Originally Posted by
Capn Bloggs
6° per second? You have got to be joking. The 717 (shortish DC-9) FCOM recommends 2.5° per second and that feels too fast.
The 6° per second rate of rotation can result in higher than desirable angle of attack as the airplane becomes airborne.
Understatement of the century.
This accident involved an ABEX DC-9 in PHL many yaers ago in freezing drizzle conditions without being de-iced. Aside from rapid roll reversals, their power dropped off significantly due to turbulent airflow into the nearby engine inlets(during certification MacDac had seen this stall/power loss combination when doing high altitude stalls which happen at a lower AoA). Similar happened to TWA and Ozark DC-9's in earlier incidents. Apparently longer body DC-9's are not vulnerable to this as the turbulent airflow goes above the tail.
It is interesting to note that for baby DC-9's, the slower rotation rate recommended by the NTSB and the procedural changes concerning rotation rate made by ABEX only applied to icing conditions.