Definition
An instrument approach used in Simultaneous Offset Instrument Approach (SOIA) operations, in which one aircraft flies an LDA (Localizer-type Directional Aid) final approach course offset from the runway centerline while also receiving vertical guidance from a glideslope. The offset course allows it to be flown at the same time as an ILS or RNAV approach to a closely spaced parallel runway, with both aircraft monitored by Precision Runway Monitor (PRM) radar. After breaking out visually, the LDA/PRM pilot maneuvers to align with the runway for landing.
Plain English
It is a special approach used at airports with two runways close together. One aircraft flies a path that is angled slightly off from its runway, while another flies straight in to the parallel runway. Both get vertical guidance down, and high-precision radar watches them to keep them safely apart. Near the bottom, the pilot on the angled approach sees the runway and turns slightly to line up and land.
Context Anchor
Seen on instrument approach charts and in ATC clearances for airports using simultaneous offset instrument approaches to closely spaced parallel runways.
Derivation
LDA means Localizer-type Directional Aid -- a localizer signal that is not aligned with a runway, so it can only direct (guide) you, not bring you straight in. PRM means Precision Runway Monitor, a high-update radar used to precisely monitor parallel approaches. Together they describe an offset lateral guide plus a vertical glideslope, watched by precision radar.
Why Pilots Care
Enables higher arrival rates at busy airports by safely permitting simultaneous landings on parallel runways spaced less than 4,300 feet apart.
Grounding Statement
Picture flying down a guided, slightly angled path toward one runway while another aircraft flies a nearby parallel approach and controllers watch both aircraft closely.
Intuition Check
Do not assume “with glideslope” makes this the same as a straight-in ILS. The approach still uses an LDA course, which may be offset from the runway centerline.
Example Sentence 1
Cleared for the LDA/PRM approach with glideslope to runway 28L, the crew briefed the offset course, the visual segment, and the breakout procedure before beginning the descent.
Example Sentence 2
ATC cleared the flight for the LDA/PRM approach with glideslope while monitoring the parallel traffic on the PRM display.