Introduction

This article is intended to provide information on the use of time-critical phraseology based on ICAO Doc. 9432 Manual on Radiotelephony and on the UK Manual of Radiotelephony CAP 413. It also examines controllers’ and flight crews’ expectations regarding the use of “now”, “immediately” and “expedite” in ATC clearances, and identifies associated safety issues. The advice provided in this article shall not take precedence over applicable rules and local procedures.

Reasons for use

Controllers are trained to plan the situation well in advance to achieve smooth flow of air traffic. This sometimes means that the clearances have to be complied with without delay. There are also situations where things do not happen as intended, and prompt action becomes necessary. Examples of such situations are: