B737 Minimum Speed Reversion Mode

[lucalaz]

Quoting the 737 FCOM2-Chapter 4 with regard to the Minimum Speed Reversion Mode:

" Minimum speed reversion is not available when the A/T is OFF and the AFDS is in ALT HOLD or after G/S capture."

According to my interpretation of the above statement if A/T is ON then the Min Speed Reversion is available when in ALT HOLD or G/S capture but I have come across a different interpretation which says that Min Speed Reversion is NOT available when the A/T is OFF or G/S is captured or in ALT HOLD - i.e. even if A/T is ON Minimum Speed Reversion is NOT available when in ALT HOLD or G/S capture.

Anyone knows the correct logic used by Mr Boeing? :confused:

[cosmo kramer]

Minimum speed reversion is available in altitude hold and with G/S capture when the auto throttle is ON. In these cases the A/T can command a higher thrust setting, because it's ON. If it is off the aircraft will try to hold either level flight or glide slope at the expense of speed. The same goes for VNAV path when flying a level segment.

In other cases where the auto throttle is OFF, minimum speed reversion is still available since the autopilot is able to control the speed using pitch. If flying in vertical speed mode or VNAV (climb or descent) the autopilot will revert to Level Change.

[lucalaz]

That makes sense, just as I thought.

Thank you for your answer. :ok: