B737 MCP - SPD Button
Join Date: Mar 2001
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Yup, minimum speed reversion is, as c100driver correctly posted, an elevator speed mode, therefore it is not available during autopilot modes where a defined flightpath is followed.
Minimum speed protection from autothrust in ARM is however still available after G/S capture. In the THY case it wouldn't have helped however, as RA 1 below 27ft would have commanded a RETARD anyway if the thrust levers were not in idle.
Minimum speed protection from autothrust in ARM is however still available after G/S capture. In the THY case it wouldn't have helped however, as RA 1 below 27ft would have commanded a RETARD anyway if the thrust levers were not in idle.
Join Date: Jun 2006
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Thanks Denti, so using A/T in ARM potentially could have saved a 737 in an Asiana SFO type incident (crew simply not watching airspeed on approach).
That was what I was getting at, despite the fact that this is not recommended by Boeing nor an approved SOP in many or most airlines.
That was what I was getting at, despite the fact that this is not recommended by Boeing nor an approved SOP in many or most airlines.
The B777 does not have an A/T arm mode similar to the B737.
Boeing does not recommend the arm mode due to the "mode confusion" argument and secondly an increase risk of tail strike.
I have read reports on two incidences of mode confusion caused by A/T arm and could certainly see how Boeing came to that 'all on or all off' conclusion. If fact our flight ops management changed from A/T arm to "all off" after those incidence.
The tail strike risk was demonstrated to me once and I was not that convinced about the likelihood but that was with the best of the breed. The B733.
The problem with FCOM is that Boeing produces a "tail generic" FCOM for the operator that is supposed to cover the tail specific serial number jets in an operators fleet. From this generic FCOM the operator then customises the FCOM for its own operation. That is why you get all the weird statements like "alpha floor" because some Chief Pilot thought it was better to call it that.
If your operator has its Airline name at the top of the FCOM then it is a customised version.
Boeing does not recommend the arm mode due to the "mode confusion" argument and secondly an increase risk of tail strike.
I have read reports on two incidences of mode confusion caused by A/T arm and could certainly see how Boeing came to that 'all on or all off' conclusion. If fact our flight ops management changed from A/T arm to "all off" after those incidence.
The tail strike risk was demonstrated to me once and I was not that convinced about the likelihood but that was with the best of the breed. The B733.
Interestingly it is called both alpha floor protection and minimum speed protection in my FCOM.
If your operator has its Airline name at the top of the FCOM then it is a customised version.
Last edited by c100driver; 14th Mar 2015 at 03:47. Reason: correction and additional information
Join Date: Oct 2006
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Cosmo,
I had an at or above crossing yesterday and needed full thrust to make it. We were at CLB-1. I had the CA delete CLB-1. You're saying that a second push of N1 will clear CLB-1 or -2?
I had an at or above crossing yesterday and needed full thrust to make it. We were at CLB-1. I had the CA delete CLB-1. You're saying that a second push of N1 will clear CLB-1 or -2?
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No I meant that after takeoff when throttles are in arm, a push on N1 will give your climb thrust. You still need to delete derated climb thrust in the FMC.
Again sorry for mixing it in here, as it doesn't have anything to do with the speed button..
Again sorry for mixing it in here, as it doesn't have anything to do with the speed button..
