During CAT IIIA/IIIB approach where the decision height is 50 ft/0 ft, if the Runway Visual Range requirement for the approach is not met, what is a pilot to do?

I mean, 50 ft (or even 100 ft?) seem so low enough that a go around can not be initiated. Unless the pilot knows the RVR beforehand how can he be sure to perform CAT III approach?

  • $\begingroup$ They get the RVR via radio, they can get up to three different RVRs too, touchdown, mid-point and rollout. $\endgroup$
    – falstro
    Apr 22, 2016 at 10:21

1 Answer 1


Pilots get the RVR values either from weather reports or directly from ATC. RVR also shows up on ATIS reports when visibility drops to less than 1 mile. ATC will have a realtime readout of RVR and can communicate these values to pilots at any time by radio.

ATC RVR display

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Source: http://mtechsystems.com

The CAT III approach should only be commenced if the ceiling and RVR values meet the minimum for the approach in use and for the current aircraft equipment status. Some airlines will have their own minimums which can differ from the published CAT III minimums.

Pilots will often ask for the latest ceiling and RVR values while doing the approach. ATC will also announce any changes or reduction in ceiling or RVR values while aircraft are on approach. If the new values are below limits, the crew should commence a go-around.

A go-around can be done from any altitude and the wheels can touch the runway during the go-around. Low atlitude, "Low Energy" go-arounds are practiced during re-current Simulator training.

  • $\begingroup$ So if I understand it correct a go around can be initiated even when the main landing gear touches ground? $\endgroup$ Apr 22, 2016 at 13:13
  • 2
    $\begingroup$ Yes, most aircraft/airline procedures will say as long as reverse has not been selected, you may initiate a go-around. $\endgroup$ Apr 22, 2016 at 13:44
  • $\begingroup$ Is RVR usually on the ATIS? $\endgroup$
    – TomMcW
    Apr 22, 2016 at 17:26
  • $\begingroup$ When would ceiling be controlling for a Cat III approach? Vis, yes, but ceiling??? $\endgroup$
    – Ralph J
    Apr 22, 2016 at 19:08
  • $\begingroup$ Certain CAT III approaches require a decision height. It can vary according to aircraft type, equipment status, specific airline, or specific airport. $\endgroup$ Apr 22, 2016 at 21:14

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