Skip to content

1.6 Radar Limitations

1.6.1 General

Radar surveillance systems are subject to technical and operational limitations.

The Approach Controller shall understand these limitations and adjust control techniques accordingly.

Radar information shall not be used where its accuracy or reliability is in doubt.

1.6.2 Types of Limitations

The Approach Controller shall be aware of the following limitations:

(a) Coverage Limitations

  • Areas of reduced or no radar coverage
  • Low-level coverage gaps
  • Terrain shielding effects

(b) Accuracy and Update Limitations

  • Delay between radar updates
  • Inaccuracy in position reporting
  • Target smoothing or lag

(c) Altitude Information (Mode C)

  • Incorrect or unreliable altitude readouts
  • Unverified Mode C
  • Transponder malfunction

(d) Transponder and SSR Limitations

  • Transponder failure or incorrect squawk
  • Loss of Mode A, C, or S data
  • Multiple aircraft using incorrect codes

(e) Communication Limitations

  • Poor radio reception
  • Frequency congestion
  • Delayed or missed pilot responses

1.6.3 Operational Impact

When radar limitations are identified, the Approach Controller shall:

  • Increase separation between aircraft
  • Reduce traffic complexity
  • Apply conservative control techniques
  • Monitor aircraft more closely

Where necessary, the controller shall revert to procedural control methods.

1.6.4 Use of Radar for Separation

The Approach Controller shall not use radar for separation when:

  • Aircraft are not positively identified
  • Surveillance data is unreliable
  • Mode C altitude is not verified
  • Radar coverage is inadequate

Alternative separation methods shall be applied in such cases.

1.6.5 Degraded Surveillance Operations

In degraded radar conditions, the Approach Controller shall:

  • Limit the number of aircraft under control
  • Increase spacing between aircraft
  • Avoid complex instructions
  • Coordinate with adjacent units as required

Traffic shall not be accepted beyond the controller’s capacity to maintain safe separation.

1.6.6 Key Principle

Radar is a tool to support control, not a guarantee of accuracy.

The Approach Controller shall:

  • Verify surveillance information
  • Recognise limitations
  • Adapt control techniques accordingly

Safety shall be maintained even when surveillance capability is reduced.