEL for unpressurised flight then i am most definitely NOT un-airworthy.
If a crew walked out to a A340 with an engine u/s you would try to convince the skipper it was airworthy ?
Best of luck.
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you are completely missing the point mate.
Of course you cannot accept an engine out before dispatch i didn't imply you could. You have tried to tie two unrelated points together.
There is a thread on here about flying across the pond with an engine out. The flight crew were completely justified as proved by the fact they were not prosecuted on either side of the atlantic for their judgment.
Of course I'm aware of when the MEL is applicable.
What you are not considering is the legal implications in choosing to land overweight when there is no logical reason to do so.
If the risk of remaining airborne out way the risk of overweight landing then land. If not then reduce weight.
Take a look at all the accidents caused by remaining airborne and reducing weight compared to those caused by landing overweight or on reduced landing distance factors.
Landing overruns are a problem. I can think of at least 3 in the last few years.
There are two arguments going on here.
The first is "landing overweight" the second is accepting a reduced required landing distance. This scenario tests both. I don't believe there is reason to accept a reduced landing distance nor do i believe there is reason to land overweight. I certainly don't believe there is justification in doing both.
Of course you cannot accept an engine out before dispatch i didn't imply you could. You have tried to tie two unrelated points together.
There is a thread on here about flying across the pond with an engine out. The flight crew were completely justified as proved by the fact they were not prosecuted on either side of the atlantic for their judgment.
Of course I'm aware of when the MEL is applicable.
What you are not considering is the legal implications in choosing to land overweight when there is no logical reason to do so.
If the risk of remaining airborne out way the risk of overweight landing then land. If not then reduce weight.
Take a look at all the accidents caused by remaining airborne and reducing weight compared to those caused by landing overweight or on reduced landing distance factors.
Landing overruns are a problem. I can think of at least 3 in the last few years.
There are two arguments going on here.
The first is "landing overweight" the second is accepting a reduced required landing distance. This scenario tests both. I don't believe there is reason to accept a reduced landing distance nor do i believe there is reason to land overweight. I certainly don't believe there is justification in doing both.
Last edited by FE Hoppy; 14th Nov 2009 at 20:54.
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FE Hoppy
I certainly wouldn't have continued all the way to Heathrow( sorry - nearly all the way) but as you have stated my judgement may be flawed.
I agree I would be landing well over the max landing weight but as stated previously the landing distance does not require the 1.67 factoring.
I have in fact considered the legal aspect and have landed overweight myself in both seats in Boeings, real ones.
Yes runway overruns are a problem but they are frequently on very wet runways after a unstable approach or with tailwinds. Risk management is an everyday part of this job and believe it or not other people often get it right.
I disagree with your evaluation.
I certainly wouldn't have continued all the way to Heathrow( sorry - nearly all the way) but as you have stated my judgement may be flawed.
I agree I would be landing well over the max landing weight but as stated previously the landing distance does not require the 1.67 factoring.
I have in fact considered the legal aspect and have landed overweight myself in both seats in Boeings, real ones.
Yes runway overruns are a problem but they are frequently on very wet runways after a unstable approach or with tailwinds. Risk management is an everyday part of this job and believe it or not other people often get it right.
I disagree with your evaluation.
Last edited by Quality Time; 14th Nov 2009 at 20:48.
Re Boeing data usually doesn’t include the 1000ft+ from threshold to touchdown
Can you cite any objective evidence to support this claim ? (#17)
JT at that stage of the thread it was unclear if the unfactored distance quoted included the airborne distance. My statement was poorly worded and it would have been better to ask a direct question.
I have rechecked a 737 ‘Classic’ QRH and the unfactored landing distance tables do include 1000ft airborne distance.
However, I note that the total distance quoted includes 'detent' reverse and thus is not the same basis as for factored landing distances. The details are in the QRH ‘small-print’.
This suggests that the factored distance quoted (9500ft) could be considerably less than would have been calculated with ‘dispatch’ rules using certificated ‘unfactored’ data (no reverse).
A more practical view of the importance of ‘airborne distance’ in determining the actual landing distance, comes from a FDM / FOQA report (SESMA; 12000 landings, 737-400), which shows an average touchdown point around 1000ft beyond the GS location, i.e. about 1900ft beyond the threshold. The report also showed that the median speed at flare height (30ft) was Vref+7. Thus operators should consider adding at least 1000ft to their estimates of actual landing distance.
This addition is also reflected in the FAA advice in SAFO 06012 “The airborne portion of the actual landing distance (distance from runway threshold to touchdown point) should reflect the operator’s specific operations, operational practices, procedures, training, and experience.
Another point is that if the operator’s procedures require full reverse, yet reverse is not credited in the aircraft’s certificated landing data, then landing risk increases due to the probabilities of incorrect selection and operation of reverse. Here (again), operational rules appear to conflict with aircraft certification rules. The SAFO defines both Unfactored Certificated Landing Distance and Actual Landing Distance, the latter better representing flight operations and not theoretical minimums.
In addition, on a dry runway and when required for non-normal landings, crews should always use max manual braking with full reverse. With autobrake, when the deceleration target is reached the contribution from the brakes is reduced, the commanded deceleration is then maintained by a combination of reverse and reduced braking, which is not max deceleration, thus the landing distance is longer.
Can you cite any objective evidence to support this claim ? (#17)
JT at that stage of the thread it was unclear if the unfactored distance quoted included the airborne distance. My statement was poorly worded and it would have been better to ask a direct question.
I have rechecked a 737 ‘Classic’ QRH and the unfactored landing distance tables do include 1000ft airborne distance.
However, I note that the total distance quoted includes 'detent' reverse and thus is not the same basis as for factored landing distances. The details are in the QRH ‘small-print’.
This suggests that the factored distance quoted (9500ft) could be considerably less than would have been calculated with ‘dispatch’ rules using certificated ‘unfactored’ data (no reverse).
A more practical view of the importance of ‘airborne distance’ in determining the actual landing distance, comes from a FDM / FOQA report (SESMA; 12000 landings, 737-400), which shows an average touchdown point around 1000ft beyond the GS location, i.e. about 1900ft beyond the threshold. The report also showed that the median speed at flare height (30ft) was Vref+7. Thus operators should consider adding at least 1000ft to their estimates of actual landing distance.
This addition is also reflected in the FAA advice in SAFO 06012 “The airborne portion of the actual landing distance (distance from runway threshold to touchdown point) should reflect the operator’s specific operations, operational practices, procedures, training, and experience.
Another point is that if the operator’s procedures require full reverse, yet reverse is not credited in the aircraft’s certificated landing data, then landing risk increases due to the probabilities of incorrect selection and operation of reverse. Here (again), operational rules appear to conflict with aircraft certification rules. The SAFO defines both Unfactored Certificated Landing Distance and Actual Landing Distance, the latter better representing flight operations and not theoretical minimums.
In addition, on a dry runway and when required for non-normal landings, crews should always use max manual braking with full reverse. With autobrake, when the deceleration target is reached the contribution from the brakes is reduced, the commanded deceleration is then maintained by a combination of reverse and reduced braking, which is not max deceleration, thus the landing distance is longer.
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To Intruder
-------------
Thankyou for your response. Regarding the extra details you want to know:
- Departure airport is the only option.
- The factored landing distance equals the runway length at Max Landing Weight.
- Why 1.67 % is used? It's a dispatch safety figure for landing and thats what the discussion is all about that, "Can it be used once the A/C is airborne?"
- Unfactored landing distance of 5700 feet which I mentioned in the example is with operational reversers and autobrakes.
So with this extra info do you still hold your answer of Landing and not waiting? Thanx.
To Intruder
-------------
Thankyou for your response. Regarding the extra details you want to know:
- Departure airport is the only option.
- The factored landing distance equals the runway length at Max Landing Weight.
- Why 1.67 % is used? It's a dispatch safety figure for landing and thats what the discussion is all about that, "Can it be used once the A/C is airborne?"
- Unfactored landing distance of 5700 feet which I mentioned in the example is with operational reversers and autobrakes.
So with this extra info do you still hold your answer of Landing and not waiting? Thanx.
I have seen 15% and 40% runway length factors usded in various scenarios. This is the first time I have seen 67% used.
If the 5700' landing distance includes air distance to touchdown point and uses normal (not max) autobrakes, I would still consider landing. I would still check the emergency max landing weight for the airport and compare that to the TO (or current) weight. That will give another indication of relative performance limitations.
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To QualityTimes and FE Hoppy
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I thank both of you for your responses. Just to remove some confusion let me say at this point of discussion that heavy weight landing is not an issue. Main issue at this point of discussion is about the landing distance available and required. i.e.
1) Whether one should apply the safety factor after airborne or not? If yes then how much, 67% or some other figure?
2) If 67% safety margin is required at dispatch to reduce the probability of an overrun then what is it that stops us not to adhere to our flight plan if the situation is not to Land ASAP. Is there anything explicit that stops from using the safety factor once airborne?
Even MEL is also a document to be used on ground for dispatch but its application after airborne can be pretty useful as it can help prevent an A/C to get stuck at a place where there is no maintenace.
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To Intruder
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Thankyou for your response. The unfactored 5700 landing distance includes air distance with Auto Brake Level 3. However after applying 67% safety factor AutoBrake 3 is not sufficient and Max Auto setting needs to be used. Max Auto stops the A/C even after applying the 67% factor but enters us into the Caution Zone in which wheel fuse plugs can melt. Since you normally dont use dispatch safety figures once airborne, this data wont affect your decision. Thanks anyways.
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To Everyone
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Thanks once again for your valuable contributions. I have my Sim check coming up on the 19th at London so I wont be able to spend much time here for the next one week I think. Take care all of you. See you soon.
To QualityTimes and FE Hoppy
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I thank both of you for your responses. Just to remove some confusion let me say at this point of discussion that heavy weight landing is not an issue. Main issue at this point of discussion is about the landing distance available and required. i.e.
1) Whether one should apply the safety factor after airborne or not? If yes then how much, 67% or some other figure?
2) If 67% safety margin is required at dispatch to reduce the probability of an overrun then what is it that stops us not to adhere to our flight plan if the situation is not to Land ASAP. Is there anything explicit that stops from using the safety factor once airborne?
Even MEL is also a document to be used on ground for dispatch but its application after airborne can be pretty useful as it can help prevent an A/C to get stuck at a place where there is no maintenace.
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To Intruder
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Thankyou for your response. The unfactored 5700 landing distance includes air distance with Auto Brake Level 3. However after applying 67% safety factor AutoBrake 3 is not sufficient and Max Auto setting needs to be used. Max Auto stops the A/C even after applying the 67% factor but enters us into the Caution Zone in which wheel fuse plugs can melt. Since you normally dont use dispatch safety figures once airborne, this data wont affect your decision. Thanks anyways.
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To Everyone
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Thanks once again for your valuable contributions. I have my Sim check coming up on the 19th at London so I wont be able to spend much time here for the next one week I think. Take care all of you. See you soon.
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Haroon.
Yes. One should ensure adaquate landing distance. The FAA favour a minimum of 15% but it isn't a regulation, just a recomendation. The NTSB has been rather critical of the FAA in not implementing this as a regulation as they believe it would have prevented at least one over run accident. (ERJ170)
There is much guidance around. The flight safety foundation have a good breifing.
Some manufacturers are now including overspeed data as the unfactored figures require Vref over the threashold but if you have used a wind additive you will most likely be above Vref and therefore require more distance.
If you are landing the aircraft at an un familliar weight or on a sloping or wide or narrow runway you will flare differently than normal.
You will flare differently than the test pilots who did the certification campaing because their job is to bring home the numbers not the passengers.
The amount of additive is currently up to you to decide so if you go off the end it's going to be you explaining.
It's again not exactly clear. What is clear is that a simple in flight re-planning will still require the 1.67 or 1.92 factor according to the current EU-OPS. Not sure about FAA wording. Any Emergency or abnormal may be justification to reduce landing safety factor due to increased risk in flight but then your q1 comes in to play as to how much to reduce by.
1) Whether one should apply the safety factor after airborne or not? If yes then how much, 67% or some other figure?
There is much guidance around. The flight safety foundation have a good breifing.
Some manufacturers are now including overspeed data as the unfactored figures require Vref over the threashold but if you have used a wind additive you will most likely be above Vref and therefore require more distance.
If you are landing the aircraft at an un familliar weight or on a sloping or wide or narrow runway you will flare differently than normal.
You will flare differently than the test pilots who did the certification campaing because their job is to bring home the numbers not the passengers.
The amount of additive is currently up to you to decide so if you go off the end it's going to be you explaining.
2) If 67% safety margin is required at dispatch to reduce the probability of an overrun then what is it that stops us not to adhere to our flight plan if the situation is not to Land ASAP. Is there anything explicit that stops from using the safety factor once airborne?
What is clear is that a simple in flight re-planning will still require the 1.67 or 1.92 factor according to the current EU-OPS.
OPS 1.475
General
General
(a) An operator shall ensure that the mass of the aeroplane:
(1) at the start of the take-off; or, in the event of in-flight replanning
(2) at the point from which the revised operational flight plan applies, is not greater than the mass at which the requirements of the appropriate subpart can be complied with for the flight to be undertaken, allowing for expected reductions in mass as the flight proceeds, and for such fuel jettisoning as is provided for in the particular requirement.
(b) An operator shall ensure that the approved performance data contained in the aeroplane flight manual is used to determine compliance with the requirements of the appropriate subpart, supplemented as necessary with other data acceptable to the Authority as prescribed in the relevant subpart. When applying the factors prescribed in the appropriate subpart, account may be taken of any operational factors already incorporated in the aeroplane flight manual performance data to avoid double application of factors. ...
OPS 1.515
Landing — dry runways
Landing — dry runways
(a) An operator shall ensure that the landing mass of the aeroplane determined in accordance with OPS 1.475(a) for the estimated time of landing at the destination aerodrome and at any alternate aerodrome allows a full stop landing from 50 ft above the threshold:
(1) for turbo-jet powered aeroplanes, within 60 % of the landing distance available; or
(2) for turbo-propeller powered aeroplanes, within 70 % of the landing distance available; ...
OPS 1.520
Landing — wet and contaminated runways
Landing — wet and contaminated runways
(a) An operator shall ensure that when the appropriate weather reports or forecasts, or a combination thereof, indicate that the runway at the estimated time of arrival may be wet, the landing distance available is at least 115 % of the required landing distance, determined in accordance with OPS 1.515. ...
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Thankyou FE Hoppy and CheckBoard for the refrences and the document's text. If I have understood correctly according to the document OPS 1.475 and 1.515, 40% safety margin is required for turbo jets. ( i.e. within 60 % of the landing distance available)
According to this document, this factor (i.e. 40% for turbo jets) also applies at the start of takeoff in addition to inflight re-planning. (If I have understood correctly).
So where does the 67% dispatch safety factor go according to these documents? Is 67% only a Boeing figure?
According to this document, this factor (i.e. 40% for turbo jets) also applies at the start of takeoff in addition to inflight re-planning. (If I have understood correctly).
So where does the 67% dispatch safety factor go according to these documents? Is 67% only a Boeing figure?