Attn: 757, 767, 747 Crews - Erroneous Overspeed
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Attn: 757, 767, 747 Crews - Erroneous Overspeed
Hi all,
I was wondering if there is an overspeed CB in your cockpit to silence the Overspeed horn in the event of an erroneous overspeed?
And if so.. how often are you trained to pull such an overspeed CB if in fact located on a CB panel? During every recurrent?
I have spoken to CO, DL, AND UA crew... and none have been trained in such a procedure.
As far as they are aware, the only way to silence an overspeed, is to slow down the airplane.
Thoughts?
I was wondering if there is an overspeed CB in your cockpit to silence the Overspeed horn in the event of an erroneous overspeed?
And if so.. how often are you trained to pull such an overspeed CB if in fact located on a CB panel? During every recurrent?
I have spoken to CO, DL, AND UA crew... and none have been trained in such a procedure.
As far as they are aware, the only way to silence an overspeed, is to slow down the airplane.
Thoughts?
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In 14000 hours on the 757/767 I never heard of anyone even thinking of deactivating the over speed warning. Why would you want to? The only way to stop the warning was to SLOW the aircraft to below the MMO/VMO. The drill was simple close the thrust levers and pull speedbrake. Interestingly the limit on UK certified aircraft was lower than FAA certified ones, Mach .84 rather than Mach .86.
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Thank you for your reply Captain.
And forgive me for asking further, but have you ever been trained to pull an Overspeed CB in the event of an erroneous overspeed?
Further, if I may ask, do you know of an overspeed CB on your 757/767?
And forgive me for asking further, but have you ever been trained to pull an Overspeed CB in the event of an erroneous overspeed?
Further, if I may ask, do you know of an overspeed CB on your 757/767?
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I don't know why you were taught specifically about an overspeed C/B. In 15+ years I've never had an "erroneous" overspeed warning in any 747 model.
In our early 744 days, one airplane had repeated, random, erroneous aural warnings for several weeks. We eventually pulled an Aural Warning C/B (don't have a panel depiction to identify/locate it), but it silenced ALL aural warnings, including altitude alerts.
In our early 744 days, one airplane had repeated, random, erroneous aural warnings for several weeks. We eventually pulled an Aural Warning C/B (don't have a panel depiction to identify/locate it), but it silenced ALL aural warnings, including altitude alerts.
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Interestingly enough, the CRJ has such an option except it's not a CB, but rather two pushbuttons to the right of the F/O's right arm, one for each DCU. Pushing them would disable nearly ALL aural warnings, including the clacker.
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*Insert standard "not a pilot" disclaimer here*
The only examples I know of were a result of pitot-static problems rather than the warning system itself. I think that the general thing to do would be to work out why you're getting an erroneous overspeed warning - set pitch/power, see which side (if either) has correct airspeed information, flick the selector over to the side which is correct and finally decide whether to continue or land immediately.
The only examples I know of were a result of pitot-static problems rather than the warning system itself. I think that the general thing to do would be to work out why you're getting an erroneous overspeed warning - set pitch/power, see which side (if either) has correct airspeed information, flick the selector over to the side which is correct and finally decide whether to continue or land immediately.
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You're correct in what you say, Dozy. The main point of having the CB identified in a particular way (we had a coloured collar on it) was so that you could eliminate the distraction of the clacker going off when it was caused by something other than a genuine overspeed e.g. a blocked pitot during the climb. The noise is more than a tad annoying and doesn't allow for effective communication when trying to carry out the unreliable airspeed actions and hear what your mate is trying to tell you about pitch and power numbers from the QRH. Pulling the CB and getting rid of that awful noise genuinely gives you a LOT more capacity to get the job done.
Of course, the CB should not be pulled for a genuine overspeed but quietened by slowing the beast down.
Of course, the CB should not be pulled for a genuine overspeed but quietened by slowing the beast down.
Pontius has it right. Our fleet also has a coloured collar on the AURAL WARN SPKRS cb.
I did a high speed aborted take-off a couple of years ago when an Air Data Computer failure sent my ASI off scale and the Altimeter spinning skywards.
The noise associated with the overspeed warning was deafening, and you cant even begin to think until you have got rid of that noise.
The collars came about after the Birgenair crash.
I did a high speed aborted take-off a couple of years ago when an Air Data Computer failure sent my ASI off scale and the Altimeter spinning skywards.
The noise associated with the overspeed warning was deafening, and you cant even begin to think until you have got rid of that noise.
The collars came about after the Birgenair crash.
