Comment by tzs

A good example of the difference it can make was the Flight 191 crash in Chicago in in 1979, which had an engine come off on takeoff: https://en.wikipedia.org/wiki/American_Airlines_Flight_191

The engine coming completely off tore through hydraulic lines, which were need to keep the slats extended. Airflow forced the slats to retract.

Here's what then happened:

> As the aircraft had reached V1, the crew was committed to takeoff, so they followed standard procedures for an engine-out situation. This procedure is to climb at the takeoff safety airspeed (V2) and attitude (angle), as directed by the flight director. The partial electrical power failure, produced by the separation of the left engine, meant that neither the stall warning nor the slat retraction indicator was operative. Therefore, the crew did not know that the slats on the left wing were retracting. This retraction significantly raised the stall speed of the left wing. Thus, flying at the takeoff safety airspeed caused the left wing to stall while the right wing was still producing lift, so the aircraft banked sharply and uncontrollably to the left. Simulator recreations after the accident determined that "had the pilot maintained excess airspeed the accident may not have occurred.