ICAO has acknowledged that "communications, or the lack thereof, has been shown by many accident investigations to play a significant role".
[1] In 2003, the ICAO "released amendments to annexes of its Chicago Convention requiring aviation professionals involved in international operations to demonstrate a defined level of English language proficiency in the context of aeronautical communications".
Although the language proficiency of aviation professionals who are native speakers of English may typically be considered to be equivalent to Expert Level 6 on the ICAO Scale, they may also be sub-standard communicators in Aviation English, specifically by being prone to the use of non-standard terms, demonstrating impatience with non-native speakers, and speaking excessively, as well as too quickly.
While the ELPAC test for air traffic controllers (developed by Eurocontrol, in partnership with Zurich University of Applied Sciences/ZHAW) and ENOVATE[4]) is currently the only test formally recognized by ICAO as being fully compliant with ICAO Doc 9835,[5][6] the TEA, the TEAP, and the EALTS all have recognition from numerous National Aviation Authorities and licensing authorities, including the UK CAA, as being both ICAO Doc 9835 and EASA compliant.
Tests measure the applicants' language competencies across six holistic descriptors (Pronunciation, Structure, Vocabulary, Fluency, Comprehension, Interaction).