Idle reverse policy on landing
I C; and the definition of TDZ is …
ICAO definition.
Runway marking definition.
Performance definition, Boeing definition, or
the practical and required definition to provide adequate safety margin during landing.
ICAO definition.
Runway marking definition.
Performance definition, Boeing definition, or
the practical and required definition to provide adequate safety margin during landing.
BOAC, you might settle on a simple rule of thumb – type dependant, but it wouldn’t work everywhere; try the first third at LCY !! (Don’t). The important aspects are in the details, 'a and r'.
Another disadvantage is that if rules of thumb (RofT) are used as a ‘sop’, then this can reduce the perceived need for knowledge of landing performance and its dependencies, variables, etc, and reduce the crew's ability to calculate the actual landing distance required, i.e. not understanding the circumstances when the RofT must be ditched.
Conversely, with exemplary knowledge, and due consideration of the variables, the landing distance calculated can be checked with a RofT.
Pilots need to be encouraged to think about the problems and then check afterwards, a similar idea in some posts above about the use of reverse; if you are going to select it, then use it all.
Another disadvantage is that if rules of thumb (RofT) are used as a ‘sop’, then this can reduce the perceived need for knowledge of landing performance and its dependencies, variables, etc, and reduce the crew's ability to calculate the actual landing distance required, i.e. not understanding the circumstances when the RofT must be ditched.
Conversely, with exemplary knowledge, and due consideration of the variables, the landing distance calculated can be checked with a RofT.
Pilots need to be encouraged to think about the problems and then check afterwards, a similar idea in some posts above about the use of reverse; if you are going to select it, then use it all.
if you are going to select it, then use it all.
It's interesting that neither you nor anyone else will answer my query- if you think it necessary to use full reverse on every landing, why not also full brakes?
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@ safetypee.
Then how do you comply with Notes
"1.2.3 REVERSE THRUST
More than idle reverse shall not be used except for safety reasons or if necessitated to comply with ATC reuest" at LSGG, or
"1.2.2. REVERSE THRUST
Avoid use of reverse thrust after landing between 2330-0600LT except for safety reasons" at EGKK etc. etc.
Is that the real reason for the safety pee?
if you are going to select it, then use it all.
"1.2.3 REVERSE THRUST
More than idle reverse shall not be used except for safety reasons or if necessitated to comply with ATC reuest" at LSGG, or
"1.2.2. REVERSE THRUST
Avoid use of reverse thrust after landing between 2330-0600LT except for safety reasons" at EGKK etc. etc.
Is that the real reason for the safety pee?
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First 1/3... 330 or 340 (3,5,6) no problem............
If you can't stop with idle reverse and min autobrake you're a puss!!!!!!!!!!!!!!!!!!
Trust me
says 7,000 hrs on type
If you can't stop with idle reverse and min autobrake you're a puss!!!!!!!!!!!!!!!!!!
Trust me
says 7,000 hrs on type
Per Ardua ad Astraeus
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Originally Posted by wiz
if you think it necessary to use full reverse on every landing, why not also full brakes?
On reflection, #24 was glib - conceptual rather than absolute. There are few if any absolutes in aviation.
The concept of ‘use it all’ is similar to the mindstates of ‘how can we land’ vs ‘should we be landing’ in a pre-landing assessment. The objective (the latter) is to encourage crews to be aware of the assumptions in landing performance and thus the limitations of their landing decision.
Many overrun accidents involve misjudgments of the conditions or a poor choice of action. If these occur in combination with large, but normal variations of operating performance – unstable approach, high over threshold, landing fast, long, delayed deployment of spoilers, etc, then the risks of an overrun increase rapidly.
It should be possible to identify these risks and mitigate them before landing by deciding to change the planned level of braking and/or use of full reverse – a strategic decision. Any later identification of the need to change plan involves a ‘tactical’ assessment and is often complicated by time/workload pressures. This assessment often occurs when well down the runway, and approaching or exceeding the point of being able to prevent an overrun.
Certificated landing distances are based on the use of max braking with an added distance safety margin (factor). This margin “accounts for the normal operational variability that can be expected in day to day service such that the chances of a landing overrun are remote” ( Landing Performance Large Transport Aeroplanes ).
Thus if landings were routinely made at the limit of pilots’ variability, and on limiting runway lengths, max braking would be required to minimize the risk of an overrun to a chance less than ‘remote’.
Fortunately most pilots constrain their variability, and in general do not routinely land on limiting runways (ex LCY etc). However, this apparent normality in operation can lead to complacency.
Using the concept of max braking can minimise any additional risk from complacency, unexpected variability, misjudgement, misassessment, or poor plan of action. When a landing decision chooses not to use max braking, crews should have an improved awareness of the associated risks and mitigations for that landing, i.e. the crew thought about them before changing the ‘sop’ (max braking standard operating plan) to an acceptable alternative.
Brake for safety not for comfort.
Reverse is not normally considered in certificated landing performance due to reliability / consistency problems (CS/FAR 25.125).
If crews assume that the safety of a landing could be maintained by ‘late’ use of max reverse, based on their assessment of the situation, then there is some (significant) risk that reverse might not be available/used when required – and at a time/position on the runway where it would be effective.
Here, the concept of planning to use max reverse (‘sop’) can reduce these risks by checking that the ‘emergency late use’ of reverse will be available – that the system has deployed and the engine has spooled up immediately after touchdown. If reverse does not work, then braking can be increased much earlier to minimise the risk in the event of other problems – as above.
Use of reverse vs environmental impact should be considered as a separate, but important safety issue of conflicting goals and objectives. See refs to ETTO - efficiency / thoroughness tradeoff.
The frustrating point is that local authorities duck their responsibility for safety by placing the decision on operators and pilots.
The concept of ‘use it all’ is similar to the mindstates of ‘how can we land’ vs ‘should we be landing’ in a pre-landing assessment. The objective (the latter) is to encourage crews to be aware of the assumptions in landing performance and thus the limitations of their landing decision.
Many overrun accidents involve misjudgments of the conditions or a poor choice of action. If these occur in combination with large, but normal variations of operating performance – unstable approach, high over threshold, landing fast, long, delayed deployment of spoilers, etc, then the risks of an overrun increase rapidly.
It should be possible to identify these risks and mitigate them before landing by deciding to change the planned level of braking and/or use of full reverse – a strategic decision. Any later identification of the need to change plan involves a ‘tactical’ assessment and is often complicated by time/workload pressures. This assessment often occurs when well down the runway, and approaching or exceeding the point of being able to prevent an overrun.
Certificated landing distances are based on the use of max braking with an added distance safety margin (factor). This margin “accounts for the normal operational variability that can be expected in day to day service such that the chances of a landing overrun are remote” ( Landing Performance Large Transport Aeroplanes ).
Thus if landings were routinely made at the limit of pilots’ variability, and on limiting runway lengths, max braking would be required to minimize the risk of an overrun to a chance less than ‘remote’.
Fortunately most pilots constrain their variability, and in general do not routinely land on limiting runways (ex LCY etc). However, this apparent normality in operation can lead to complacency.
Using the concept of max braking can minimise any additional risk from complacency, unexpected variability, misjudgement, misassessment, or poor plan of action. When a landing decision chooses not to use max braking, crews should have an improved awareness of the associated risks and mitigations for that landing, i.e. the crew thought about them before changing the ‘sop’ (max braking standard operating plan) to an acceptable alternative.
Brake for safety not for comfort.
Reverse is not normally considered in certificated landing performance due to reliability / consistency problems (CS/FAR 25.125).
If crews assume that the safety of a landing could be maintained by ‘late’ use of max reverse, based on their assessment of the situation, then there is some (significant) risk that reverse might not be available/used when required – and at a time/position on the runway where it would be effective.
Here, the concept of planning to use max reverse (‘sop’) can reduce these risks by checking that the ‘emergency late use’ of reverse will be available – that the system has deployed and the engine has spooled up immediately after touchdown. If reverse does not work, then braking can be increased much earlier to minimise the risk in the event of other problems – as above.
Use of reverse vs environmental impact should be considered as a separate, but important safety issue of conflicting goals and objectives. See refs to ETTO - efficiency / thoroughness tradeoff.
The frustrating point is that local authorities duck their responsibility for safety by placing the decision on operators and pilots.
Last edited by safetypee; 24th May 2012 at 13:49.
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It's interesting that neither you nor anyone else will answer my query- if you think it necessary to use full reverse on every landing, why not also full brakes?
Sheppey, re “Max brakes on most landings at max landing weight will cause …”
You present a fairly definitive position, which for many aircraft types is incorrect.
What about the much higher energies in a MTOW RTO; then the conditions you quote might be encountered. Even with hot brakes etc, the certification regulations require that there is no significant hazard; e,g, a brake fire in tests should be allowed to exist for 5 min before extinguishing.
Many people make erroneous interpretations from sensational graphic images, which if recalled from memory during operations can adversely bias situation assessments and subsequent actions.
High decelerations may be encountered when landing on a dry surface with max brake, but with anti-skid in wet conditions the deceleration would be most acceptable – as well as very necessary to stop safely.
Use max reverse, but don’t discard max brakes when required, particularly at lower speeds.
You present a fairly definitive position, which for many aircraft types is incorrect.
What about the much higher energies in a MTOW RTO; then the conditions you quote might be encountered. Even with hot brakes etc, the certification regulations require that there is no significant hazard; e,g, a brake fire in tests should be allowed to exist for 5 min before extinguishing.
Many people make erroneous interpretations from sensational graphic images, which if recalled from memory during operations can adversely bias situation assessments and subsequent actions.
High decelerations may be encountered when landing on a dry surface with max brake, but with anti-skid in wet conditions the deceleration would be most acceptable – as well as very necessary to stop safely.
Use max reverse, but don’t discard max brakes when required, particularly at lower speeds.
Last edited by alf5071h; 25th May 2012 at 01:28.
