Definition
The painted runway surface marking that defines the holding position for an Instrument Landing System (ILS) critical area. It consists of two yellow solid lines connected by a series of yellow rungs (short perpendicular bars), forming a ladder pattern across the taxiway. Aircraft and vehicles must hold short of this marking when ILS critical area protection is in effect, to prevent interference with the ILS signal being used by an arriving aircraft.
Plain English
It's a yellow ladder shape painted across a taxiway. When ILS protection is active, you stop before this line so your aircraft doesn't disturb the radio signals guiding a plane that is landing.
Context Anchor
Seen on taxiways near runways with an Instrument Landing System, often near an ILS holding position sign.
Derivation
Called a 'ladder' because the two parallel yellow lines joined by rungs look exactly like a ladder lying flat on the pavement. The shape is deliberately distinct from other hold lines so pilots recognize it instantly as the ILS critical area boundary.
Why Pilots Care
Crossing this marking without clearance can distort localizer and glideslope signals, causing false guidance to aircraft on approach.
Grounding Statement
Picture the marking as a painted stop line for keeping aircraft out of a protected signal area.
Intuition Check
Do not read “ladder” as equipment you climb. Here it means a flat painted pattern on the pavement that looks like ladder rungs.
Example Sentence 1
Tower instructed us to hold short of the ILS critical area, so I stopped just before the horizontal yellow ladder painted across the taxiway.
Example Sentence 2
During the pre-taxi briefing the captain pointed out the horizontal yellow ladder as our clearance limit for the ILS runway.