The double-slotted flap is similar to a single-slotted flap, except it has two slots; that is, the flap is divided into two segments, each with a slot as sketched in Figure 5.54-4. A flap with two slots almost doubles the advantages of a single-slotted flap. This benefit is achieved at the cost of increased mechanical complexity and higher cost. Most modern turboprop transport aircraft such as the ATR-42 (Figure 3.8) and several jet aircraft such as the jet trainer Kawasaki T-4 employ a double-slotted flap. The jet transport aircraft Boeing 767 (Figure 5.4) has a single-slotted outboard flap and a double-slotted inboard flap. It is common practice to deflect the first segment (slot) of the flap during a take-off operation, but employ full deflection (both segments) during landing. The reason is that more lift coefficient is needed during landing than at take-off.