Hook ladder

A hook ladder, also known as a pompier ladder (from the French pompier meaning firefighter) is a type of ladder that can be attached to a window sill or similar ledge by the use of a hooked extending bill with serrations on the underside.

The hooked ladder then hangs suspended vertically down the face of the building.

The original French design was a single beam ladder with pairs of rungs projected outward on both sides of the beam.

The British version was a conventional two-string ash ladder around 4 metres (13 ft) long and 25 centimetres (10 in) wide.

The ladders hook onto the window ledge by a "gooseneck" projecting from the top.