What did the safety pilot do? Why was nothing said about airspeed? safety pilot has really nothing else to do but monitor the other two.
I'm not familiar with the ergonomics of the 737NG cockpit as it relates to the jump seat. But the safety pilot may not have been in a position to make a useful contribution under the particular circumstances of the accident flight. To get any useful information from a speed tape you have to be able to read the numbers, which he may not have been able to do from his perch further back in the cockpit. A round dial gauge with a needle and speed bug would perhaps have afforded the safety pilot more of an opportunity to recognize and alert the crew to a slow speed situation.