B737 Manual speed brake abort policy
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B737 Manual speed brake abort policy
Amazing how after all these years that 737's have been around some one just has to change a well tried and proven procedure.
Operator A uses pure Boeing which says that to carry out a rejected take off, use manual speed brake. Using reverse thrust lever which also brings up the speed brake is purely a back-up in case the pilot forget to pull manual speed brake.
Operator B doesn't agree with Boeing. They do not extend the speed brakes manually at all. They go for the reverse thrust levers and rely on them to actuate the speed brakes. Difference in time is very little unless there is a problem tugging into reverse.
Does this mean that Boeing and its test pilots have got it wrong all these years? Or is someone trying to reinvent the wheel?
Operator A uses pure Boeing which says that to carry out a rejected take off, use manual speed brake. Using reverse thrust lever which also brings up the speed brake is purely a back-up in case the pilot forget to pull manual speed brake.
Operator B doesn't agree with Boeing. They do not extend the speed brakes manually at all. They go for the reverse thrust levers and rely on them to actuate the speed brakes. Difference in time is very little unless there is a problem tugging into reverse.
Does this mean that Boeing and its test pilots have got it wrong all these years? Or is someone trying to reinvent the wheel?
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When I was in the B737-400 sim, the PNF, as stated in the before TO brief, Monitored the speed brake, the wheel brakes, alerted ATC and monitored the PF. That usually accounted for the case when the spoilers did not deploy automatically, the PNF just selected them.
Mr L
Mr L
Boeing may have considered the reliability of the automatic system or other failures associated with a need to abort that would result in not having an automatic system. Similarly, for those automatic systems that have to be armed, the manufacturer or operator may choose to consider any crew error in failing to set the system.
Then of course, there is the possible error in monitoring.
If in doubt ask the manufacturer for a detailed explanation; there may have been a change in the system design for new variant aircraft, or even Boeing may have made a mistake.
Then of course, there is the possible error in monitoring.
If in doubt ask the manufacturer for a detailed explanation; there may have been a change in the system design for new variant aircraft, or even Boeing may have made a mistake.
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Lots of pilots and airlines often discuss this. It is a very interesting question.
The thrustlever idle-to-reverse time delay is most effectively used to manually deploy speedbrakes which also will serve as a back up for auto-speedbrake failures,
Possible malfunctions with auto-speedbrake or reveres have happened so many times that it is even factored in during certification. Keep in mind that during JAR or FAR certification the reveres are not used to determine stopping distance, they just use thrust levers idle and speedbrakes manually deployed.
Late speedbrakes will affect the stopping distance. Next time you are in the sim, try to slam the forward thrustlevers to idle and note how there is a slight delay before you can move the reverse thrustlevers. This will dealy auto-speedbrakes. The most time efficient technique is actually: (1) Thrust lever idle, (2) manual speedbrakes, (3) reveres.
The thrustlever idle-to-reverse time delay is most effectively used to manually deploy speedbrakes which also will serve as a back up for auto-speedbrake failures,
Possible malfunctions with auto-speedbrake or reveres have happened so many times that it is even factored in during certification. Keep in mind that during JAR or FAR certification the reveres are not used to determine stopping distance, they just use thrust levers idle and speedbrakes manually deployed.
Late speedbrakes will affect the stopping distance. Next time you are in the sim, try to slam the forward thrustlevers to idle and note how there is a slight delay before you can move the reverse thrustlevers. This will dealy auto-speedbrakes. The most time efficient technique is actually: (1) Thrust lever idle, (2) manual speedbrakes, (3) reveres.
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Have to agree with Hudson and 80/20. It's amazing how many operators, especially new to type, want to mess about with tried and tested Boeing operating techniques.
The other good reason for the "thrust, speedbrake, reverse" order of doing things is that in the unlikely (but still allowable) event of dispatch with two inop reversers, crews will not be trying to move two wirelocked reverse thrust levers when they should be deployng the speedbrake.
The other good reason for the "thrust, speedbrake, reverse" order of doing things is that in the unlikely (but still allowable) event of dispatch with two inop reversers, crews will not be trying to move two wirelocked reverse thrust levers when they should be deployng the speedbrake.
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Actually that raises an interesting question. If you use the reverse thrust levers to actuate the speed brakes during an abort, does the speed brake lever snap back on the first movement of the reverse lever before the interlocks are released (and reverse is available) - or is it only after you get past the interlock gates.
Just to run that question again - will (say) a tiny itsy bitsy movement of the reverse levers en route to the interlocks position cause the speed brake lever to up?
Which leads on to the next part. Boeing recommend that when landing, the PNF call "Speed brakes up" or "Speed brakes not up" as appropriate.
If the captain is PF and failed to notice the speed brake lever was still down, he would presumably react on hearing the call "speed brakes not up" and pull the speed brake lever up. But would it not be quicker for the PNF to reach across and select the speed brake lever up - rather than make the "speed brake not up" bleat and hope that the captain would do something about it? At 200 feet per second of landing run, every second counts to get the weight on the wheels.
A case happened where the first officer called three times that the speed brake was not up, and after no reaction from the captain , the first officer leant across and pulled the speed brake up. This was just what the doctor ordered.
Only problem was the captain went right up him for carrying out an item out of his area of responsibility - even though it was the idiot captain that had stuffed up. There are some weirdos in the LH seat sometimes.
Just to run that question again - will (say) a tiny itsy bitsy movement of the reverse levers en route to the interlocks position cause the speed brake lever to up?
Which leads on to the next part. Boeing recommend that when landing, the PNF call "Speed brakes up" or "Speed brakes not up" as appropriate.
If the captain is PF and failed to notice the speed brake lever was still down, he would presumably react on hearing the call "speed brakes not up" and pull the speed brake lever up. But would it not be quicker for the PNF to reach across and select the speed brake lever up - rather than make the "speed brake not up" bleat and hope that the captain would do something about it? At 200 feet per second of landing run, every second counts to get the weight on the wheels.
A case happened where the first officer called three times that the speed brake was not up, and after no reaction from the captain , the first officer leant across and pulled the speed brake up. This was just what the doctor ordered.
Only problem was the captain went right up him for carrying out an item out of his area of responsibility - even though it was the idiot captain that had stuffed up. There are some weirdos in the LH seat sometimes.
Hudson, re moving the thrust levers near reverse in flight; I hope that the system design has at least two other interlocks in it, i.e weight on ground or wheel spin up in addition to the thrust levers, thus several failures would be required before the ground spoilers could deploy.
Re the calls to be made with deployment (or not) of the airbrake / ground spoilers.
There could be several human factor problems here. First, if a 'deployed' call is always made it become routine and may be given in error when the system / crew has failed; NB BAe146 landing overrun at Aberdeen. Then there could be problems for crew who change aircraft types, they may revert to previous habits.
In general, calls should be negative; this gives greater impact for the failure case.
The issue of calls was reviewed in the NTSB investigation into the AA MD82 accident in Little Rock. One recommendation was made as below, but this may have introduced as many problems as it cures; increased workload, opportunity for error, etc:
Re the calls to be made with deployment (or not) of the airbrake / ground spoilers.
There could be several human factor problems here. First, if a 'deployed' call is always made it become routine and may be given in error when the system / crew has failed; NB BAe146 landing overrun at Aberdeen. Then there could be problems for crew who change aircraft types, they may revert to previous habits.
In general, calls should be negative; this gives greater impact for the failure case.
The issue of calls was reviewed in the NTSB investigation into the AA MD82 accident in Little Rock. One recommendation was made as below, but this may have introduced as many problems as it cures; increased workload, opportunity for error, etc:
For all 14 Code of Federal Regulations Part 121 and 135 operators, require a callout if the spoilers do not automatically or manually deploy during landing and a callout when the spoilers have deployed, and verify that these operators include these procedures in their flight manuals, checklists, and training programs. The procedures should clearly identify which pilot is responsible for making these callouts and which pilot is responsible for deploying the spoilers if they do not automatically or manually deploy.
