SPOTLIGHT - Lower Airspace Radar Service (LARS)

[Darren Hill]

What is a LARS?

A Lower Airspace Radar Service (LARS) is a free service available to all aircraft for the provision of the radar element of UK Flight Information Services (UK FIS). This service is usually offered in a 30nm radius around the station at any aircraft below FL100 and outside of controlled airspace (Class A, C, D, E) within the limits of the radar equipment. The service can be offered to either VFR or IFR traffic.

Why get a service from a LARS unit?

Some of the main reasons for establishing LARS stations are to help prevent, and expeditiously rectify, controlled airspace infringements and to give aircraft one of the three Flight Information Services available in the UK. As such, it is not required to contact a LARS station when outside of controlled airspace.

More about UKFIS can be found in this post and a quick guide to airspace can be found here.

How do I know if I’m in an area with LARS coverage?

A map of the LARS unit coverage across the UK can be found on the AIP or from the Air and Safety Initiative. For VATSIM purposes, controllers manning a unit that has LARS will generally put whether they are covering the LARS region in their controller notes. If nothing is stated in the notes, the pilot may send the controller a private message or check in on frequency to enquire about whether a LARS service can be provided.

If an aircraft is not in an area of LARS coverage or the LARS station is offline, the pilot may get a service from a non-LARS unit. However, there is a much greater chance of a service higher than a basic service being denied due to other duties the controller must perform.

How do I call a LARS unit for a service?

An aircraft requesting a service from a LARS station should use the same radiotelephony as with any other radar unit. The pilot should first call up with their callsign and request only, which is then followed by CARPAR (an acronym to help remember all the information you must pass).

CARPAR

1. Callsign
2. Aircraft Type
3. Routing
4. Position
5. Altitude
6. Request

This is an example of the radiotelephony, where GPTDA is calling Farnborough for a traffic service.

Green – Aircraft (GPTDA)
Blue – Farnborough Radar

Farnborough Radar, GPTDA requesting traffic service.
GPTDA, Farnborough Radar, squawk 0435, pass your message.
GPTDA, Cessna 172, routing Goodwood to Biggin Hill, overhead Midhurst, altitude 1600ft on QNH 1015, request traffic service.
GDA, squawk 0435.
Squawk 0435, GDA.
GDA, identified, traffic service taking your own terrain clearance, London QNH 1015.
Traffic service, QNH 1015, GDA.

When the pilot is ready to change to the next frequency, they should report changing frequencies. The LARS station may coordinate a radar handover to the next station, in which case the service is seamlessly carried over to the next controller. If such a handover is not available, then the LARS controller will inform the pilot of the termination of the service and to squawk conspicuity (this may be 7000 for VFR/2000 for IFR or a local conspicuity, such as 7366 for the Manchester Listening code).

Edited April 5, 2021 by Darren Hill