Flight Crew Air Transport Pilot (ATP)
Situational Awareness; Human-Machine Interface
ATC Issue All Types; Deviation - Speed All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Became Reoriented; Flight Crew Took Evasive Action
Human Factors; Procedure
ATC gave us conflicting clearances for the arrival (3 times); so we were high coming into the approach phase. I had the speed brake deployed and had pulled the throttles back to try to come down to glideslope. The aircraft started to level off while we were high and I went to VS (Vertical Speed) and put in 1;800 feet rate of descent; the aircraft came out of VS and started to level again causing the aircraft to slow. The FO called we [are] in the hook (minimum maneuver speed) and I started to add power; we had a stick shaker for about 1 second. We caught the error and corrected it. We made a stable approach and landed without any further problems. Too many changes too close to the airport. I think the system worked as we caught our error and corrected it in a timely manner.
During the arrival into San Jose; Costa Rica; ATC gave us conflicting clearances for the arrival (3 times); which caused us to be high on PATH. The last altitude assigned was 9;000 feet (I think). The PF deployed the speed brakes in an effort to regain the PATH. The last clearance given was to proceed to ALTOS and descend via the PARRITA 4 arrival. I reprogrammed the FMS for the current clearance. The PF noticed that we were still high on path and reverted the vertical mode to VS (Vertical Speed); selecting -1800 FPM... the aircraft began to transition to a -1800 rate of descent; however we began to slow below our current flap maneuver speed. (I believe we were flaps 1 and there was a speed restriction at TOMAS of 160). The MCP altitude was not set to a lower altitude and the aircraft began to level and slow. I announced that we were in the hook (minimum maneuver speed). The PF began to add power; however stick shaker activated briefly. The PF noticed that the VS window closed (because we captured the MCP altitude). I stated that we did not have the lower altitude set. The PF set the lower altitude in the MCP and selected Flight Level Change (I think). A good correction was made to return above maneuver speed for the current flap setting. The remainder of the arrival an approach was stable and without incident. Due to the language challenges in Costa Rica and the conflicting ATC clearances; there was a breakdown in CRM. While attempting to program the FMS for the current clearance; I (PM) did not verify the correct lower altitude was set in the MCP. Additionally; the PF did not set a lower altitude in the MCP; reverted to VS to try to regain PATH; did not recognize the speed reduction; and did not quickly recognize that the plane was leveling at the current MCP altitude. As a crew; we could have been better at implementing the FOM automation philosophy. Once we noticed that we deviated from our flap maneuver speed; less time should have been spent trying to correctly automate.
B757 flight crew experiences multiple arrival changes during arrival to MROC resulting in the crew getting behind and the aircraft attempting to level and slow prematurely. Stick shaker is encountered and quickly corrected. The approach continues to landing.