It is very important that that air traffic control personnel and flight crews are proficient in speaking and understanding communications in the English language in a common standard.
Effective communication is an important process in everyday life. People must be able to communicate effectively with each other on both a personal as well as business level. Breakdowns in the communication processes can lead to misunderstandings, or worse, a major disaster.
Nowhere else is the communication process more important than in the cockpit of an aircraft. As history has repeatedly shown, a breakdown in the communication process often leads to less than desirable events that can be illustrated as follows:
· In 1977, at Tenerife in the Canary Islands, heavy accents and improper terminology among a Dutch KLM crew, an American Pan Am crew and a Spanish air traffic controller led to the worst aviation disaster in history, in which 583 passengers perished.
· In 1980, another Spanish air traffic controller at Tenerife gave a holding pattern clearance to a Dan Air flight by saying "turn to the left" when he should have said "turns to the left" - resulting in the aircraft making a single left turn rather than making circles using left turns. The jet hit a mountain killing 146 people.
· In 1990, Colombian Avianca pilots in a holding pattern over Kennedy Airport told controllers that their 707 was low on fuel. The crew should have stated they had a "fuel emergency," which would have given them immediate clearance to land. Instead, the crew declared a "minimum fuel" condition and the plane ran out of fuel, crashing and killing 72 people.
· In 1993, Chinese pilots flying a U.S.-made MD-80 were attempting to land in northwest China. The pilots were baffled by an audio alarm from the plane's ground proximity warning system. A cockpit recorder picked up the pilot's last words: "What does 'pull up' mean?"
· In 1995, an American Airlines jet crashed into a mountain in Colombia after the captain instructed the autopilot to steer towards the wrong beacon. A controller later stated that he suspected from the pilot's communications that the jet was in trouble, but that the controller's English was not sufficient for him to understand and articulate the problem.
· On November 13, 1996, a Saudi Arabian airliner and a Kazakhstan plane collided in mid-air near New Delhi, India. While an investigation is still pending, early indications are that the Kazak pilot may not have been sufficiently fluent in English and was consequently unable to understand an Indian controller giving instructions in English.
. In 2009 an Aircraft enroute from Amsterdam to Kuwait, while flying southbound on airway UP975 inbound fix ILMAP in Bagdad airspace, the flight was cleared by ATC "Callsign, descend to FL250 by ILMAP". The flightcrew started their descent shortly abefore ILMAP. A few miles past ILMAP, ATC informed the crew that they were descending through FL390 while they were supposed to be at FL250. The The flightcrew read back the received clearance "descent FL250 by ILMAP" and stated that they were at that moment descending to FL250. The ATC controller informed the crew taht the clearance meant that they should have crossed ILMAP at FL250. The crew questioned this interpretation while in the meantime descending to FL250 at a maximum rat of descent using full speedbrakes. There was no conflicting traffic and there was no effect on the flight. The reporter stated that, in hindsight, the crearance was not according to ICAO standard RT phraseology and was not clear, suggesting starting descent at ILMAP and that the ATC clearance should have been "Descent FL250 and cross ILMAP at FL250" or "descent FL250 to reach FL250 at ILMAP".
(Aviation Today: Special Reports and a Flightsafety magazine from a major European airline)