Figure 1-68.  Spoilers deployed upon landing on a transport category  aircraft.  Figure 1-66.  Side view (left) and front view (right) of a Krueger flap on a Boeing 737.  Figure 1-67.  Air passing through the slot aft of the slat promotes  boundary layer airflow on the upper surface at high angles of attack.  The speed brake control in the cockpit can deploy all spoiler  and speed brake surfaces fully when operated. Often, these  surfaces are also rigged to deploy on the ground automatically  when engine thrust reversers are activated.  the spoilers remain stowed. As the speed of the aircraft  increases, the ailerons become more effective and the spoiler  interconnect disengages. Spoilers are unique in that they may also be fully deployed  on both wings to act as speed brakes. The reduced lift and  increased drag can quickly reduce the speed of the aircraft in  flight. Dedicated speed brake panels similar to flight spoilers  in construction can also be found on the upper surface of  the wings of heavy and high-performance aircraft. They are  designed specifically to increase drag and reduce the speed  of the aircraft when deployed. These speed brake panels  do not operate differentially with the ailerons at low speed. The force of the air against a control surface during the high  speed of flight can make it difficult to move and hold that  control surface in the deflected position. A control surface  might also be too sensitive for similar reasons. Several different  tabs are used to aid with these types of problems. The table  in  Figure 1-69  summarizes the various tabs and their uses.  1-31 Tabs 